diff --git "a/raw_rss_feeds/https___arxiv_org_rss_astro_ph.xml" "b/raw_rss_feeds/https___arxiv_org_rss_astro_ph.xml" --- "a/raw_rss_feeds/https___arxiv_org_rss_astro_ph.xml" +++ "b/raw_rss_feeds/https___arxiv_org_rss_astro_ph.xml" @@ -7,2104 +7,2502 @@ http://www.rssboard.org/rss-specification en-us - Fri, 12 Dec 2025 05:00:06 +0000 + Fri, 19 Dec 2025 05:00:15 +0000 rss-help@arxiv.org - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 Saturday Sunday - Decisively Demonstrating Roman CGI's TTR5 Requirement by Reimaging a Newly-Discovered Brown Dwarf Orbiting a Bright Accelerating Star - https://arxiv.org/abs/2512.09977 - arXiv:2512.09977v1 Announce Type: new -Abstract: We propose Roman Coronagraph project HLC/575 nm observations of a newly-discovered brown dwarf (HIP 71618 B) from the Subaru/OASIS survey of young accelerating stars, which is supported by NASA headquarters with the directive to identify targets for the Roman Coronagraph that could fulfill TTR5 requirements and be observed during the technology demonstration phase. The target and multiple bright PSF references are within/close to the Roman Continuous Viewing Zone. A high SNR detection of this companion would singlehandedly fulfill TTR5 and would be the first optical detection of a companion at $<$10$^{-6}$ contrast. - Roman CPP reference star vetting prioritizing stars that can be paired with HIP 71618 would aid the execution of a successful technology demonstration. Additional similar targets may be discovered from OASIS over the next few years that could increase CGI scheduling flexibility and enhance its scientific and technical return. A close collaborative partnership with the CPP team could ensure that they are schedulable. - oai:arXiv.org:2512.09977v1 + Reconstruction of the dark matter density profile from cosmic positron anomaly data + https://arxiv.org/abs/2512.15741 + arXiv:2512.15741v1 Announce Type: new +Abstract: In this work we continue our investigations of the possibility of explanation of the positron anomaly (PA) in cosmic rays with the help of annihilating or decaying dark matter (DM) component by varying its space distribution. In the contrast of our previous studies, where we first assumed some specific spatial distribution of DM component and looked at how it agrees with data, here we solve, in some sense, the inverse problem: we search for distribution, in a mathematical way, which satisfies observational data. A unique algorithm has been implemented which, using linear algebra and adaptive grid methods, adjusts distribution to the data. It allows telling in principle whether or not is possible to solve PA problem by variation of spatial distribution of DM sources. A positive result has been formally obtained. A class of solutions can be identified. Though the distributions obtained at the chosen injection spectra may seem slightly realistic, nonetheless it demonstrates a quite powerful possibility in explaining PA that could be realized in more realistic models. + oai:arXiv.org:2512.15741v1 + astro-ph.HE + astro-ph.CO + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + K. M. Belotsky, F. V. Kostromin, M. L. Solovyov + + + An Improved Machine Learning Approach for RFI Mitigation in FAST-SETI Survey Archival Data + https://arxiv.org/abs/2512.15809 + arXiv:2512.15809v1 Announce Type: new +Abstract: The search for extraterrestrial intelligence (SETI) commensal surveys aim to scan the sky to detect technosignatures from extraterrestrial life. A major challenge in SETI is the effective mitigation of radio frequency interference (RFI), a critical step that is particularly vital for the highly sensitive Five-hundred-meter Aperture Spherical radio Telescope (FAST). While initial RFI mitigation (e.g., removal of persistent and drifting narrowband RFI) are essential, residual RFI often persists, posing significant challenges due to its complex and various nature. In this paper, we propose and apply an improved machine learning approach, the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm, to identify and mitigate residual RFI in FAST-SETI commensal survey archival data from July 2019. After initial RFI mitigation, we successfully identify and remove 36977 residual RFIs (accounting for $\sim$ 77.87\%) within approximately 1.678 seconds using the DBSCAN algorithm. This result shows that we have achieved a 7.44\% higher removal rate than previous machine learning methods, along with a 24.85\% reduction in execution time. We finally find interesting candidate signals consistent with previous studies, and retain one candidate signal following further analysis. Therefore, DBSCAN algorithm can mitigate more residual RFI with higher computational efficiency while preserving the candidate signals that we are interested in. + oai:arXiv.org:2512.15809v1 astro-ph.IM - astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Thayne Currie, Brianna Lacy, Mona El Morsy, Masayuki Kuzuhara, Naoshi Murakami, Danielle Bovie + Li-Li Zhao, Xiao-Hang Luan, Xin Chao, Yu-Chen Wang, Jian-Kang Li, Zhen-Zhao Tao, Tong-Jie Zhang, Hong-Feng Wang, Dan Werthimer - UV Luminosity Functions from HST and JWST: A Possible Resolution to the High-Redshift Galaxy Abundance Puzzle and Implications for Cosmic Strings - https://arxiv.org/abs/2512.09980 - arXiv:2512.09980v1 Announce Type: new -Abstract: Recent observations of high redshift galaxies by the James Webb Space Telescope suggest the presence of a bright population of galaxies that is more abundant than predicted by most galaxy formation models. These observations have led to a rethinking of these models, and numerous astrophysical and cosmological solutions have been proposed, including cosmic strings, topological defects that may be remnants of a specific phase transition in the very early moments of the Universe. In this paper, we integrate cosmic strings, a source of nonlinear and non-Gaussian perturbations, into the semi analytical code Zeus21, allowing us to efficiently predict the ultraviolet luminosity function (UVLF). We conduct a precise study of parameter degeneracies between star-formation astrophysics and cosmic-string phenomenology. Our results suggest that cosmic strings can boost the early-galaxy abundance enough to explain the measured UVLFs from the James Webb and Hubble Space Telescopes from redshift z = 4 to z = 17 without modifying the star-formation physics. In addition, we set a new upper bound on the string tension of $G\mu \lessapprox 10^{-8}$ ($95\%$ credibility), improving upon previous limits from the cosmic microwave background. Although with current data there is some level of model and prior dependence to this limit, it suggests that UVLFs are a promising avenue for future observational constraints on cosmic-string physics. - oai:arXiv.org:2512.09980v1 - astro-ph.CO + Milky Way disc & Bulge in situ populations: ESO white paper - Expanding horizons call + https://arxiv.org/abs/2512.15812 + arXiv:2512.15812v1 Announce Type: new +Abstract: The formation and evolution of the Milky Way's disc, bar, and bulge remain fundamentally limited by the lack of a contiguous, Galaxy-wide, high-precision chemo-dynamical map. Key open questions - including the survival or destruction of the primitive discs, the origin of the bulge's multi-component structure, the role of mergers and secular processes, and the coupling between stellar chemistry, dynamics, and the Galactic potential - cannot be fully resolved with current or planned facilities. Existing spectroscopic surveys provide either high resolution for small samples or wide coverage at insufficient resolution and depth, and none can obtain homogeneous abundances, precise 3D kinematics, and reliable ages for the millions of stars required, particularly in the obscured midplane, the far side of the bar, or the outer, low-density disc. A new wide-field, massively multiplexed, large-aperture spectroscopic facility, capable of both high- and low-resolution spectroscopy over tens of thousands of square degrees, is therefore essential. Such a facility would deliver the statistical power, sensitivity, and completeness needed to reconstruct the Galaxy's assembly history, constrain its gravitational potential, and establish the Milky Way as the definitive benchmark for galaxy evolution. + oai:arXiv.org:2512.15812v1 + astro-ph.IM astro-ph.GA - gr-qc - hep-ph - hep-th - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + M. Bergemann, G. Kordopatis, G. Casali, S. Khoperskov, P. McMillan, L. Marques, I. Minchev, E. Poggio, M. Schultheis, C. Viscasillas V\'azquez, H. -F. Wang, V. Grisoni, V. Hill, R. Smiljanic + + + Asteroseismology of white dwarfs in the 2040s + https://arxiv.org/abs/2512.15814 + arXiv:2512.15814v1 Announce Type: new +Abstract: White dwarfs, the final evolutionary stage of the vast majority of stars, serve as critical tools for cosmochronology, studies of planetary system evolution, and laboratories for non-standard physics, including exotic cooling channels and weakly interacting particles, as well as crystallization processes. Beyond surface properties accessible via spectroscopy and model atmospheres, global pulsations exhibited by white dwarfs during various evolutionary phases provide a direct window into their deep interiors. Asteroseismology, the comparison of observed pulsation periods with theoretical models, enables us to infer internal chemical stratification, total mass, rotation profiles, and magnetic field strengths. Despite major advances from space missions providing uninterrupted, high-precision photometry, key challenges remain: many predicted pulsators remain quiet, while others oscillate outside theoretical instability strips, highlighting gaps in our understanding of mode excitation, diffusion, and convective mixing. Determining the masses of white dwarfs, particularly for massive and hydrogen-deficient stars, remains uncertain, with discrepancies between spectroscopic, asteroseismic, astrometric, and photometric methods. In the coming decades, large-scale surveys combining high-precision space-based photometry with coordinated ground-based spectroscopic follow-up will dramatically increase both the number and quality of pulsating white dwarf observations. + oai:arXiv.org:2512.15814v1 + astro-ph.IM + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Matt\'eo Blamart, Adrian Liu, Robert Brandenberger, Julian B. Mu\~noz, Bryce Cyr + Murat Uzundag, Ingrid Pelisoli, Stephane Charpinet, Alejandro H. Corsico, Leandro G. Althaus, V. Van Grootel, Suzanna Randall, Thomas Kupfer, Roberto Raddi - Rhea-RT: Dynamical impact of Central Molecular Zone conditions on ISM properties and stellar feedback coupling - https://arxiv.org/abs/2512.09981 - arXiv:2512.09981v1 Announce Type: new -Abstract: The Central Molecular Zone (CMZ) is an extreme star formation environment, characterized by higher density, higher turbulence, stronger orbital shear, and stronger magnetic field strength than the Solar neighborhood. Whether classical theories of star formation hold within this extreme environment is still debated. In order to assess the impact of these different conditions on the interstellar medium (ISM) and on star formation, we present radiation MHD arepo simulations of a Milky Way-type galaxy. We set up a high-resolution ($M_{\rm cell}=20$ M$_\odot$) region in a ring around the Solar radius, as well as in the barred region of the Galaxy to have a coherent comparison between the CMZ and the Solar neighborhood. Although the high densities and strong levels of turbulence influence star formation and feedback, we find that a key difference in the regulation of star formation between the two environments comes from the short orbital times and the strong shear present in the CMZ. In particular, we highlight the role of the quick dynamical decoupling of stars and gas that leads to periodic re-embedding events in the early lifetimes of radiating O stars. Young stellar associations get efficiently sheared apart such that the ISM is deprived of the compounding effect of radiation and supernovae in disrupting molecular clouds. This changes dramatically the evolution of giant molecular clouds and how feedback can regulate star formation in the CMZ. Stellar feedback is no longer directly coupled to the molecular cloud from which they formed and no strong and disruptive superbubbles can develop. Instead, the feedback rather acts as a background source of turbulence. - oai:arXiv.org:2512.09981v1 + Sailing to the next safe harbour in our trip to the early Universe: The massive star population of metal-poor galaxies + https://arxiv.org/abs/2512.15817 + arXiv:2512.15817v1 Announce Type: new +Abstract: Very metal-poor massive stars in the Local Group are our best proxies for the Universe's first stars, making them essential for modeling reionization and early galactic chemical evolution. Studying such stars in our Local Universe is key to extrapolating our knowledge to more distant regions, where individual massive stars cannot be resolved but are dynamically and chemically shaping their environments. The MUSE integral field spectrograph has transformed massive star studies in the Milky Way and Magellanic Clouds, but resolving star-forming galaxies containing very metal-poor stars is at the limit of the current field of view and sensitivity. Therefore, only small dedicated efforts of selected regions are studied, providing us with snapshots of low-metallicity massive stars rather than a comprehensive picture. This scarcity is a major bottleneck for understanding and sufficiently modelling the evolution and feedback of massive stars across cosmic time. We therefore envision a new generation of panoramic integral-field spectrographs and high multiplex multi-object spectrographs mounted on dedicated large optical telescopes. Such facilities will not only allow to resolve very-metal-pool galaxies, but further enable the systematic exploration of the massive stellar content across the entire Local Group, thereby reaching a new era in massive star studies and understanding. + oai:arXiv.org:2512.15817v1 + astro-ph.IM astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - R. G. Tress, N. Brucy, P. Girichidis, S. C. O. Glover, J. Goeller, M. Hirschmann, R. Klessen, T. Peter, J. Petersson, M. C. Sormani, L. Armillotta, C. D. Battersby, M. Donati, Z. X. Feng, J. D. Henshaw, D. R. Lipman, S. N. Longmore, F. Nogueras-Lara, V. M. Pelkonen, N. Peschken, M. A. Petkova, A. Plat, S. Reissl, R. Smith, J. D. Soler + N. Castro (Leibniz-Institut f\"ur Astrophysik Potsdam, Germany), M. Garcia (Centro de Astrobiolog\'ia, CSIC-INTA, Spain), A. Herrero (Departamento de Astrof\'isica, Universidad de La Laguna, Spain, Instituto de Astrof\'isica de Canarias, Spain), A. A. C. Sander (Zentrum f\"ur Astronomie der Universit\"at Heidelberg, Astronomisches Rechen-Institut, Germany), A. F. McLeod (Centre for Extragalactic Astronomy, Department of Physics, Durham University, UK, Institute for Computational Cosmology, Department of Physics, University of Durham, UK), M. M. Roth (Leibniz-Institut f\"ur Astrophysik Potsdam, Germany), I. Negueruela (Departamento de F\'isica Aplicada, Facultad de Ciencias, Universidad de Alicante, Spain, Instituto Universitario de Investigaci\'on Inform\'atica, Universidad de Alicante, Spain), J. S. Vink (Armagh Observatory, UK) - KURVS: chemical properties from multiple strong line calibrations for star-forming galaxies at $z\sim1.5$ - https://arxiv.org/abs/2512.09983 - arXiv:2512.09983v1 Announce Type: new -Abstract: Gas-phase oxygen abundance (metallicity) properties can be constrained through emission line analyses, and are of great importance to investigate galaxy evolution histories. We present an analysis of the integrated and spatially-resolved rest-frame optical emission line properties of the ionised gas in 43 star-forming galaxies at $z\sim1.5$ in the KMOS Ultra-deep Rotational Velocity Survey (KURVS). Using the [NII]$\lambda6584$/H$\alpha$ (N$_2$), ([OII]$\lambda\lambda3727,9+$[OIII]$\lambda\lambda4959,5007$)/H$\beta$ (R23), and for the first time [NII]$\lambda6584$/[OII]$\lambda\lambda3727,9$ (N$_2$O$_2$) indicators at this redshift, we measure the gas-phase metallicities and their radial gradients. On $\sim4$-kpc scales metallicity gradients measured from N$_2$O$_2$ and those measured from N$_2$ are in good agreement when considering the spatial distributions of dust in each galaxy, as parameterised by dust attenuation radial gradients. We report a nearly flat metallicity gradient distribution typically at $z\sim1.5$, with the 50th, 16th and 84th percentiles at $0.01$, $-0.03$, and $0.05$ dex kpc$^{-1}$, respectively. The findings agree well with previous observational studies and simulations at this epoch. We ascribe the observed negative metallicity gradients to a natural result from self-regulating systems, and the positive ones to potential galactic fountains and higher merger rates. - oai:arXiv.org:2512.09983v1 - astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Nova Explosions in 2040 + https://arxiv.org/abs/2512.15821 + arXiv:2512.15821v1 Announce Type: new +Abstract: Novae are thermonuclear explosions on the surface of accreting white dwarfs and are key laboratories for studying explosive nucleosynthesis, particle acceleration, shock physics, and binary evolution. Despite major progress driven by wide-field time-domain surveys and multi-wavelength facilities, our understanding of nova explosions remains limited by incomplete temporal coverage, heterogeneous spectroscopic follow-up, and poorly constrained ejecta properties. In this white paper we outline the open scientific questions that will define nova research in the 2040s, focusing on the mass, composition, geometry, and dynamics of the ejecta, the role of the underlying binary system, and the connection between nuclear burning, shocks, and emission across the electromagnetic spectrum. We argue that decisive progress requires rapid-response, high-cadence, multi-wavelength observations, anchored by systematic high-resolution optical and near-infrared spectroscopy from eruption to quiescence. Finally, we identify key technological requirements needed to enable transformative advances in the physics of nova explosions over the coming decades. + oai:arXiv.org:2512.15821v1 + astro-ph.IM + astro-ph.HE + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 10.1093/mnras/staf1919 - Zefeng Li, Ugn\.e Dudzevi\v{c}i\=ut\.e, Annagrazia Puglisi, Steven Gillman, A. Mark Swinbank, Luca Cortese, Ian Smail, Karl Glazebrook, Anna F. McLeod, Dominic J. Taylor, Roland Bacon, Christopher Harrison, Edo Ibar, Juan Molina, Danail Obreschkow, Tom Theuns + Alessandro Ederoclite (CEFCA), Domitilla De Martino (INAF-OAC), Paul Groot (SAAO, Department of Astronomy, University of Cape Town, Radboud University), Elena Mason (INAF-OATS), Gloria Sala (UPC, IEEC), Mart\'in Guerrero (IAA-CSIC), Thomas Kupfer (Texas Tech University, Hamburg Observatory, University of Hamburg), Anna Francesca Pala (ESO - Garching), Simone Scaringi (Durham University), Noel Castro Segura (University of Warwick) - Clues from $\mathcal{Q}$--A null test designed for line intensity mapping cross-correlation studies - https://arxiv.org/abs/2512.09984 - arXiv:2512.09984v1 Announce Type: new -Abstract: Estimating the auto power spectrum of cosmological tracers from line-intensity mapping (LIM) data is often limited by instrumental noise, residual foregrounds, and systematics. Cross-power spectra between multiple lines offer a robust alternative, mitigating noise bias and systematics. However, inferring the auto spectrum from cross-correlations relies on two key assumptions: that all tracers are linearly biased with respect to the matter density field, and that they are strongly mutually correlated. In this work, we introduce a new diagnostic statistic, \(\mathcal{Q}\), which serves as a data-driven null test of these assumptions. Constructed from combinations of cross-spectra between four distinct spectral lines, \(\mathcal{Q}\) identifies regimes where cross-spectrum-based auto-spectrum reconstruction is unbiased. We validate its behavior using both analytic toy models and simulations of LIM observables, including star formation lines ([CII], [NII], [CI],[OIII]) and the 21-cm signal. We explore a range of redshifts and instrumental configurations, incorporating noise from representative surveys. Our results demonstrate that the criterion \( \mathcal{Q} \approx 1 \) reliably selects the modes where cross-spectrum estimators are valid, while significant deviations are an indicator that the key assumptions have been violated. The \( \mathcal{Q} \) diagnostic thus provides a simple yet powerful data-driven consistency check for multi-tracer LIM analyses. - oai:arXiv.org:2512.09984v1 - astro-ph.CO + Accretion and Ejection Physics at High Time Resolution + https://arxiv.org/abs/2512.15832 + arXiv:2512.15832v1 Announce Type: new +Abstract: Accretion onto compact objects is one of the most fundamental phenomena in the astrophysics, powering some of the most luminous objects in the sky. Along with this, accretion has also a key impact on the evolution of the Universe, through the launch of powerful outflows that affect the surrounding medium. In the last years sub-second optical-infrared observations of accreting X-ray binaries have opened a new window in the study of inflow-outflow connection, discovering a wide range of previously unkown phenomena. Here we review the key open questions in accretion and ejection physics and discuss how a dedicated facility, equipped with photon-counting detectors and high spectral resolution from the UV to the mid-infrared, can enable transformative advances in our understanding of accretion processes. + oai:arXiv.org:2512.15832v1 astro-ph.IM - physics.data-an - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Debanjan Sarkar, Ella Iles, Adrian Liu + http://creativecommons.org/licenses/by/4.0/ + F. M. Vincentelli, P. Casella, A. Veledina, A. Ambrifi, M. C. Baglio, D. Buckley, N. Castro Segura, Y. Cavecchi, D. de Martino, M. del Santo, P. Gandhi, G. Iliano, R. La Paca, C. Malacaria, A. Marino, K. O'Brien, N. Rea, A. Sanna, S. Scaringi, T. Shahbaz, L. Zampieri - Orbital migration and heating history of the Galactic disc: a transition between the bimodal discs - https://arxiv.org/abs/2512.09987 - arXiv:2512.09987v1 Announce Type: new -Abstract: Stellar orbits in the Galactic disc evolve from their birth to the current shape through both radial migration and dynamical heating. The history of their secular evolution is imprinted in the current kinematics and age-metallicity distribution. We construct a chrono-chemo-dynamical model of the disc, incorporating inside-out growth, metallicity evolution, radial migration, and heating to fit the observed age-metallicity-kinematics distribution of LAMOST subgiant stars in both the low and high-$\alpha$ disc. By modelling all distribution parameters with spline fitting, we present the first non-parametric stellar migration and heating history of the Galaxy. We determine the heating-to-migration ratio, the ratio of the root-mean-square changes in radial/vertical and azimuthal actions, to be $\approx0.075$ for radial to azimuthal actions and $\approx0.015$ for vertical to azimuthal actions, implying a highly anisotropic diffusion in the action space. Furthermore, we identify a transition in radial migration efficiency coinciding with the transition moment of the bimodal disc, for which the radial migration was more efficient for the high-$\alpha$ disc than for the low-$\alpha$ disc. This transition may be attributed to two correlated scenarios: 1) a bar formation epoch accompanied by violent outward migration, and 2) a drop in the gas mass fraction in the disc when the low-$\alpha$ disc began to form. These findings offer further constraints on the formation mechanisms of bimodal discs, favouring the downsizing scenario. We also briefly discuss the connection between our results and recent high-redshift observations. In addition to the secular evolution history, our model maps the Milky Way ISM metallicity gradient at different lookback times, which we find has only varied a little (in the range of $-0.07~\rm to~-0.10~dex/kpc$) since disc formation. - oai:arXiv.org:2512.09987v1 - astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + The Simons Observatory: forecasted constraints on primordial gravitational waves with the expanded array of Small Aperture Telescopes + https://arxiv.org/abs/2512.15833 + arXiv:2512.15833v1 Announce Type: new +Abstract: We present updated forecasts for the scientific performance of the degree-scale (0.5 deg FWHM at 93 GHz), deep-field survey to be conducted by the Simons Observatory (SO). By 2027, the SO Small Aperture Telescope (SAT) complement will be doubled from three to six telescopes, including a doubling of the detector count in the 93 GHz and 145 GHz channels to 48,160 detectors. Combined with a planned extension of the survey duration to 2035, this expansion will significantly enhance SO's search for a $B$-mode signal in the polarisation of the cosmic microwave background, a potential signature of gravitational waves produced in the very early Universe. Assuming a $1/f$ noise model with knee multipole $\ell_{\rm knee} = 50$ and a moderately complex model for Galactic foregrounds, we forecast a $1\sigma$ (or 68% confidence level) constraint on the tensor-to-scalar ratio $r$ of $\sigma_r = 1.2\times10^{-3}$, assuming no primordial $B$-modes are present. This forecast assumes that 70% of the $B$-mode lensing signal can ultimately be removed using high resolution observations from the SO Large Aperture Telescope (LAT) and overlapping large-scale structure surveys. For more optimistic assumptions regarding foregrounds and noise, and assuming the same level of delensing, this forecast constraint improves to $\sigma_r = 7\times10^{-4}$. These forecasts represent a major improvement in SO's constraining power, being a factor of around 2.5 times better than what could be achieved with the originally planned campaign, which assumed the existing three SATs would conduct a five-year survey. + oai:arXiv.org:2512.15833v1 + astro-ph.CO + hep-ex + hep-th + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - HanYuan Zhang, Vasily Belokurov, Jason L. Sanders, N. Wyn Evans, David Chemaly, Daisuke Kawata, Natsuki Funakoshi, Neige Frankel, Sarah G. Kane, Sergey E. Koposov + The Simons Observatory Collaboration, I. Abril-Cabezas, S. Adachi, P. Ade, A. E. Adler, P. Agrawal, J. Aguirre, S. Aiola, T. Alford, A. Ali, D. Alonso, M. A. Alvarez, R. An, M. Aravena, K. Arnold, P. Ashton, F. Astori, Z. Atkins, J. Austermann, S. Azzoni, C. Baccigalupi, D. Baker, R. Balafendiev, A. Baleato Lizancos, D. Barron, P. Barry, J. Bartlett, A. Basyrov, N. Battaglia, E. S. Battistelli, R. Battye, A. Bayer, A. Bazarko, J. A. Beall, R. Bean, D. Beck, S. Beckman, J. Begin, A. Beheshti, B. Beringue, T. Bhandarkar, S. Bhimani, F. Bianchini, E. Biermann, M. Billi, S. Biquard, B. Bixler, L. Bizzarri, S. Boada, D. Boettger, B. Bolliet, J. R. Bond, J. Borrill, J. Borrow, C. Braithwaite, T. L. R. Brien, M. L. Brown, S. M. Bruno, S. Bryan, R. Bustos, H. Cai, E. Calabrese, V. Calafut, F. M. Carl, A. Carones, J. Carron, A. Challinor, E. Chamberlain, P. Chanial, N. Chen, K. Cheung, B. Chiang, Y. Chinone, J. Chluba, H. S. Cho, S. K. Choi, M. Chu, J. Clancy, S. E. Clark, P. Clarke, J. Cleary, D. L. Clements, J. Connors, C. Contaldi, G. Coppi, L. Corbett, N. F. Cothard, W. Coulton, D. Crichton, K. D. Crowley, K. T. Crowley, A. Cukierman, J. M. D'Ewart, K. Dachlythra, O. Darwish, R. Datta, S. Day-Weiss, T. de Haan, S. Desai, M. Devlin, L. Di Mascolo, S. Dicker, K. Ding, C. Doux, P. Dow, S. Doyle, C. J. Duell, S. M. Duff, A. J. Duivenvoorden, J. Dunkley, M. Duparc, D. Dutcher, R. D\"unner, M. Edenton, H. El Bouhargani, C. Embil Villagra, J. Errard, G. Fabbian, V. Fanfani, F. Farhadi Khouzani, G. S. Farren, J. Fergusson, S. Ferraro, R. Flauger, M. Forconi, A. Foster, K. Freese, J. C. Frisch, A. Frolov, G. Fuller, N. Galitzki, P. A. Gallardo, G. Galloni, J. T. Galvez Ghersi, K. Ganga, X. Garrido, E. Gawiser, M. Gerbino, R. Gerras, S. Giardiello, A. Gill, V. Gilles, U. Giri, E. Gleave, V. Gluscevic, N. Goeckner-Wald, S. Goldstein, J. E. Golec, S. Gordon, M. Gralla, S. Gratton, D. Green, J. C. Groh, C. Groppi, S. Grubb, Y. Guan, N. Gupta, J. E. Gu{\dh}mundsson, B. Hadzhiyska, S. Hagstotz, P. Hargrave, S. Haridas, K. Harrington, I. Harrison, M. Hasegawa, M. Hasselfield, V. Haynes, M. Hazumi, A. He, E. Healy, S. W. Henderson, B. S. Hensley, E. Hertig, C. Herv\'ias-Caimapo, M. Higuchi, C. A. Hill, J. C. Hill, M. Hilton, A. D. Hincks, G. Hinshaw, R. Hlo\v{z}ek, A. Y. Q. Ho, S. Ho, S. P. Ho, T. D. Hoang, J. Hoh, J. Holder, J. Hood, E. Hornecker, A. L. Hornsby, S. C. Hotinli, Z. Huang, Z. B. Huber, J. Hubmayr, K. Huffenberger, A. Hughes, J. P. Hughes, A. Idicherian Lonappan, M. Ikape, K. Inaba, K. Irwin, J. Iuliano, A. H. Jaffe, B. Jain, D. Jain, H. T. Jense, O. Jeong, A. Johnson, B. R. Johnson, M. Johnson, M. E. Jones, N. Joshi, B. Jost, W. Kabalan, V. Kabra, D. Kaneko, J. Kania, E. D. Karpel, Y. Kasai, N. Katayama, B. Keating, B. Keller, R. Keskitalo, A. A. Khatua, J. Kim, T. Kisner, K. Kiuchi, K. Knowles, A. M. Kofman, Y. Koizumi, B. J. Koopman, A. Kosowsky, R. Kou, N. Krachmalnicoff, D. Kramer, A. Krishak, A. Krolewski, A. Kusaka, A. Kusiak, Y. Kvasiuk, P. La Plante, A. La Posta, A. Lagu\"e, A. Lai, J. Lashner, M. Lattanzi, A. Lee, E. Lee, J. Leech, L. Legrand, C. Lessler, J. S. Leung, A. Lewis, Y. Li, Z. Li, M. Limon, L. Lin, E. Linder, M. Link, J. Liu, Y. Liu, J. Lloyd, J. Lonergan, T. Louis, T. Lucas, M. Ludlam, M. Lungu, M. Lyons, N. MacCrann, A. MacInnis, M. Madhavacheril, D. Mak, F. Maldonado, M. Mallaby-Kay, A. Manduca, A. Mangu, H. Mani, A. S. Maniyar, G. A. Marques, P. Masson, J. Mates, J. Mathewson, T. Matsumura, P. Mauskopf, A. May, N. McCallum, H. McCarrick, F. McCarthy, M. McCulloch, J. McMahon, P. D. Meerburg, Y. Mehta, J. Melin, E. Meulbroek, J. Meyers, A. Middleton, Y. Miki, A. Miller, M. Mirmelstein, Y. Mizozoe, B. Mohammadian, G. Montefalcone, K. Moodley, J. Moore, T. Morris, M. Morshed, T. Morton, E. Moser, T. Mroczkowski, M. Murata, J. Myers, M. M\"unchmeyer, S. Naess, H. Nakata, T. Namikawa, M. Nashimoto, F. Nati, P. Natoli, M. Negrello, S. K. Nerval, L. Newburgh, D. V. Nguyen, A. Nicola, M. D. Niemack, H. Nishino, Y. Nishinomiya, A. Novelli, S. O'Neill, N. Okumoto, A. Orlando, J. Orlowski-Scherer, L. Pagano, L. A. Page, S. Pandey, A. Papageorgiou, I. Paraskevakos, B. Partridge, D. Patel, R. Patki, S. Paulino Korte, M. Peel, K. Perez Sarmiento, F. Perrotta, P. Phakathi, L. Piccirillo, E. Pierpaoli, T. Pinsonneault-Marotte, G. Pisano, J. Pitocco, D. Poletti, C. Popik, B. Prasad, R. Puddu, G. Puglisi, F. J. Qu, F. Rahman, M. J. Randall, C. Ranucci, C. Raum, R. Reeves, C. L. Reichardt, M. Remazeilles, X. Ren, Y. Rephaeli, D. Riechers, B. Reid Guachalla, A. Rizzieri, J. Robe, M. F. Robertson, N. Robertson, K. Rogers, F. Rojas, A. Romero, E. Rosenberg, A. Rotti, S. Rowe, A. Roy, S. Sadeh, N. Sailer, K. Sakaguri, T. Sakuma, Y. Sakurai, M. Salatino, G. H. Sanders, D. Sasaki, M. Sathyanarayana Rao, T. P. Satterthwaite, L. Saunders, L. Scalcinati, E. Schaan, B. Schmitt, M. Schmittfull, N. Sehgal, J. Seibert, Y. Seino, U. Seljak, S. Shaikh, E. Shaw, P. Shellard, B. Sherwin, M. Shimon, J. E. Shroyer, C. Sierra, J. Sievers, C. Sif\'on, P. Sikhosana, M. Silva-Feaver, S. M. Simon, A. Sinclair, K. Smith, W. Sohn, X. Song, R. F. Sonka, T. Souverin, J. Spisak, S. T. Staggs, G. Stein, J. R. Stevens, R. Stompor, E. Storer, R. Sudiwala, Y. Sueno, J. Sugiyama, P. Suman, K. M. Surrao, S. Sutariya, A. Suzuki, J. Suzuki, O. Tajima, R. Takaku, S. Takakura, A. Takeuchi, I. Tansieri, A. C. Taylor, G. Teply, T. Terasaki, A. Thomas, D. B. Thomas, R. Thornton, P. Timbie, H. Trac, T. Tsan, E. Tsang King Sang, C. Tucker, J. Ullom, L. Vacher, L. Vale, A. van Engelen, J. Van Lanen, J. van Marrewijk, D. D. Van Winkle, C. Vargas, E. M. Vavagiakis, I. Veenendaal, C. Verg\`es, A. Villarrubia Aguilar, M. Vissers, M. Vi\~na, K. Wagoner, S. Walker, L. Walters, Y. Wang, B. Westbrook, J. Williams, P. Williams, J. Wilson, H. Winch, E. J. Wollack, K. Wolz, J. Wong, Z. Xu, K. Yamada, E. Young, B. Yu, C. Yu, G. Zagatti, M. Zannoni, W. Zhang, K. Zheng, N. Zhu, A. Zonca, I. Zubeldia - ClearPotential: Revealing Local Dark Matter in Three Dimensions - https://arxiv.org/abs/2512.09989 - arXiv:2512.09989v1 Announce Type: new -Abstract: We present ClearPotential, a data-driven, three-dimensional measurement of the gravitational potential of the local Milky Way using unsupervised machine learning, without the symmetry assumptions, specific functional forms, and binning required in previous work. The potential is modeled as a neural network, optimized to solve the equilibrium collisionless Boltzmann equation for the observed phase space density of Gaia DR3 Red Clump stars within 4 kpc of the Sun. This density is obtained from data using normalizing flows, and our unsupervised solution to the Boltzmann equation automatically corrects for selection effects from crowding and the dust-driven extinction of starlight. Our fully-differentiable model of the gravitational potential allows us to map the acceleration and mass density of the Galaxy in the volume around the Sun, including in the dust-obscured disk towards the Galactic Center. We determine the dark matter density at the Solar radius to be $(0.84 \pm 0.08)\times 10^{-2}\,{M}_\odot/{\rm pc}^3$, and analyze the structure of the dark matter halo. We find strong evidence for a tilted oblate halo, weak preference for a cored inner profile, and the strongest constraints to date on a possible dark matter disk. We place a bound on the timescale of disequilibrium in the local Milky Way, and find mild evidence for disequilibrium using independent acceleration measurements from timings of binary pulsar systems. This work provides the clearest map of the local Galactic potential to date and marks an important step in the era of data-driven astrometry. - oai:arXiv.org:2512.09989v1 + What Builds and Quenches the Most Massive Galaxies in the Early Universe? + https://arxiv.org/abs/2512.15836 + arXiv:2512.15836v1 Announce Type: new +Abstract: The first few billion years of cosmic history witnessed the rapid emergence of the most massive galaxies, yet their true space density, baryon assembly pathways, and early quenching mechanisms remain poorly constrained. Current surveys lack the wide-field, rest-frame FIR sensitivity needed to obtain a complete census of massive systems and to trace their cold gas, dust, and diffuse emission on galactic and circumgalactic scales. A next-generation facility with a very large aperture, wide field of view, and high mapping speed is essential to carry out deep, degree-scale rest-frame FIR surveys. Such capabilities are required to determine how common massive galaxies are, how they assemble their baryons, and what physical processes drive their early transformation and quenching. + oai:arXiv.org:2512.15836v1 + astro-ph.IM astro-ph.GA - hep-ph - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Eric Putney, David Shih, Sung Hak Lim, Matthew R. Buckley + Mengyuan Xiao, Longji Bing, Guilaine Lagache, Miroslava Dessauges-Zavadsky, Olivier Ilbert, Benjamin Magnelli, Pascal A. Oesch - The mysterious Globular Cluster population of MATLAS-2019 - https://arxiv.org/abs/2512.09990 - arXiv:2512.09990v1 Announce Type: new -Abstract: MATLAS-2019 (also known as NGC5846-UDG1) has attracted significant attention due to the ongoing debate surrounding its Globular Cluster (GC) population, with several studies addressing the issue yet reaching little consensus. In this paper we take advantage of HST's multi-wavelength coverage (F475W, F606W and F814W observations) with the addition of deep u-band imaging from Gran Telescopio de Canarias, to perform the most detailed study and estimation to date of the GC population of the ultra-diffuse galaxy MATLAS-2019. The improved constraints provided by the combination of high spatial resolution and better coverage of the GC spectral energy distribution has allowed us to obtain a clean sample of GCs in this galaxy. We report a number of 33+-3 GCs in MATLAS-2019, supporting the previous lower estimates for this galaxy. The GC population of this galaxy is highly concentrated with ~80% of the GCs inside the effective radius (Re) of the galaxy and the GC half-number radius Re,GC is 0.7Re. Using the GC-Halo mass relation, we estimate a halo mass for MATLAS-2019 of (1.14+-0.1)x10**11 solar masses. The GC luminosity function and the distribution of effective radii of the GCs favour a distance to the galaxy of 20.0+-0.9 Mpc. In agreement with previous findings, we find that the distribution of GCs is highly asymmetric even though the distribution of stars in the galaxy is symmetric. This suggests that assumptions about the symmetry of the GC distribution may be incorrect when used to calculate the number of GCs with such low statistics. - oai:arXiv.org:2512.09990v1 + Galaxies as stochastic systems: why the next breakthrough in galaxy evolution requires one hundred million spectra + https://arxiv.org/abs/2512.15841 + arXiv:2512.15841v1 Announce Type: new +Abstract: Each galaxy is observed only once along its life, making galaxy evolution fundamentally an inverse statistical problem: time-dependent physics must be inferred from ensembles of single-epoch snapshots. To move beyond descriptive scaling relations toward physical regulation mechanisms of star formation, quenching, chemical enrichment and black hole growth, galaxies must be treated as realizations of a stochastic process whose hyper-parameters (e.g., correlation timescales, burstiness, duty cycles) are inferred hierarchically. This demands both depth and scale: continuum S/N sufficient for absorption-line ages and chemistry, and samples far larger than those in SDSS, DESI, 4MOST or MOONS, which provide either depth or size but not both across $0<z<3$. Once the relevant axes of mass, redshift, environment, structure and evolutionary phase are populated, the requirement naturally rises from $10^7$ to $\sim10^8$ galaxies. This is the regime where stochastic hyper-parameters can be well constrained and where comparisons to simulations and cosmological forward models become limited by theory rather than observations. We outline the science enabled by such a programme and the corresponding requirements for a future ESO wide-field spectroscopic facility capable of delivering tens to hundreds of millions of rest-UV-optical spectra over $0\lesssim z\lesssim3$. + oai:arXiv.org:2512.15841v1 + astro-ph.IM astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Sergio Guerra Arencibia, Mireia Montes, Giulia Golini, Ignacio Trujillo + Sandro Tacchella, Vasily Belokurov, Harry T. J. Bevins, Roberto Maiolino, Hiranya V. Peiris, Lucia Pozzetti, Mark T. Sargent - Observational constraints on 3-forms dark energy - https://arxiv.org/abs/2512.09991 - arXiv:2512.09991v1 Announce Type: new -Abstract: 3-forms are natural candidates for describing the late-time accelerated expansion of the Universe, as they can inherently reproduce a positive cosmological constant when lacking an evolving potential. When such a potential is present, a 3-form field may exhibit either quintessence-like or phantom-like behaviour. In this paper, we consider a 3-form model with a Gaussian potential, which features stable, ghost-free phantom-like behaviour within its convergence region and leads to an LSBR late-time attractor. We constrain this model observationally by performing a Markov Chain Monte Carlo (MCMC) analysis employing a comprehensive cosmological dataset, including Planck PR4 cosmic microwave background (CMB) data, DESI DR1 baryon acoustic oscillation (BAO) measurements, Pantheon+ Type Ia supernovae data, low-$z$ Cepheid calibrators, and DES Y1 large-scale structure observations. We demonstrate that the 3-form model successfully increases the predicted Hubble parameter of CMB and BAO data from $67.89\pm0.36{\rm km/s/Mpc}$ of $\Lambda$CDM model to $68.29^{+0.56}_{-0.61}{\rm km/s/Mpc}$ without fine-tuning of the model parameters, thus reducing the tension with the late-time observation. Furthermore, we verify the sub-dominance of the 3-form field perturbation via both analytical and numerical analyses. Thus, the 3-form field does serve as a promising candidate of phantom-like dark energy from both theoretical and observational points of view. - oai:arXiv.org:2512.09991v1 - astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + A JWST Transmission Spectrum of the Temperate Sub-Neptune TOI-732 c + https://arxiv.org/abs/2512.15844 + arXiv:2512.15844v1 Announce Type: new +Abstract: In recent years, JWST has facilitated detections of carbon-bearing molecules in the atmospheres of temperate sub-Neptunes orbiting M dwarfs, ushering in a new era in the characterization of this intriguing planetary regime. We report the transmission spectrum of the temperate sub-Neptune TOI-732 c, observed with JWST NIRISS, NIRSpec G395H and MIRI LRS between 0.9-12 $\mu$m. The observations provide evidence for methane (CH$_4$) in a H$_2$-rich atmosphere, at a volume mixing ratio of $\sim$1\%, and non-detection of NH$_3$ and HCN, along with nominal constraints on other prominent molecules H$_2$O, CO and CO$_2$, which are typically expected in H$_2$-rich atmospheres. We conduct a comprehensive survey of 250 chemical species and find moderate to strong evidence (up to $\ln B\sim 5.9$, $3.9\sigma$) for additional absorption due to one or more complex molecules including higher-order hydrocarbons and/or sulfur-bearing molecules. The spectral features are strongly degenerate among these molecules and with methane, which we find at $\ln B=3.2-8.8$ (up to $3.0-4.6$$\sigma$) significance. Two complex molecules are preferred with at least moderate evidence ($\ln B \gtrsim 2.5$) in both the near- and mid-infrared, while several others show such evidence in at least one of the two wavelength ranges. The preferred molecules are found in trace quantities on Earth, with no significant sources identified in other planetary atmospheres, requiring future work to assess their physical plausibility in this planet. Future observations are required to resolve the degeneracies and place more robust constraints on these species. We highlight the need for further theoretical and experimental work to robustly characterize the atmospheric and internal composition of TOI-732 c and similar sub-Neptunes. + oai:arXiv.org:2512.15844v1 + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Mariam Bouhmadi-L\'opez, Hsu-Wen Chiang, Carlos G. Boiza, Pisin Chen + http://creativecommons.org/licenses/by/4.0/ + Frances E. Rigby, Nikku Madhusudhan, Subhajit Sarkar, Lorenzo Pica-Ciamarra, M{\aa}ns Holmberg, Julianne I. Moses - Characterizing the Roman Grism Redshift Efficiency of Type Ia Supernova Host Galaxies for the High-Latitude Time-Domain Survey - https://arxiv.org/abs/2512.09993 - arXiv:2512.09993v1 Announce Type: new -Abstract: The High-Latitude Time-Domain Survey (HLTDS) for the Nancy Grace Roman Space Telescope (Roman) will discover thousands of high redshift Type Ia supernovae (SNeIa) to make generation-defining cosmological constraints on dark energy. To construct the Roman SN Hubble diagram, a strategy to obtain redshifts must be determined. While the nominal HLTDS will use only the Roman prism, in this work we consider the utility of the Roman grism observations from overlap with the High-Latitude Wide-Area Survey for SNIa cosmology. We determine a galaxy grism redshift recovery rate by simulating dispersed grism images and measuring redshifts with the Grizli software, obtaining an $H$-band 50% redshift recovery at magnitude 20.61 and 90% recovery at magnitude 19.27. To estimate the total number of spectroscopic redshifts expected for Roman SN cosmology, we also consider a Roman prism SN redshift efficiency and a ground-based telescope redshift efficiency for host-galaxies. We apply these redshift efficiencies to SNIa catalog level simulations and predict that $\sim$6800 SNe will have a SN or host spectroscopic redshift. Second, we evaluate the size of potential systematics related to modeling the grism redshift efficiency by considering the impact of additional dependencies on stellar mass and host galaxy color. We estimate the largest potential size of this systematic to be 0.0066$\pm$0.002 and -0.0266$\pm$0.007, roughly 42.9 and 49.6% of the statistical uncertainty for $w_0$ and $w_a$ respectively. Lastly, we consider the effects of assuming different redshift sources on the HLTDS survey strategy optimization by measuring relative changes to the dark energy Figure of Merit. - oai:arXiv.org:2512.09993v1 - astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + Self-confinement of relativistic pair beams in magnetized interstellar plasmas: the case of pulsar X-ray filaments + https://arxiv.org/abs/2512.15847 + arXiv:2512.15847v1 Announce Type: new +Abstract: The observation of filamentary X-ray structures near bow-shock pulsar wind nebulae (PWNe) -- such as the Guitar, Lighthouse, and PSR J2030$+$4415 nebulae -- and of slow-diffusion regions around pulsars like Geminga, Monogem, and PSR J0622$+$3749, challenges the standard picture of cosmic-ray transport in the interstellar medium, implying a diffusion coefficient two orders of magnitude smaller than the Galactic average. The suppressed diffusion can be attributed to self-generated magnetic turbulence, driven -- via the non-resonant streaming instability -- by electron--positron pairs escaping the PWNe. This instability requires a net current, yet the beam of escaping pairs is expected to be charge-neutral. We show that a charge-neutral pair beam propagating through an electron--proton plasma can spontaneously generate a net current. Using fully kinetic two- and three-dimensional particle-in-cell simulations with realistic mass ratio, we find that beam electrons get focused into self-generated magnetic filaments produced by the nonlinear evolution of the Weibel instability, while beam positrons remain unconfined. The resulting net (positron) current drives the non-resonant streaming instability, further amplifying the magnetic field. This mechanism provides a pathway for the onset of charge asymmetries in initially charge-neutral pair beams and for the growth of magnetic fluctuations that efficiently scatter the beam particles, with implications for the formation of X-ray filaments and, more broadly, for particle self-confinement in TeV halos around PWNe. + oai:arXiv.org:2512.15847v1 + astro-ph.HE + physics.plasm-ph + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - R. C. Chen, Z. Guo, D. Scolnic, B. Joshi, R. Kessler, L. Galbany, R. Hounsell, D. M. Markoff, B. M. Rose, D. Rubin, the Roman Supernova Cosmology Project Infrastructure team + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Luca Orusa, Lorenzo Sironi - GA-NIFS: Powerful and frequent outflows in moderate-luminosity AGN at $z\sim3-6$ - https://arxiv.org/abs/2512.09996 - arXiv:2512.09996v1 Announce Type: new -Abstract: The period between z ~ 3-6, a key transformational phase in galaxy evolution preceding `cosmic noon' (z ~ 1-3), is very poorly explored in terms of feedback from AGN acting through gas outflows. In this work, we study the properties of outflows in AGN (mostly X-ray-selected) from the GOODS-S field, exploiting JWST NIRSpec IFU observations as part of the GA-NIFS GTO survey. Together with its twin sub-sample from COSMOS reported in a previous GA-NIFS work, this constitutes the largest spatially resolved sample of AGN outflows at these redshifts to date, comprising 16 targets with outflows (out of a total of 19 AGN), and probes the unexplored regime of AGN at z ~ 3-6 with bolometric luminosities ~$10^{45-46}$ erg/s. We mapped the rest-optical ionised gas emission lines at sub-kpc scales and spectrally isolated the broad wings tracing fast outflows from the gas at rest in the host galaxies. The incidence of ionised outflows in the GOODS-S + COSMOS GA-NIFS sample is high (>75\%), among the highest at any redshift. We inferred outflow velocities between ~600-2000 km/s, maximum radii of <1-4 kpc, and ionised gas mass outflow rates of ~0.1-100 $M_\odot$/yr, which in some cases can exceed the host galaxy star formation rate (SFR). We find that the outflow properties inferred for the GOODS-S + COSMOS GA-NIFS AGN sample and their relations with $L_{\rm bol}$ and SFR generally align with those observed for other spatially resolved literature samples of AGN outflows across different redshifts and AGN luminosities. Nonetheless, after accounting for any luminosity bias, our analysis suggests a cosmic evolution of the outflow properties, with higher median mass outflow rates (and possibly also mass loading factors) at higher redshifts, especially at z>3, indicating that AGN outflows were stronger in the early Universe than at later times, and thus potentially more capable of affecting their host galaxy. - oai:arXiv.org:2512.09996v1 - astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Revealing Callisto's Near Subsurface Thermophysical Properties with ALMA Calibration Data + https://arxiv.org/abs/2512.15850 + arXiv:2512.15850v1 Announce Type: new +Abstract: Thermal images at different wavelengths probe varying subsurface depths of planetary bodies, and therefore can inform us about their compositions, thermophysical properties, and impact histories. We identified six archival observations of Callisto obtained by the Atacama Large Millimeter/submillimeter Array (ALMA) between 2012 July 17 and 2012 November 4 at wavelengths of 0.43-0.47 mm (701.9-641.5 GHz). These wavelengths are shorter than those of nearly all other Callisto ALMA data and are sensitive to subsurface emission at depths (the upper ~cm) between those sounded by millimeter and infrared observations. We estimate the disk-averaged brightness temperature as 133$\pm$15 K, and use a thermophysical mixture model to find that Callisto's thermal emission is best fit by a ~50-50% two-component thermal inertia mixture of $\Gamma_{\text{low}}$~15-40 and $\Gamma_{\text{high}}$~1200-2000 J m$^{-2}$ K$^{-1}$ s$^{-1/2}$, consistent with recent ALMA observations of Callisto at longer wavelengths. Finally, we present several previously unpublished Galileo Photopolarimeter-Radiometer (PPR) observations of Callisto and derive thermal inertia and spectral emissivity maps using the same model. Altogether, these ALMA and PPR maps improve our understanding of the thermal properties and spatial distribution of Callisto's shallow subsurface regolith, and demonstrate the value of ALMA flux density calibrator data for extending frequency coverage of existing science data. + oai:arXiv.org:2512.15850v1 + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Giacomo Venturi, Stefano Carniani, Elena Bertola, Chiara Circosta, Eleonora Parlanti, Michele Perna, Santiago Arribas, Torsten B\"oker, Andrew Bunker, St\'ephane Charlot, Francesco D'Eugenio, Roberto Maiolino, Bruno Rodr\'iguez del Pino, Hannah \"Ubler, Giovanni Cresci, Gareth C. Jones, Nimisha Kumari, Isabella Lamperti, Madeline A. Marshall, Jan Scholtz, Sandra Zamora + Cole Meyer, Maria Camarca, Katherine de Kleer, Alexander Thelen, Christopher Chyba, Bryan Butler - Transient protostellar cores in high mass star forming regions revealed by time-resolved synthetic imaging of dust emission - https://arxiv.org/abs/2512.09998 - arXiv:2512.09998v1 Announce Type: new -Abstract: The connection between dense gas cores and their infant protostars is key to understanding how stars form in molecular clouds. In this paper we investigate the properties, persistence, and protostellar content of cores that would be identified by a dendrogram analysis of 1.3 mm ALMA images. We use a time series of synthetic images produced by post-processing a simulation of star formation in a massive globally collapsing clump, with polaris to calculate dust radiative transfer and CASA to generate synthetic ALMA data. Identifying sinks in the simulation with protostars, we find that most dendrogram-identified cores do not contain any protostars, with many cores being transient features associated with clumpy flow along feeder filaments. Cores with protostars generally host <4, and protostellar mass is not strongly correlated with the mass of the parent cores due to their transience and shifting boundaries. Calculating observationally-relevant intensity-weighted average temperatures for all cores, we find that even at early times the core temperature distribution spans tens of Kelvin, and its width increases with time. The 1.3 mm peak and integrated intensity of the brightest mm core do not increase monotonically as the most massive associated protostar grows, indicating it cannot be assumed that brighter mm sources host more massive protostars. Leveraging the time domain, we test observational properties that have been proposed as potential evolutionary indicators and find that only the total 1.3 mm flux density of the region, the total 1.3 mm flux density in cores, and the number of cores show strong, statistically significant correlation with time. - oai:arXiv.org:2512.09998v1 + From "The Cliff" to "Virgil": Mapping the Spectral Diversity of Little Red Dots with JWST/NIRSpec + https://arxiv.org/abs/2512.15853 + arXiv:2512.15853v1 Announce Type: new +Abstract: One of JWST's most unexpected discoveries is the emergence of "Little Red Dots'' (LRDs): compact sources at $z \gtrsim 3$ with blue rest-frame UV continua, red optical slopes, and broad Balmer emission lines that challenge standard models and suggest a population of early, unusual active galactic nuclei (AGNs). Using a comprehensive photometric selection and public NIRSpec/PRISM spectroscopy across six JWST deep fields, we identify a large sample of 118 LRDs with high-S/N spectra, enabling a population-wide analysis of their UV--optical continuum and emission lines. We find clear correlations between rest-frame color ([0.3-0.9\,$\mu$m]) and slopes: bluer LRDs have blue UV slopes ($\beta_{\nu,\mathrm{UV}} \sim 0.3$) and red optical slopes, while redder LRDs exhibit redder UV slopes ($\beta_{\nu,\mathrm{UV}} \sim 1.1$). The continuum shape shows a similar trend: redder LRDs display prominent Balmer breaks and curvature, while bluer LRDs follow power-law-like optical SEDs. From literature compilations, $\sim$60% of known broad-line AGNs satisfy our LRD criteria, and up to 90% of LRDs show broad Balmer lines. Emission-line diagnostics reveal a shift from high H$_{\alpha}$/H$_{\beta}$ and low [OIII]$\lambda5007$/H$_{\beta}$ in redder LRDs to the opposite in bluer ones, along with stronger narrow-line equivalent widths, suggesting a transition from AGN- to host-dominated emission. We fit the spectra with a two-component model combining a gas-enshrouded black hole (BH) and a galaxy host. Redder LRDs require higher-luminosity, unreddened BHs and modestly reddened hosts; bluer LRDs require lower-luminosity, reddened BHs and dust-free galaxies. This framework reproduces the diversity in colors and spectral shape by varying BH luminosity, obscuration, and host-to-BH luminosity ratio. + oai:arXiv.org:2512.15853v1 astro-ph.GA - astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Camilo H. Pe\~naloza, Rowan J. Smith, Claudia J. Cyganowski, Gwenllian M. Williams, Michael C. Logue, Todd R. Hunter, Jiancheng Feng + http://creativecommons.org/licenses/by/4.0/ + Guillermo Barro, Pablo G. Perez-Gonzalez, Dale Kocevski, Jonathan R. Trump, Mark Dickinson, Pablo Arrabal Haro, Madisyn Brooks, Steven L. Finkelstein, Maximilien Franco, Mauro Giavalisco, Norman A. Grogin, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Rebecca L. Larson, Gene C. K. Leung, Ray A. Lucas, Elizabeth J. McGrath, Casey Papovich, Borja Perez-Diaz, Elizabeth Taylor, Roberta Tripodi, L. Y. Aaron Yung - The Space-Based Time-Domain Revolution in Astrophysics - https://arxiv.org/abs/2512.10002 - arXiv:2512.10002v1 Announce Type: new -Abstract: Space-based time-domain telescopes such as CoRoT, Kepler/K2 and TESS have profoundly impacted astrophysics over the past two decades. Continuous light curves with high cadence and high photometric precision are now available for millions of sources within our galaxy and beyond. In addition to revolutionizing exoplanet science, the data have enabled breakthroughs ranging from the solar system to stellar interiors, the transient universe, and active galaxies. The key summary points of this review are: (1) Stellar astrophysics has been transformed by the ability to probe the internal structures of stars, test the physics of stellar convection, connect stellar rotation and magnetic activity, and reveal complex variability in young stars. (2) Ages of stellar populations probe the formation history of our Milky Way, and binary star variability enables the detection of "dark" galactic populations such as solar-mass black holes and neutron stars. (3) Early-time observations of explosive transients provide new insights into the progenitors of supernovae, while the quasi-periodic variability of galaxies probes the physics of accretion processes onto supermassive black holes and the tidal disruption of stars. (4) Observations of solar system objects reveal asteroid compositions through their rotation periods and amplitudes, constrain the cloud structure of ice giants, and allow the discovery of new objects in the outer solar system. (5) Open data policies and software have contributed to remarkable scientific productivity and enabled discoveries by citizen scientists, including new exoplanets and exotic variability in mature Sun-like stars. - oai:arXiv.org:2512.10002v1 - astro-ph.SR - astro-ph.EP - astro-ph.GA - astro-ph.HE - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + The AIDA-TNG project: 3D halo shapes + https://arxiv.org/abs/2512.15856 + arXiv:2512.15856v1 Announce Type: new +Abstract: Context. The shapes of dark matter halos can be used to constrain the fundamental properties of dark matter. In standard Cold Dark Matter (CDM) cosmologies, halos are typically triaxial, with a preference for prolate configurations, particularly at low masses and high redshift. Aims. We focus on the characterization of total matter 3D shape in alternative dark matter models, such as Self-Interacting Dark Matter (SIDM) and Warm Dark Matter (WDM). These scenarios predict different structural properties due to collisional effects or the suppression of small-scale power. Methods. We measure the different halo component shapes - dark matter, stars and gas - at various radii from the center in the AIDA-TNG (Alternative Interacting Dark Matter and Astrophysics - TNG), which is a suite of high-resolution cosmological simulations built upon the IllustrisTNG framework. The intent is to systematically study how different dark matter models - specifically, SIDM and WDM - affect galaxy formation and the structure of dark matter halos, when realistic baryonic physics is also included. Results. SIDM models tend to produce rounder and more isotropic halos, especially in the inner regions, as a result of momentum exchange between dark matter particles. WDM halos are also slightly more spherical than their CDM counterparts, and are typically less concentrated. In all cases, the inclusion of self-consistent baryonic physics makes the central regions of all halos rounder, while still revealing clear distinctions among the various dark matter models. Conclusions. The general framework presented in this work, based on the 3D halo shape, can be useful to interpret multi-wavelength data analyses of galaxies and clusters. + oai:arXiv.org:2512.15856v1 + astro-ph.CO + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Daniel Huber + C. Giocoli, G. Despali, L. Moscardini, M. Meneghetti, R. K. Sheth, A. Pillepich, M. Vogelsberger - Detailed Chemical Abundance Analysis of the Brightest Stars in the Turranburra and Willka Yaku Stellar Streams - https://arxiv.org/abs/2512.10003 - arXiv:2512.10003v1 Announce Type: new -Abstract: We present a detailed chemical abundance analysis of the three brightest known stars from each of the Turranburra and Willka Yaku stellar streams using high-resolution Magellan/MIKE spectra. Abundances for 27 elements, ranging from carbon to dysprosium, were derived. Our results support the original classification that Turranburra, with a low average metallicity of $\mathrm{[Fe/H]=-2.45} \pm 0.07$, likely originates from a dwarf-galaxy progenitor. Willka Yaku has a low average metallicity of $\mathrm{[Fe/H]=-2.35 \pm 0.03}$ with a small scatter in the abundances, consistent with a globular cluster progenitor as suggested by previous studies. Both streams exhibit mild enhancements in neutron-capture elements, with averages of $\mathrm{[Eu II/Fe]}=$ $0.47 \pm{0.09}$ for Turranburra and $0.44 \pm{0.05}$ for Willka Yaku, consistent with enrichment from an $r$-process event. A similar enrichment is observed in other stellar streams, and we further discuss this signature as it relates to the potential enrichment histories of these two streams. - oai:arXiv.org:2512.10003v1 - astro-ph.SR - astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Hunting exomoons with a kilometric baseline interferometer + https://arxiv.org/abs/2512.15858 + arXiv:2512.15858v1 Announce Type: new +Abstract: Despite numerous search campaigns based on a diverse set of observational techniques, exomoons - prospective satellites of extrasolar planets - remain an elusive and hard-to-pin-down class of objects. Yet, the case for intensifying this search is compelling: as in the Solar System, moons can act as proxies for studying planet formation and evolution, provide direct clues as to the migration history of the planetary hosts and, in favourable cases, offer potentially habitable environments. Here, we present an investigation into how the search for exomoons would benefit from a new interferometric facility operating in the optical wavelength domain and leveraging baselines substantially longer than the ones the VLTI is currently equipped with. We find that an interferometer providing an astrometric precision of 1$\,\mu$as would be able to robustly detect Earth-mass and sub-Earth-mass exomoons on dynamically stable orbits around Jupiter-like planets at distances between 50 and 200 pc. + oai:arXiv.org:2512.15858v1 + astro-ph.IM + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kaitlin B. Webber, Terese T. Hansen, Jennifer L. Marshall, Alexander P. Ji, Ting S. Li, Gary S. Da Costa, Lara R. Cullinane, Denis Erkal, Sergey E. Koposov, Kyler Kuehn, Geraint F. Lewis, Dougal Mackey, Sarah L. Martell, Andrew B. Pace, Nora Shipp, Jeffrey D. Simpson, Zhen Wan, Daniel B. Zucker, Victor A. Alvarado, Joss Bland-Hawthorn, Guilherme Limberg, Gustavo E. Medina, Sam A. Usman + http://creativecommons.org/licenses/by/4.0/ + Thomas O. Winterhalder, Antoine M\'erand, Sylvestre Lacour, Jens Kammerer, Guillaume Bourdarot, Frank Eisenhauer - Validation of a Third Earth-sized Planet in the TOI-2267 Binary System - https://arxiv.org/abs/2512.10007 - arXiv:2512.10007v1 Announce Type: new -Abstract: We report the validation of a third terrestrial exoplanet in the nearby (22 pc) TOI-2267 system. TOI-2267 is a binary system with stellar components TOI-2267A (M5, 3030 K) and TOI-2267B (M6, 2930 K), with an on-sky separation of 0.$^{\prime\prime}$384 (8 au projected separation). TOI-2267 hosts two Earth-sized planets (TOI-2267 b, $1.00\pm0.11 R_{\oplus}$, and TOI-2267 c, $1.14\pm0.13 R_{\oplus}$, if orbiting the primary star; or $1.22\pm0.29 R_{\oplus}$ and $1.36\pm0.33 R_{\oplus}$, respectively, if orbiting the secondary star) with orbital periods of 2.3 and 3.5 days. This system also contains a third Earth-sized planet candidate with an orbital period of 2.0 days that was previously identified as a likely planet with a low false-positive probability, but could not be firmly validated due to the lack of independent observations beyond TESS data. We combine two new transit observations from the 5.1m Hale Telescope at Palomar Observatory with archival TESS data and high-resolution imaging to statistically validate the planetary nature of TOI-2267 d ($0.98\pm0.09 R_{\oplus}$ if orbiting the primary star, or $1.77\pm0.43 R_{\oplus}$ if orbiting the secondary star) using the updated TRICERATOPS+ pipeline. We attempt to determine the host star for TOI-2267 d using transit shape stellar density analysis, but are unable to conclusively assign a host. Our validation of TOI-2267 d suggests that TOI-2267 is either the first known double transiting M dwarf binary system, or hosts three planets in an extremely compact orbital configuration. - oai:arXiv.org:2512.10007v1 + A second planetesimal collision in the Fomalhaut system + https://arxiv.org/abs/2512.15861 + arXiv:2512.15861v1 Announce Type: new +Abstract: The nearby star Fomalhaut is orbited by a compact source, Fomalhaut b, which has previously been interpreted as either a dust-enshrouded exoplanet or a dust cloud generated by the collision of two planetesimals. Such collisions are rarely observed but their debris can appear in direct imaging. We report Hubble Space Telescope observations that show the appearance in 2023 of a second point source around Fomalhaut, resembling the appearance of Fomalhaut b twenty years earlier. We interpret this additional source as a dust cloud produced by a recent impact between two planetesimals. The positions and motion of two impact-generated dust clouds over twenty years provide constraints on the collisional dynamics in the debris belt. + oai:arXiv.org:2512.15861v1 astro-ph.EP - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by-nc-nd/4.0/ - Michael Greklek-McKeon, Jonathan Gomez Barrientos, Heather A. Knutson, Sebasti\'an Z\'u\~niga-Fern\'andez, Francisco J. Pozuelos, Morgan Saidel, W. Garrett Levine, Renyu Hu, Fei Dai, Tansu Daylan, John P. Doty, David R. Rodriguez, Joseph D. Twicken, David W. Latham, Jon M. Jenkins, Richard P. Schwarz + 10.1126/science.adu6266 + P. Kalas et al., Science 10.1126/science.adu6266 (2025) + Paul Kalas, Jason J. Wang, Maxwell A. Millar-Blanchaer, Bin B. Ren, Mark C. Wyatt, Grant M. Kennedy, Maximilian Sommer, Thomas M. Esposito, Robert J. De Rosa, Michael Fitzgerald - The SPace-based InterFerometer Feasibility (SPIFF) Project: Enabling Future High-Resolution Astronomy Across the EM Spectrum - https://arxiv.org/abs/2512.10009 - arXiv:2512.10009v1 Announce Type: new -Abstract: A plethora of astronomical science cases can only be achieved with high angular resolution observations, and we can expect the number of these to grow as astronomers are constrained by the size limitations of single-aperture space telescopes, making space-based interferometry inevitable. However, the enabling technologies do not have flight heritage at the system level, and the concept remains immature to much of the community, meaning no direct-detection synthetic-aperture space-based interferometer has yet flown and an opportunity exists for the UK to take a world leading role. Here we propose the SPace-based InterFerometry Feasibility (SPIFF) Project as a program to address both issues simultaneously by: 1) completing a thorough survey of the science cases across the EM spectrum that would directly benefit from, or be impossible without, space-based interferometry; 2) down selecting key requirements via a Science Traceability Matrix mapping exercise; 3) host a workshop for the UK astronomical community to consolidate these findings; 4) build a technology demonstration mission to raise TRL and achieve flight heritage of critical technologies. Such a program positions the UK as the partner of choice for any future NASA or ESA space-based interferometry mission, allowing the UK to lead groundbreaking scientific discoveries, while also directly benefiting the UK industrial base by advancing domestic exportable technologies and building direct synergy with other UK space priorities. Indeed, the UK is uniquely positioned to lead in space-based interferometry, possessing a rare trifecta of domestic strengths: world-class expertise in ground-based interferometry and space-based instrumentation; commercial entities developing mission-critical technologies; and scientists whose research spans the full range of science cases that would benefit directly from space-based interferometry. - oai:arXiv.org:2512.10009v1 - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + The AIDA-TNG project: dark matter profiles and concentrations in alternative dark matter models + https://arxiv.org/abs/2512.15869 + arXiv:2512.15869v1 Announce Type: new +Abstract: In the standard Cold Dark Matter (CDM) scenario, the density profiles of dark matter haloes are well described by analytical models linking their concentration to halo mass. Alternative scenarios, such as warm dark matter (WDM) and self-interacting dark matter (SIDM), modify the inner structure of haloes and predict different profile shapes and central slopes. We employ the AIDA-TNG simulations to investigate how alternative dark matter physics and baryonic processes jointly shape the internal structure of haloes. Using dark-matter-only and full-physics runs, we measure the dark matter density profiles of haloes spanning six orders of magnitude in mass, from 10^9.5 Msun to 10^14.5 Msub, and characterise them with multiple analytical models. We provide the distribution of the best-fitting parameters, as well as the concentration-mass relation in WDM and SIDM. The Einasto profile well reproduces the inner flattening produced in WDM models, both in the collisionless and in the full-physics runs. In SIDM dark-matter-only runs, haloes are better described by explicitly cored profiles, with core sizes that depend on mass and on the self-interaction model. When baryons are included, the differences between CDM and SIDM decrease, and such large dark-matter cores no longer form because adiabatic contraction in the baryon-dominated region counteracts self-interactions. Nevertheless, the coupling between baryons and self-interactions induces a broader range of inner slopes, including cases that are steeper than CDM at Milky Way masses. Alternative dark matter physics thus leaves clear signatures in the inner halo structure, even if baryons significantly reshape these differences. Our results are useful for future studies that need to predict the properties of haloes in multiple dark matter models. + oai:arXiv.org:2512.15869v1 + astro-ph.CO + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Berke Vow Ricketti, Victoria Yankelevich, Chris Benson, Renske Smit, Sebastian Kamann, Ettore Pedretti, Sebastian Marino, Gerard van Belle, Stephen Eales, Chris Bee, Mark Wyatt, Matthew Smith, Tim D. Pearce, Emily Williams, Rebecca Harwin, David Pearson, Andy Vick, Giorgio Savini, Taro Matsuo, Hiroshi Matsuo, Locke Spencer, David T. Leisawitz + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Giulia Despali, Carlo Giocoli, Lauro Moscardini, Annalisa Pillepich, Mark Vogelsberger, Massimo Meneghetti - Formation of circumstellar material during double-white-dwarf mergers and the early excess emissions in Type Ia supernovae - https://arxiv.org/abs/2512.10014 - arXiv:2512.10014v1 Announce Type: new -Abstract: Early excess emission observed in Type Ia supernovae (SNe Ia) within $\sim1$ day of explosion provides a critical window into their progenitor systems. In the present study, we investigate formation of the circumstellar matter (CSM) in double white-dwarf (WD) mergers. We further study the interaction between the CSM and the SN ejecta. We first model the orbital evolution and super-Eddington mass transfer/ejection in the double WD systems. We then conduct hydrodynamical and light-curve (LC) simulations of the SN-CSM interaction, assuming a prompt SN Ia explosion in a context of the carbon-ignited violent merger (C-ignited VM). Our simulations show that at the moment of the merger, the binary system has the CSM distribution following $\rho_{\mathrm{CSM}}\simeq D(r/10^{14}\ \mathrm{cm})^{-3.5}\ (D\simeq 10^{-14}\text{--}10^{-13}\ \rm g\ cm^{-3})$. The simulated LCs reproduce the early flux excesses across optical to UV bands, as well as their color evolution, observed in the VM candidates, i.e., 03fg/02es-like SNe Ia. This supports that 03fg/02es-like objects originate from the VM explosions. We also discuss the case of the helium-ignited VM, which might be realized in some WD-WD mergers depending on the He content in the system. Focused here is the timing when the explosion is initiated, and we find that the explosion is initiated after the companion WD is, at least partially, tidally disrupted also in this case; we thus expect the formation of the CSM through the mass transfer phase also for the helium-ignited VM scenario. - oai:arXiv.org:2512.10014v1 - astro-ph.HE - astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + Dark Acoustic Oscillations as an Early-Universe Explanation of the DESI Anomaly + https://arxiv.org/abs/2512.15870 + arXiv:2512.15870v1 Announce Type: new +Abstract: DESI DR2 data have been widely interpreted as evidence for late-time evolving dark energy (DE) with an apparent phantom crossing. Here we investigate an alternative explanation, based on early-Universe physics. If dark acoustic oscillations (DAO) are close in scale to baryon acoustic oscillations (BAO), they can bias the extraction of the BAO scale from the peak in the galaxy correlation function. This leads to an apparent shift in the inferred distance if the superposition of BAO and DAO features is misinterpreted as being due to BAO only. Taking this shift into account, we find that a DAO with percent-level amplitude can reconcile DESI DR2 with Planck 2018 as well as Pantheon+ supernovae data, with fit improvement at a similar level as compared to evolving DE. Notably, a DAO feature with the required properties has been predicted in a previously proposed scenario that resolves the Hubble tension via a pre-recombination decoupling of dark matter and dark radiation (DRMD). The presence of a DAO feature close to the BAO peak can be scrutinized with future full-shape galaxy clustering data from DESI and Euclid. + oai:arXiv.org:2512.15870v1 + astro-ph.CO + hep-ph + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Yusuke Inoue, Keiichi Maeda, Takashi Nagao, Tatsuya Matsumoto + Mathias Garny, Florian Niedermann, Martin S. Sloth - Beyond prewhitening: detection of gravity modes and their period spacings in slowly pulsating B stars using the multitaper F-test - https://arxiv.org/abs/2512.10019 - arXiv:2512.10019v1 Announce Type: new -Abstract: Gravity modes in main-sequence stars have traditionally been studied using a prewhitening approach, which iteratively identifies modes in the Fourier domain and subsequently tunes their frequencies, amplitudes, and phases through time-domain regression. While effective, this method becomes inefficient when analysing large volumes of long time-series data and often relies on subjective stopping criteria to determine the number of iterations. We aim to perform frequency extraction of gravity modes in slowly pulsating B (SPB) stars using a statistically robust, data-driven approach based on advanced power spectrum and harmonic analysis techniques. Our approach employs the multitaper non-uniform fast Fourier transform, mtNUFFT, a power spectrum estimator that addresses several statistical limitations of traditional methods such as the Lomb-Scargle periodogram. We apply its extension, the multitaper F-test, to extract coherent gravity modes from 4-year Kepler light curves of SPB stars and to search for period spacing patterns among the extracted modes. The multitaper F-test enables fast and accurate extraction of the properties of gravity modes with quasi-infinite lifetimes, preferentially selecting modes that exhibit purely periodic behaviour. Although the method typically extracts fewer frequencies than conventional prewhitening, it recovers most known modes and, in some cases, reveals new ones. We also find evidence for gravity modes with long but finite lifetimes, and detect more than one period spacing pattern in some of the studied SPB stars. Overall, the multitaper F-test offers a more objective and statistically sound alternative to prewhitening. It scales efficiently to large datasets containing thousands of pulsators, and has the potential to facilitate mode identification and to distinguish between the different excitation mechanisms operating in SPB stars. - oai:arXiv.org:2512.10019v1 - astro-ph.SR - astro-ph.IM - stat.AP - Fri, 12 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Aarya A. Patil, Conny Aerts, Nikki Y. N. Wang, Jordan Van Beeck, May G. Pedersen - - - Classification of a New X-ray Catalog of Likely Counterparts to 4FGL-DR4 Unassociated Gamma-ray Sources Using a Neural Network - https://arxiv.org/abs/2512.10023 - arXiv:2512.10023v1 Announce Type: new -Abstract: Our survey of the fourth $\mathit{Fermi}$ Large Area Telescope catalog (4FGL) unassociated gamma-ray source regions using the X-Ray Telescope (XRT) and Ultraviolet/Optical Telescope (UVOT) aboard the Neil Gehrels $\mathit{Swift}$ Observatory ($\mathit{Swift}$) provides new XRT and UVOT source detections and localizations to help identify potential low-energy counterparts to unassociated $\mathit{Fermi}$ gamma-ray sources. We present a catalog of 218 singlet and 70 multiplet $\mathit{Swift}$ X-ray sources detected within the positional uncertainty ellipses of 244 unassociated $\mathit{Fermi}$ gamma-ray sources from the 4FGL-DR4 catalog, 144 of which are not previously cataloged by Kerby et al. (2021b). For each X-ray source, we derive its X-ray flux and photon index, then use simultaneous UVOT observations with optical survey data to estimate its $V$-band magnitude. We use these parameters as inputs for a multi-layer perceptron (MLP) neural network classifier (NNC) trained to classify sources as blazars, pulsars, or ambiguous gamma-ray sources. For the 213 singlet sources with X-ray and optical data, we classify 173 as likely blazars ($P_\mathrm{bzr} > 0.99$) and 6 as likely pulsars ($P_\mathrm{bzr} < 0.01$), with 34 sources yielding ambiguous results. Including 70 multiplet X-ray sources, we increase the number of $P_\mathrm{bzr} > 0.99$ to 227 and $P_\mathrm{bzr} < 0.01$ to 16. For the subset of these classifications that have been previously studied, a large majority agree with prior classifications, supporting the validity of using this NNC to classify the unknown and newly detected gamma-ray sources. - oai:arXiv.org:2512.10023v1 + In-plane Black-hole Spin Measurements Suggest Most Gravitational-wave Mergers Form in Triples + https://arxiv.org/abs/2512.15873 + arXiv:2512.15873v1 Announce Type: new +Abstract: The spin-orbit tilt angles $\theta_{1(2)}$ of merging stellar-mass black holes provide key insights into their astrophysical origin. The LIGO, Virgo, and KAGRA Collaborations (2025a, arXiv:2508.18083) report that the spin-orbit tilt distribution of mergers in the latest Gravitational-Wave Transient Catalog 4.0 exhibits a global peak at near-perpendicular directions $\cos\theta_{1(2)}\approx0$. Here, we recover this feature using hierarchical Bayesian inference with parametric models that are tailored to enhance the diagnostic power about astrophysical formation channels. We find that the spin distribution of the low-mass bulk of the binary black hole merger population $(m_1\lesssim 44.3^{+8.7}_{-4.6}\,\rm M_\odot)$ can be well-modelled by a dominant Gaussian component that peaks at $\cos\theta_{1(2)}\approx0$, possibly mixed with a subdominant isotropic component. Models that include a component with spins preferentially aligned with the orbit are disfavoured by current data (with Bayes factors $|\Delta\ln\mathcal{B}|\approx1$ to $3$) and constrain its contribution to be small ($\xi\sim\mathcal{O}(1)\,\%$). If these findings are reinforced by more detections, they would challenge any major contribution from the traditional isolated-binary formation scenario yielding closely aligned spins. Instead, the dominant component with near-perpendicular spins qualitatively matches expectations from the evolution of isolated massive stellar triples in the galactic field, where the Lidov-Kozai effect naturally produces a unique overabundance of mergers with $\cos\theta_{1(2)}\approx0$. + oai:arXiv.org:2512.15873v1 astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + gr-qc + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Kyle D. Neumann, Abraham D. Falcone, Stephen DiKerby, Sierra Deppe, Elizabeth C. Ferrara, Jamie A. Kennea, Brad Cenko, Eric Grove + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Jakob Stegmann, Fabio Antonini, Aleksandra Olejak, Sylvia Biscoveanu, Vivien Raymond, Stefano Rinaldi, Beth Flanagan - Stellar properties and chemical features of the Gaia Catalogue of Nearby Stars observed by GALAH DR4 - https://arxiv.org/abs/2512.10037 - arXiv:2512.10037v1 Announce Type: new -Abstract: The Gaia Catalogue of Nearby Stars (GCNS) comprises approximately 330 000 stars within 100 pc of the Sun, as observed by Gaia data release 3 (Gaia DR3). Meanwhile, the GALAH DR4 survey has spectroscopically characterised nearly one million stars, delivering detailed chemical abundances (up to 30 elements). We present a joint analysis of the $\sim$ 6 000 stars common to both catalogues, offering initial insights into the stellar and chemical properties of the solar neighborhood. Our preliminary results indicate that the majority of these stars are FGK main-sequence objects, with some A-type interlopers (with effective temperatures ranging between 3 000 and 8 000 K), with median ages of $\sim$ 1.6 Gyr (ranging from 0.10 to 14.79 Gyr), and metal-poorer when compared to the Sun: [Fe/H] $\approx$ -0.19 dex. Additionally, most of the stars are disc members, with some local halo (high-velocity) stars identified. Building on this foundation, future work will deeper exploit the full spectroscopic information and orbital parameters from value-added catalogues to refine Galactic component classifications (thin-thick disc versus halo membership), perform detailed chemical profiling, and deliver a comprehensive chemo-dynamical characterisation of the solar neighborhood. This will provide new insights into the formation and evolution of nearby stellar populations. - oai:arXiv.org:2512.10037v1 + Bright Long Secondary Period Stars for Follow-up Observations + https://arxiv.org/abs/2512.15874 + arXiv:2512.15874v1 Announce Type: new +Abstract: Long secondary period (LSP) variable stars are a subclass of long-period variables (LPV) that exhibit additional long-term variability alongside pulsations. Despite being observed in over 30% of LPVs, the reason behind the LSP phenomenon is still debated. The most favoured explanation, supported by recent growing evidence, is binarity, where the pulsating giant star has a substellar-mass companion. To further test this hypothesis, it is important to identify bright LSP variables, for which high-quality spectroscopic and interferometric observations can be obtained more easily. Motivated by the absence of a catalog of bright nearby LSPs, we searched the All Sky Automated Survey (ASAS) data in the $V$-band magnitude range 5.5-14 mag, and for declinations $< +28^\circ$. The resulting catalog contains 23 LSPs, 13 of which are new discoveries. We compare our catalog with the LSP lists available in the literature. + oai:arXiv.org:2512.15874v1 astro-ph.SR - astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Pedro Henrique Rocha de Andrade, Maria Luiza Linhares Dantas, Ana Cecilia Soja + http://creativecommons.org/licenses/by/4.0/ + P. Iwanek, D. M. Skowron, G. Pojma\'nski, I. Soszy\'nski - High-energy astrochemistry in the molecular interstellar medium - https://arxiv.org/abs/2512.10060 - arXiv:2512.10060v1 Announce Type: new -Abstract: In the past decade, there has been a significant shift in astrochemistry with a renewed focus on the role of non-thermal processes on the molecular interstellar medium, in particular energetic particles (such as cosmic ray particles and fast electrons) and X-ray radiation. This has been brought about in large part due to new observations of interstellar complex organic molecules (iCOMS) in environments that would inhibit their formation, such as cold, dense gas in prestellar cores or in the highly energetic environments in galactic centers. In parallel, there has been a plethora of new laboratory investigations on the role of high-energy radiation and electrons on the chemistry of astrophysical ices, demonstrating the ability of this radiation to induce complex chemistry. In recent years, theoretical models have also begun to include newer cosmic-ray-driven processes in both the gas and ice phases. In this review, we unify aspects of the chemistry driven by X-ray radiation and energetic particles into a ``high-energy astrochemistry'', defining this term and reviewing the underlying chemical processes. We conclude by examining various laboratories where high-energy astrochemistry is at play and identify future issues to be tackled. - oai:arXiv.org:2512.10060v1 + Shedding the envelope: JWST reveals a kiloparsec-scale [OIII]-weak Balmer shell around a z=7.64 quasar + https://arxiv.org/abs/2512.15881 + arXiv:2512.15881v1 Announce Type: new +Abstract: Luminous quasars at the redshift frontier z>7 serve as stringent probes of super-massive black hole formation and they are thought to undergo much of their growth obscured by dense gas and dust in their host galaxies. Fully characterizing the symbiotic evolution of SMBHs and hosts requires rest-frame optical observations that span spatial scales from the broad-line region to the ISM and CGM. JWST now provides the necessary spatially resolved spectroscopy to do so. But the physical conditions that regulate the interplay between SMBHs and their hosts at the highest redshifts, especially the nature of early feedback phases, remain unclear. We present JWST/NIRSpec IFU observations of J0313$-$1806 at z=7.64, the most distant luminous quasar known. + From the restframe optical spectrum of the unresolved quasar, we derive a black hole mass of $M_\mathrm{BH}=(1.63 \pm 0.10)\times10^9 M_\odot$ based on H$\beta$ and an Eddington rate of $\lambda=L/L_\mathrm{Edd}=0.80\pm 0.05$, consistent with previous MgII-based estimates. J0313-1806 exhibits no detectable [O III] emission on nuclear scales. Most remarkably, we detect an ionized gas shell extending out to $\sim 1.8$ kpc traced by H$\beta$ emission that also lacks any significant [O III], with a $3\sigma$ upper limit on the [O III]$ \lambda$5007 to H$\beta$ flux ratio of $\log_{10} \left( F(\mathrm{[OIII]})/F(\mathrm{H}\beta)\right)=-1.15$. + Through photoionization modelling, we demonstrate that the extended emission is consistent with a thin, clumpy outflowing shell where [OIII] is collisionally de-excited by dense gas. We interpret this structure as a fossil remnant of a recent blowout phase, providing evidence for episodic feedback cycles in one of the earliest quasars. These findings suggest that dense ISM phases may play a crucial role in shaping the spectral properties of quasars accross cosmic time. + oai:arXiv.org:2512.15881v1 astro-ph.GA - astro-ph.EP astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Brandt A. L. Gaches, Serena Viti - - - Hipparcos, Gaia, and RVs reveal that the radio emitting F star HD 220242 has an M dwarf companion, a likely source of the radio emission - https://arxiv.org/abs/2512.10072 - arXiv:2512.10072v1 Announce Type: new -Abstract: The detection of circularly polarized, low frequency radio emission offers the tantalizing possibility of the observation of interactions between stars and their possible substellar companions, as well as direct emission from exoplanets. Additional follow up of systems with radio emission is key to understanding the true origin of the emission, since multiple astrophysical mechanisms can plausibly lead to such signals. While nineteen M dwarfs were detected by LOFAR in circular polarization as part of the V-LoTSS survey, HD~220242 is the only F star to have a circularly polarized low frequency radio detection in the same survey. We conducted radial velocity follow up with the Habitable-zone Planet Finder and combined these observations with additional archival RVs and \textit{Hipparcos}-\textit{Gaia} proper motion accelerations to determine that HD~220242 has a stellar companion with P=16.79$\pm$0.04\,yrs and a mass of $0.619\pm0.014$\,M$_\odot$. We use Spectral Energy Distribution fitting and lack of any UV excess to rule out a co-evolved white dwarf companion and confirm that the companion is an M dwarf star. Given that F stars lack the coronal properties to produce such coherent emission, and the companion mass and lack of UV excess are consistent with an M dwarf, the radio emission is most plausibly associated with the companion. - oai:arXiv.org:2512.10072v1 - astro-ph.SR - astro-ph.EP - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Megan Delamer (Department of Astronomy and Astrophysics Pennsylvania State University, Center for Exoplanets and Habitable Worlds), Gu{\dh}mundur Stef\'ansson (Anton Pannekoek Institute for Astronomy University of Amsterdam), Suvrath Mahadevan (Department of Astronomy and Astrophysics Pennsylvania State University, Center for Exoplanets and Habitable Worlds), Caleb I. Ca\~nas (NASA Goddard Space Flight Center), Harish K. Vedantham (ASTRON Netherlands Institute for Radio Astronomy, Kapteyn Astronomical Institute University of Groninngen), Arvind F. Gupta (US National Science Foundation National Optical-Infrared Astronomy Research Laboratory), Joseph R. Callingham (ASTRON Netherlands Institute for Radio Astronomy, Anton Pannekoek Institute for Astronomy University of Amsterdam), Juan Bautista Climent Oliver (Departament d'Astronomia i Astrofisica Universitat de Valencia), William Cochran (McDonald Observatory, Center for Planetary Systems Habitability), Rachel B. Fernandes (Department of Astronomy and Astrophysics Pennsylvania State University, Center for Exoplanets and Habitable Worlds), Evan Fitzmaurice (Department of Astronomy and Astrophysics Pennsylvania State University, Center for Exoplanets and Habitable Worlds), Jose Carlos Guirado (Departament d'Astronomia i Astrofisica Universitat de Valencia, Observatori Astron\`omic Universitat de Val\`encia), Michael Hartmann (Th\"uringer Landessternwarte Tautenburg), Artie P. Hatzes (Th\"uringer Landessternwarte Tautenburg), Elise Koo (Anton Pannekoek Institute for Astronomy University of Amsterdam), Jessica E. Libby-Roberts (Department of Astronomy and Astrophysics Pennsylvania State University, Center for Exoplanets and Habitable Worlds), Joe P. Ninan (Department of Astronomy and Astrophysics Tata Institute of Fundamental Research), Miguel P\'erez-Torres (Instituto de Astrof\'isica de Andaluc\'ia, School of Sciences European University Cyprus), Paul Robertson (Department of Physics & Astronomy The University of California Irvine), Arpita Roy (Astrophysics & Space Institute Schmidt Sciences), Christian Schwab (School of Mathematical and Physical Sciences Macquarie University) + Julien Wolf, Eduardo Ba\~nados, Xiaohui Fan, Antoine Dumont, James E. Davies, David S. N. Rupke, Jinyi Yang, Weizhe Liu, Silvia Belladitta, Aaron Barth, Sarah Bosman, Tiago Costa, Frederick B. Davies, Roberto Decarli, Dominika \v{D}urov\v{c}\'ikov\'a, Anna-Christina Eilers, Hyunsung D. Jun, Yichen Liu, Federica Loiacono, Alessandro Lupi, Chiara Mazzucchelli, Maria Pudoka, Sof\'ia Rojas-Ruiz, Jan-Torge Schindler, Wei Leong Tee, Benny Trakhtenbrot, Fabian Walter, Huanian Zhang - The AURORA Survey: Constraining Chemical Enrichment Pathways at Cosmic Noon with Argon Abundances - https://arxiv.org/abs/2512.10130 - arXiv:2512.10130v1 Announce Type: new -Abstract: We present argon abundances from a sample of 46 star-forming galaxies at $z=2-3.5$ from the Assembly of Ultradeep Rest-Optical Observations Revealing Astrophysics (AURORA) program. Although argon is an $\alpha-$element produced by Core Collapse Supernovae (CCSNe), the latest supernova yield models suggest additional argon production and enrichment by Type Ia supernovae (SNe Ia), unlike other $\alpha-$elements such as oxygen. To study the relationship between argon and oxygen abundances, we construct two median-stacked composite spectra for separate $z=2.0-2.6$ and $z=2.8-3.5$ redshift bins, presenting more representative measurements than previous samples that require individual detection of faint lines. Abundance ratios were determined using an empirical calibration based on the strength of the [ArIII]$\lambda7137$ emission line relative to the [OIII]$\lambda5008$ emission line. With this calibration, we estimate argon abundances (Ar/O) of $0.42^{+0.12}_{-0.10}\mbox{(Ar/O)}_{\odot}$ for the $\langle z \rangle = 2.26$ bin and $0.42^{+0.12}_{-0.11}\mbox{(Ar/O)}_{\odot}$ for the $\langle z \rangle = 3.15$ bin, suggesting minimal SNe Ia and dominant CCSNe enrichment in this sample. Comparison of our abundance measurements of $z\sim 2-3$ AURORA galaxies with chemical evolution modeling of Milky Way stars shows consistency with the Milky Way Bulge component, suggesting a rapid star-formation timescale. However, even larger samples of actively star-forming galaxies with available argon abundances, as well as comparisons between argon abundance and other critical galaxy properties (e.g., sSFR) and models (e.g., one tuned specifically to this redshift range) are needed to draw stronger conclusions on the role of argon in galactic chemical enrichment at Cosmic Noon. - oai:arXiv.org:2512.10130v1 + The AIDA-TNG project: abundance, radial distribution, and clustering properties of halos in alternative dark matter models + https://arxiv.org/abs/2512.15883 + arXiv:2512.15883v1 Announce Type: new +Abstract: Warm and self-interactive dark matter cosmologies have been proposed as non-baryonic solutions to the tensions between the $\Lambda$ Cold Dark Matter model and observations at the kpc scale. In this paper, we use the dark matter-only runs of the \textsc{aida-tng} project, a set of cosmological simulations of different sizes and resolutions, to analyze the macroscopic impact of alternative dark matter models on the abundance, the radial distribution and the clustering properties of halos. We adopt the halo occupation distribution formalism to characterize the evolution of its parameters $M_1$ and $\alpha$ with the mass and redshift selection of our sample. By dividing the halo population into central and satellites, we are able to study their spatial density profile, finding that a Navarro-Frenk-White model is not accurate enough to describe the radial distribution of subhalos, and that a generalized Navarro-Frenk-White model is required instead. Warm dark matter models, in particular, present a cuspier distribution of satellites, whereas self-interacting dark matter exhibits a shallower density profile. Moreover, we find that the small-scale clustering of dark matter halos provides a powerful tool to discriminate between alternative dark matter scenarios, in preparation for a more detailed study that fully incorporates baryonic effects, and for a comparison with observational data from galaxy clustering. + oai:arXiv.org:2512.15883v1 + astro-ph.CO astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jack Foley, Alice Shapley, Ryan Sanders, Naveen A. Reddy, Michael W. Topping, Thomas M. Stanton, Max Pettini, Fergus Cullen, Richard S. Ellis, N. M. F\"orster Schreiber, Tucker Jones, Anthony J. Pahl, Leonardo Clarke, Natalie Lam + Massimiliano Romanello, Giulia Despali, Federico Marulli, Carlo Giocoli, Lauro Moscardini - Deuterium fractionation and CO depletion in Barnard 5 - https://arxiv.org/abs/2512.10143 - arXiv:2512.10143v1 Announce Type: new -Abstract: Deuterium fractionation provides a key diagnostic of the physical and chemical evolution of prestellar and protostellar cores, where it is strongly linked to CO depletion in cold, dense gas. We present the first spatially resolved maps of deuterium fraction and CO depletion in the Barnard 5 (B5) region of the Perseus molecular cloud, covering both a starless core and the protostellar core hosting the Class 0/I source IRAS 03445+3242. Using IRAM 30~m observations of N$_2$H$^+$(1--0), N$_2$D$^+$(1--0), H$^{13}$CO$^+$(1--0), and DCO$^+$(2--1), complemented by C$^{18}$O(2--1) data, we derive column density, deuterium fraction, and CO depletion maps. We find that the deuterium fraction in both mentioned nitrogen- and carbon-bearing species increases from the protostellar to the starless core, reaching $R_D^{\rm N_2H^+}=0.43\pm0.10$ and $R_D^{\rm HCO^+}=0.09\pm0.02$ in the starless core, compared with $0.15\pm0.03$ and $0.05\pm0.01$, respectively, in the protostellar core. The CO depletion factor also rises from $4.1\pm0.1$ to $5.0\pm0.1$ across the same transition. While the embedded YSO reduces deuteration in the dense inner gas, the less dense envelope traced by HCO$^+$ is only slightly affected at our resolution. Our analysis confirms that CO freeze-out and the presence of a protostar jointly regulate deuterium chemistry in star-forming regions. - oai:arXiv.org:2512.10143v1 + Cored galaxies in cuspy dark matter halos + https://arxiv.org/abs/2512.15886 + arXiv:2512.15886v1 Announce Type: new +Abstract: We investigate constraints on the inner stellar density profile from photometric data of dwarf spheroidal and ultra-faint dwarf galaxies. Our aim is to clarify under what conditions cored stellar profiles require dark matter halos that are also cored, deviating from the cuspy profiles expected for cold dark matter halos. We consider a variety of spherically symmetric stellar profiles, which we classify as "strong" or "weak" cores and cusps according to the behavior of the slope ($b_0$) and logarithmic slope ($\gamma_0$) at their centers. We explore which profiles lead to unphysical negative distribution functions when embedded in a cuspy halo, treating isotropic and anisotropic kinematics separately. We find that weakly-cored stellar profiles in 3D (i.e., $b_0 \neq 0$, $\gamma_0=0$) can be consistent with cuspy dark matter profiles, but strong 3D cores ($b_0=\gamma_0=0$) are not. However, both weak and strong 3D cores yield nearly indistinguishable inner profiles in projection, which implies that ruling out a dark matter cusp from photometric data alone is highly challenging. As an example, we study the profiles of ultra-faint dwarf galaxies and find that they are consistent with both weak and strong 3D cores. This is not just a result of the limited numbers of stars in these systems, since we reach the same conclusion even for Fornax, one of the most luminous and best-studied dwarf spheroidal companions of the Milky Way. We conclude that, based on current data and analysis techniques, cored surface density profiles in nearby dwarf galaxies cannot be taken as strong evidence against the presence of cuspy dark matter halos. + oai:arXiv.org:2512.15886v1 astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Igor Petrashkevich, Anna Punanova, Paola Caselli, Jaime E. Pineda, Olli Sipila, Anton I. Vasyunin + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Fernando Valenciano, Jorge Martin Camalich, Arianna Di Cintio, Julio F. Navarro, Giuseppina Battaglia, Rapha\"el Errani, Justin I. Read - Discovery of Weak O VI Absorption in Underdense Regions of the Low-Redshift Intergalactic Medium - https://arxiv.org/abs/2512.10163 - arXiv:2512.10163v1 Announce Type: new -Abstract: We search for weak O VI absorption in the low-redshift intergalactic medium (IGM) using 82 high signal-to-noise quasar spectra obtained with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. From this dataset, we compile a clean sample of 396 intervening Lyman-alpha (Lya) absorption lines with H I column densities log (N_HI) < 14.5, all of which lack individual O VI absorption with log (N_OVI ) > 13. We perform a spectral stacking analysis at the expected location of the O VI doublet, revealing O VI absorption with a statistical significance greater than 5$\sigma$, and measure an equivalent width of 1.7 $\pm$ 0.3 mA, corresponding to log (N_OVI ) = 12.14 $\pm$ 0.08. The stacked O VI absorption signal associated with strong Lya absorbers (13.5 <= log N_HI < 14.5) is significantly stronger than that associated with weaker Lya absorbers (12.5 <= log N_HI < 13.5). For the subset of 81 broad Lya absorbers (BLAs; b(HI) > 45 km/s), we obtain a marginal $\sim$3 $\sigma$ O VI detection. Other than Si III, detected at 5$\sigma$, no associated metal lines are found. Cross-correlation of the Lya absorbers with galaxies indicates that 93% of these absorbers are not associated with bright galaxies within 1 Mpc, implying that the detected O VI originates in the diffuse IGM rather than the circumgalactic medium. The stacked O VI signal suggests characteristic metallicities of $\sim 0.01\,Z_{\odot}$ under photoionisation and $\sim 0.001\,Z_{\odot}$ under collisional ionisation conditions, though these estimates are model-dependent and assume that O VI and H I trace the same phase. This study provides the first observational evidence for metal absorption in low-column-density Lya systems that individually exhibit no detectable metals, placing important constraints on the metal enrichment of the underdense IGM. - oai:arXiv.org:2512.10163v1 + Observational constraints on the origin of the elements. X. Combining NLTE and machine learning for chemical diagnostics of 4 million stars in the 4MIDABLE-HR survey + https://arxiv.org/abs/2512.15888 + arXiv:2512.15888v1 Announce Type: new +Abstract: We present 4MOST-HR resolution Non-Local Thermal Equilibrium (NLTE) Payne artificial neural network (ANN), trained on 404,793 new FGK spectra with 16 elements computed in NLTE. This network will be part of the Stellar Abundances and atmospheric Parameters Pipeline (SAPP), which will analyse 4 million stars during the five year long 4MOST consortium 4: MIlky way Disc And BuLgE High-Resolution (4MIDABLE-HR) survey. A fitting algorithm using this ANN is also presented that is able to fully-automatically and self-consistently derive both stellar parameters and elemental abundances. The ANN is validated by fitting 121 observed spectra of low-mass FGKM type stars, including main-sequence dwarf, subgiant and giant stars down to [Fe/H] $\approx -3.4$ degraded to 4MOST-HR resolution, and comparing the derived abundances with the output of the classical radiative transfer code TSFitPy. We are able to recover all 18 elemental abundances with a bias <0.13 and spread <0.16 dex, although the typical values are <0.09 dex for most elements. These abundances are compared to the OMEGA+ Galactic Chemical Evolution model, showcasing for the first time, the expected performance and results obtained from high-resolution spectra of the quality expected to be obtained with 4MOST. The expected Galactic trends are recovered, and we highlight the potential of using many chemical elements to constrain the formation history of the Galaxy. + oai:arXiv.org:2512.15888v1 + astro-ph.SR astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Sapna Mishra, Vikram Khaire, Romeo Pallikkara, Anand Narayanan, Andrew J. Fox + Nicholas Storm, Maria Bergemann, Tomasz R\'o\.za\'nski, Victor F. Ksoll, Thomas Bensby, Guillaume Guiglion, Gra\v{z}ina Tautvai\v{s}ien\.e - Strong Bars, Strong Inflow: The Effect of Bar Strength on Gas Inflow - https://arxiv.org/abs/2512.10164 - arXiv:2512.10164v1 Announce Type: new -Abstract: Stellar bars are elongated structures in disk galaxies that can torque and funnel gas inward, influencing galaxy evolution. While strong bars are known to induce rapid inflow, the impact of weaker bars remains less certain. We collected spectroscopic data using the Isaac Newton Telescope to analyze 18 nearby galaxies (strongly barred, weakly barred, and unbarred) drawn from Galaxy Zoo DESI. We obtained spatial profiles of equivalent width (EW) and ionized gas velocity dispersion by fitting Gaussian profiles to the H{\alpha} emission line. Strongly barred galaxies exhibit a distinctive three-peaked EW[H{\alpha}] structure, consistent with inward funneling of gas. Weakly barred systems lack this pattern, which suggests limited inflow. Velocity dispersion distributions further distinguish the bar types, with strongly barred galaxies showing significantly higher values than weakly barred and unbarred systems. These results suggest that strong bars drive gas inflow, while weak bars exert a limited dynamical influence. - oai:arXiv.org:2512.10164v1 + The Next Generation Fornax Survey (NGFS).VIII. A Support Vector Machine Approach for Disentangling Globular Clusters from other Sources + https://arxiv.org/abs/2512.15895 + arXiv:2512.15895v1 Announce Type: new +Abstract: Wide-field, multi-band surveys now detect millions of unresolved sources in nearby galaxy clusters, yet separating globular clusters (GCs) from foreground stars and background galaxies remains challenging. Scalable, automated classification is therefore essential to convert the forthcoming data from facilities such as the Vera C. Rubin/LSST, the Roman and Euclid into robust constraints on galaxy assembly. We introduce a supervised classification method to separate GCs, stars, and galaxies based on their locations in color-color diagrams. The main objective is to recover a clean GC sample for future scientific analysis. The method exploits broad spectral energy distribution coverage, deep photometry, and is optimized for next-generation survey volumes. We use the central 3deg2 of the Next Generation Fornax Survey (NGFS), which images the Fornax cluster in u'g'i'JKs. We build a Support Vector Machine (SVM; svm.SVC, scikit-learn) using 15 features: all color combinations and basic morphological parameters. Spectroscopically confirmed sources define the training classes. Color pairs connecting near-UV/optical/near-IR. The full 15 feature model achieves 97.3% accuracy and a pruned 7 feature model built from the most informative, least correlated features achieves 96.6% accuracy. Misclassifications amount 8.4% and 10.4%, respectively. Omitting the u' or/and near-IR bands degrades performance. Emulating LSST filters with NGFS u'g'i' and DES r'z'Y shows that u' and Y bands are crucial, but models lacking NIR remain suboptimal. Combining broad SED coverage with simple morphological parameters enables precise, scalable separation of unresolved sources. Including NIR bands significantly improves GC classification, and joining LSST with forthcoming Euclid and Roman data will further enhance machine-learning frameworks. + oai:arXiv.org:2512.15895v1 astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Maelle Magnan, Tobias Geron, Izzy L. Garland, Chris J. Lintott, Jason Shingirai Makechemu, David O Ryan, Brooke D. Simmons, Rebecca J. Smethurst + http://creativecommons.org/licenses/by-sa/4.0/ + Yasna Ordenes-Brice\~no, Thomas H. Puzia, Paul Eigenthaler, Matias Bla\~na, Juan P. Carvajal, Matthew A. Taylor, Bryan W. Miller, Rohan Rahatgaonkar, Evelyn J. Johnston, Prasanta K. Nayak, Gaspar Galaz - Spectrally Resolved Gas Kinematics in Cygnus A: XRISM Detects AGN Jet-induced Velocity Dispersion in Multi-temperature Gas - https://arxiv.org/abs/2512.10167 - arXiv:2512.10167v1 Announce Type: new -Abstract: We report spectral analysis on a 170 ks XRISM \textit{Resolve} exposure of the core of Cygnus A. Analyzing the full field of view spectrum in the $1.7-12.0$ keV band, we find evidence for two-temperature cluster gas. The hotter ($kT = 5.53 \pm 0.13$ keV) gas has a velocity dispersion of $261 \pm 13$ km s$^{-1}$ and a bulk velocity of $120 \pm 20$ km s$^{-1}$ with respect to the central galaxy. The cooler gas ($kT = 2.0^{+0.4}_{-0.3}$ keV) has an even broader velocity dispersion of $440 \pm 130$ km s$^{-1}$, with a systematic uncertainty of $120$ km s$^{-1}$. The relative line-of-sight velocity between the hotter and cooler gas can be as high as $450 \pm 140$ km s$^{-1}$. We interpret the high velocity dispersions as a combination of turbulence and bulk motion due to the cocoon shock. The upper limit on the non-thermal pressure fraction for the hotter gas is $7.7 \pm 0.7\%$. We associate the cooler gas with the central region ($<35$ kpc) and the hotter phase with the gas surrounding it ($35-100$ kpc). The total energy due to the kinetic motion is $5.1 \times 10^{60}$ erg, consistent with the energy associated with the central radio source. The kinetic energy injection rate is $6.9 \times 10^{44}-7.4 \times 10^{45}$ erg s$^{-1}$ under varying assumptions of injection timescales. The range of injection power is higher than the cooling luminosity, and thus the heating and cooling rates in Cygnus A are unbalanced. - oai:arXiv.org:2512.10167v1 - astro-ph.HE - astro-ph.CO + Dust evolution across cosmic times as seen through DUSTY-GAEA + https://arxiv.org/abs/2512.15902 + arXiv:2512.15902v1 Announce Type: new +Abstract: For many decades, dust has been recognised as an important ingredient in galaxy formation and evolution. This paper presents a novel self-consistent implementation of dust formation by stars, destruction by supernova shocks and hot gas, and growth within the dense interstellar medium (ISM) in the GAEA state-of-the-art galaxy formation model. Our new model, DUSTY-GAEA, reproduces well the dust buildup as a function of stellar mass out to z $\sim$ 6, the scaling relations between the dust-to-gas/dust-to-metal ratios and stellar mass/metallicty in the local Universe, and the dust mass function in the local Universe and out to z $\sim$ 1. In the framework of our model, dust growth dominates the cosmic dust budget out to z $\sim$ 8, and we find that observational constraints beyond the local Universe can be reproduced only assuming such efficient dust growth in the dense ISM. Yet, reproducing the estimated number densities of dust-rich galaxies at higher redshifts remains challenging, as found also in independent theoretical work. We discuss our model predictions in comparison with both observational data and independent theoretical efforts, and highlight how further observational constraints at high redshifts would help constrain dust models. + oai:arXiv.org:2512.15902v1 astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Anwesh Majumder, T. Heckman, J. Meunier, A. Simionescu, B. R. McNamara, L. Gu, A. Ptak, E. Hodges-Kluck, M. Yukita, M. W. Wise, N. Roy + Omima Osman, Gabriella De Lucia, Fabio Fontanot, Lizhi Xie, Michaela Hirschmann - The Narrow Emission Lines of Seyfert 1 Galaxies: Comparisons with a Large SDSS Sample - https://arxiv.org/abs/2512.10186 - arXiv:2512.10186v1 Announce Type: new -Abstract: We analyzed a large sample of SDSS spectra of Seyfert galaxies, subdividing Seyfert 1s based on their narrow-to-broad Halpha components. Comparing their narrow-lines (NL) to Seyfert2s in line-ratio diagrams, most of the NL of strong Sy 1.0 and Sy 1.2s (with dominant broad lines) are the same as those of pure Sy2s. In contrast, only 25-30 percent of the Sy1.8 and Sy1.9 nuclei (with weak broad lines) are located in the pure Sy2 region, with the rest falling in the composite-star-forming region. We explain these Seyfert-plus-star-formation spectra with a simple model. It shows that 85 percent of NL in Sy1.9 are from HII-regions, while 88 percent of the NL in Sy 1.0 arise from the same NLR as in pure Sy2. About 6 percent of the strong and weak Sy1's have NL dominated by LINER emission, while 15 percent of intermediate Seyferts (Sy 1.5 and Sy 1.6) do. To confirm this Seyfert 1 AGN plus star formation combination, we used stellar absorption-lines to compare their stellar populations. Their Hdelta strengths show that LINERs, pure Sy2s, and also the broad-line dominated Sy1s have old stellar populations. The weak Sy 1s show stronger Hdelta absorption, indicating larger proportions of young stars. About one third of the u band light in Sy1.0 and 1.2 is blended Balmer lines and continuum from the BLR. The NL gas reddening increases as the BLR strength decreases, from Sy1.0 (0.13 mag), to Sy1.9 (0.40 mag), to Sy2s and LINERs both with 0.50 mag. Our data do not support the simplest version of Seyfert 1 and 2 unification, where both AGN classes have identical NL. - oai:arXiv.org:2512.10186v1 + Binarity Beyond Gaia: The case for a dedicated spectroscopic survey of binary stars + https://arxiv.org/abs/2512.15904 + arXiv:2512.15904v1 Announce Type: new +Abstract: Stellar multiplicity is a fundamental ingredient of stellar astrophysics, yet binary statistics across the Galaxy remain poorly constrained. The \emph{Gaia} mission has revolutionised binary star astrophysics by delivering high-precision astrometry, photometry and global radial velocities, and by providing hundreds of thousands of non-single-star solutions in DR3. However, the RVS magnitude limit, mission time span and scanning law impose strong selection effects in period, mass ratio, inclination and semi-amplitude, leaving large regions of the binary parameter space either sparsely sampled or effectively inaccessible. In this white paper we outline the case for a dedicated, wide-field, multi-epoch spectroscopic survey explicitly optimised for binary science: deeper than the \emph{Gaia} RVS limit, with flexible cadence from hours to years, and with moderate to high spectral resolution. Using a simplified forward model of \emph{Gaia} DR5-like performance, we highlight the populations for which robust orbital solutions will be rare (ultra short period, very long period, low-amplitude and compact-object binaries), and show how a ``Binarity Beyond \emph{Gaia}'' survey would fill these gaps. Such a programme would deliver a bias correctable census of stellar multiplicity across the Milky Way and provide the spectroscopic backbone needed to exploit binary samples from \emph{Rubin}/LSST, \emph{Roman} and \emph{LISA}. + oai:arXiv.org:2512.15904v1 + astro-ph.IM astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Matthew Malkan, Lisbeth Jensen, Lei Hao + Borja Anguiano (CEFCA) - Galaxy Phase-Space and Field-Level Cosmology: The Strength of Semi-Analytic Models - https://arxiv.org/abs/2512.10222 - arXiv:2512.10222v1 Announce Type: new -Abstract: Semi-analytic models are a widely used approach to simulate galaxy properties within a cosmological framework, relying on simplified yet physically motivated prescriptions. They have also proven to be an efficient alternative for generating accurate galaxy catalogs, offering a faster and less computationally expensive option compared to full hydrodynamical simulations. In this paper, we demonstrate that using only galaxy $3$D positions and radial velocities, we can train a graph neural network coupled to a moment neural network to obtain a robust machine learning based model capable of estimating the matter density parameters, $\Omega_{\rm m}$, with a precision of approximately 10%. The network is trained on ($25 h^{-1}$Mpc)$^3$ volumes of galaxy catalogs from L-Galaxies and can successfully extrapolate its predictions to other semi-analytic models (GAEA, SC-SAM, and Shark) and, more remarkably, to hydrodynamical simulations (Astrid, SIMBA, IllustrisTNG, and SWIFT-EAGLE). Our results show that the network is robust to variations in astrophysical and subgrid physics, cosmological and astrophysical parameters, and the different halo-profile treatments used across simulations. This suggests that the physical relationships encoded in the phase-space of semi-analytic models are largely independent of their specific physical prescriptions, reinforcing their potential as tools for the generation of realistic mock catalogs for cosmological parameter inference. - oai:arXiv.org:2512.10222v1 - astro-ph.CO + The Era of Binary Supermassive Black Holes: Coordination of Nanohertz-Frequency Gravitational-Wave Follow-up + https://arxiv.org/abs/2512.15911 + arXiv:2512.15911v1 Announce Type: new +Abstract: Here we summarize discussions and conclusions from the conference ``The Era of Binary Supermassive Black Holes: Coordination of Nanohertz-Frequency Gravitational-Wave Follow-up,'' held at the Aspen Center for Physics from February 2-7, 2025. The meeting facilitated a crucial knowledge exchange between electromagnetic and gravitational-wave theorists, observers, and cyber-infrastructure experts. The central goal was to guide the development of multi-messenger follow-up strategies for binary supermassive black hole detections by pulsar timing arrays. To build a common basis of understanding for the broader scientific community, this summary outlines the main considerations and recommendations from the meeting, summarizes the knowledge gaps identified, and ends with a potential roadmap to catalyze discussion about the search for electromagnetic counterparts to massive black hole binaries detected by pulsar timing arrays. + oai:arXiv.org:2512.15911v1 astro-ph.GA - cs.LG - Fri, 12 Dec 2025 00:00:00 -0500 + gr-qc + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Natal\'i S. M. de Santi, Francisco Villaescusa-Navarro, Pablo Araya-Araya, Gabriella De Lucia, Fabio Fontanot, Lucia A. Perez, Manuel Arn\'es-Curto, Violeta Gonzalez-Perez, \'Angel Chandro-G\'omez, Rachel S. Somerville, Tiago Castro + Sarah Burke-Spolaor, Tamara Bogdanovi\'c, Daniel J. D'Orazio, Michael Eracleous, Suvi Gezari, Matthew J. Graham, Kayhan G\"ultekin, Jeffrey Hazboun, Chiara M. F. Mingarelli, Gautham Narayan, Polina Petrov, Nicolo Veronesi - FEADME: Fast Elliptical Accretion Disk Modeling Engine - https://arxiv.org/abs/2512.10228 - arXiv:2512.10228v1 Announce Type: new -Abstract: We present FEADME (Fast Elliptical Accretion Disk Modeling Engine), a GPU-accelerated Python framework for modeling broad Balmer-line emission using a relativistic elliptical accretion-disk formalism. Leveraging Jax and NumPyro for differentiable forward modeling and efficient Bayesian inference, FEADME enables large-sample, reproducible analyses of disk-dominated emission-line profiles. We apply the framework to 237 double-peaked emitters (DPEs) from the literature and to five tidal disruption events (TDEs) with disk-like H$\alpha$ emission, fitting three physically motivated model families per spectrum and selecting the preferred model using approximate leave-one-out (LOO) cross-validation. We find that AGN exhibit a broad, continuous distribution of disk geometries and kinematics, with significant diversity in disk parameters. Most TDE disk parameter distributions are statistically indistinguishable from those of the AGN, with the sole robust difference being that TDE disks are significantly more circular, consistent with rapid debris circularization in tidal disruption events. The majority of both AGN and TDEs favor models that include both a disk and an additional broad-line component, suggesting that disk emission commonly coexists with more isotropic or wind-driven gas. These results indicate that once a line-emitting disk forms, its spectroscopic appearance is governed by similar physical processes in both persistent AGN and transient TDE accretion flows, and they demonstrate the utility of FEADME for population-level studies of disk structure in galactic nuclei. - oai:arXiv.org:2512.10228v1 + 2D or not 2D? Exploring 3D relativistic magnetic reconnection dynamics with highly accurate numerical simulations + https://arxiv.org/abs/2512.15954 + arXiv:2512.15954v1 Announce Type: new +Abstract: Fast reconnection in magnetically dominated plasmas is widely invoked in models of dissipation in pulsar winds, gamma-ray flares in the Crab nebula, and to explain the radio nanoshots of pulsars. When current sheets evolve reaching a critical inverse aspect ratio, scaling as $S^{-1/3}$ with the plasma Lundquist number, the so-called \textit{ideal} tearing instability sets in, with modes growing, independently of $S$, extremely rapidly on timescales of only a few light-crossing times of the sheet length. We present the first set of fully 3D simulations of current-sheet disruption triggered by the ideal tearing instability within the resistive relativistic MHD approximation, as appropriate in situations where the Alfv\'en velocity approaches the speed of light. We compare 3D setups with different initial conditions with their 2D counterparts, and we assess the impact of dimensionality and of the magnetic field topology on the onset, evolution, and efficiency of reconnection. In force-free configurations, 3D runs develop ideal tearing, secondary instabilities, and a thick, turbulent current layer, sustaining dissipation of magnetic energy longer than in 2D. In pressure-balanced current sheets with a null guide field, 2D reference runs show the familiar reconnection dynamics, whereas in 3D tearing dynamics is quenched after the linear phase, as pressure-driven modes growing on forming plasmoids outcompete plasmoid coalescence and suppress fast dissipation of magnetic energy. Taken together, these results suggest that the evolution and efficiency of reconnection depend sensitively on the local plasma conditions and current-sheet configuration, and can be properly captured only in fully 3D simulations. + oai:arXiv.org:2512.15954v1 astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Nicholas Earl, K. Decker French, Jason T. Hinkle, Yashasvi Moon, Margaret Shepherd, Margaret E. Verrico + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Vittoria Berta, Matteo Bugli, Andrea Mignone, Giancarlo Mattia, Luca Del Zanna, Stefano Truzzi - EP250827b/SN 2025wkm: An X-ray Flash-Supernova Powered by a Central Engine and Circumstellar Interaction - https://arxiv.org/abs/2512.10239 - arXiv:2512.10239v1 Announce Type: new -Abstract: We present the discovery of EP250827b/SN 2025wkm, an X-ray Flash (XRF) discovered by the Einstein Probe (EP), accompanied by a broad-line Type Ic supernova (SN Ic-BL) at $z = 0.1194$. EP250827b possesses a prompt X-ray luminosity of $\sim 10^{45} \, \rm{erg \, s^{-1}}$, lasts over 1000 seconds, and has a peak energy $E_{\rm{p}} < 1.5$ keV at 90% confidence. SN 2025wkm possesses a double-peaked light curve (LC), though its bolometric luminosity plateaus after its initial peak for $\sim 20$ days, giving evidence that a central engine is injecting additional energy into the explosion. Its spectrum transitions from a blue to red continuum with clear blueshifted Fe II and Si II broad absorption features, allowing for a SN Ic-BL classification. We do not detect any transient radio emission and rule out the existence of an on-axis, energetic jet $\gtrsim 10^{50}~$erg. In the model we invoke, the collapse gives rise to a long-lived magnetar, potentially surrounded by an accretion disk. Magnetically-driven winds from the magnetar and the disk mix together, and break out with a velocity $\sim 0.35c$ from an extended circumstellar medium with radius $\sim 10^{13}$ cm, generating X-ray breakout emission through free-free processes. The disk outflows and magnetar winds power blackbody emission as they cool, producing the first peak in the SN LC. The spin-down luminosity of the magnetar in combination with the radioactive decay of $^{56}$Ni produces the late-time SN LC. We end by discussing the landscape of XRF-SNe within the context of EP's recent discoveries. - oai:arXiv.org:2512.10239v1 - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + DESI-DR1 $3 \times 2$-pt analysis: consistent cosmology across weak lensing surveys + https://arxiv.org/abs/2512.15960 + arXiv:2512.15960v1 Announce Type: new +Abstract: We present a joint cosmological analysis of projected galaxy clustering observations from the Dark Energy Spectroscopic Instrument Data Release 1 (DESI-DR1), and overlapping weak gravitational lensing observations from three datasets: the Kilo-Degree Survey (KiDS-1000), the Dark Energy Survey (DES-Y3), and the Hyper-Suprime-Cam Survey (HSC-Y3). This combination of large-scale structure probes allows us to measure a set of $3 \times 2$-pt correlation functions, breaking the degeneracies between parameters in cosmological fits to individual observables. We obtain mutually-consistent constraints on the parameter $S_8 = \sigma_8 \sqrt{\Omega_{\rm m}/0.3} = 0.786^{+0.022}_{-0.019}$ from the combination of DESI-DR1 and DES-Y3, $S_8 = 0.760^{+0.020}_{-0.018}$ from KiDS-1000, and $S_8 = 0.771^{+0.026}_{-0.027}$ from HSC-Y3. These parameter determinations are consistent with fits to the Planck Cosmic Microwave Background dataset, albeit with $1.5-2\sigma$ lower values in the $S_8-\Omega_{\rm m}$ plane. We perform our analysis with a unified pipeline tailored to the requirements of each cosmic shear survey, which self-consistently determines cosmological and astrophysical parameters. We generate an analytical covariance matrix for the correlation data including all cross-covariances between probes, and we design a new blinding procedure to safeguard our analysis against confirmation bias, whilst leaving goodness-of-fit statistics unchanged. Our study is part of a suite of papers that present joint cosmological analyses of DESI-DR1 and weak gravitational lensing datasets. + oai:arXiv.org:2512.15960v1 + astro-ph.CO + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Gokul P. Srinivasaragavan, Dongyue Li, Xander J. Hall, Ore Gottlieb, Genevieve Schroeder, Heyang Liu, Brendan O'Connor, Chichuan Jin, Mansi Kasliwal, Tom\'as Ahumada, Qinyu Wu, Christopher L. Fryer, Annabelle E. Niblett, Dong Xu, Maria Edvige Ravasio, Grace Daja, Wenxiong Li, Shreya Anand, Anna Y. Q. Ho, Hui Sun, Daniel A. Perley, Lin Yan, Eric Burns, S. Bradley Cenko, Jesper Sollerman, Nikhil Sarin, Anthony L. Piro, Amar Aryan, M. Coleman Miller, Jie An, Tao An, Moira Andrews, Jule Augustin, Eric C. Bellm, Aleksandra Bochenek, Malte Busmann, Krittapas Chanchaiworawit, Huaqing Chen, Alberto J. Castro-Tirado, Ali Esamdin, Jennifer Faba-Moreno, Joseph Farah, Shaoyu Fu, Johan P. U. Fynbo, Julius Gassert, Estefania Padilla Gonzalez, Matthew Graham, Daniel Gruen, D. Andrew Howell, Linbo He, Jingwei Hu, Abdusamatjan Iskandar, Joahan Castaneda Jaims, Ji-An Jiang, Ning Jiang, Shuaijiao Jiang, Runduo Liang, Zhixing Ling, Jialian Liu, Xing Liu, Yuan Liu, Frank J. Masci, Curtis McCully, Megan Newsome, Kanthanakorn Noysena, Kangrui Ni, Antonella Palmese, Han-Long Peng, Josiah Purdum, Yu-Jing Qin, Sam Rose, Ben Rusholme, Cassie Sevilla, Roger Smith, Yujia Song, Niharika Sravan, Robert Stein, Constantin Tabor, Giacomo Terreran, Samaporn Tinyanont, Pablo Vega, Letian Wang, Tinggu Wang, Xiaofeng Wang, Xuefeng Wu, Kathryn Wynn, Yunfei Xu, Shengyu Yan, Weimin Yuan, Binbin Zhang, Chen Zhang, Zipei Zhu, Xiaoxiong Zuo, Gursimran Bhullar + http://creativecommons.org/licenses/by/4.0/ + A. Porredon (DESI Collaboration), C. Blake (DESI Collaboration), J. U. Lange (DESI Collaboration), N. Emas (DESI Collaboration), J. Aguilar (DESI Collaboration), S. Ahlen (DESI Collaboration), A. Bera (DESI Collaboration), D. Bianchi (DESI Collaboration), D. Brooks (DESI Collaboration), F. J. Castander (DESI Collaboration), T. Claybaugh (DESI Collaboration), J. Coloma Nadal (DESI Collaboration), A. Cuceu (DESI Collaboration), K. S. Dawson (DESI Collaboration), A. de la Macorra (DESI Collaboration), Biprateep Dey (DESI Collaboration), P. Doel (DESI Collaboration), A. Elliott (DESI Collaboration), S. Ferraro (DESI Collaboration), A. Font-Ribera (DESI Collaboration), J. E. Forero-Romero (DESI Collaboration), C. Garcia-Quintero (DESI Collaboration), E. Gazta\~naga (DESI Collaboration), S. Gontcho A Gontcho (DESI Collaboration), G. Gutierrez (DESI Collaboration), J. Guy (DESI Collaboration), B. Hadzhiyska (DESI Collaboration), H. K. Herrera-Alcantar (DESI Collaboration), S. Heydenreich (DESI Collaboration), K. Honscheid (DESI Collaboration), C. Howlett (DESI Collaboration), D. Huterer (DESI Collaboration), M. Ishak (DESI Collaboration), S. Joudaki (DESI Collaboration), R. Joyce (DESI Collaboration), D. Kirkby (DESI Collaboration), A. Kremin (DESI Collaboration), A. Krolewski (DESI Collaboration), O. Lahav (DESI Collaboration), C. Lamman (DESI Collaboration), M. Landriau (DESI Collaboration), L. Le Guillou (DESI Collaboration), A. Leauthaud (DESI Collaboration), M. E. Levi (DESI Collaboration), M. Manera (DESI Collaboration), A. Meisner (DESI Collaboration), R. Miquel (DESI Collaboration), S. Nadathur (DESI Collaboration), J. A. Newman (DESI Collaboration), G. Niz (DESI Collaboration), N. Palanque-Delabrouille (DESI Collaboration), W. J. Percival (DESI Collaboration), C. Poppett (DESI Collaboration), F. Prada (DESI Collaboration), I. P\'erez-R\`afols (DESI Collaboration), A. Robertson (DESI Collaboration), G. Rossi (DESI Collaboration), R. Ruggeri (DESI Collaboration), E. Sanchez (DESI Collaboration), C. Saulder (DESI Collaboration), D. Schlegel (DESI Collaboration), M. Schubnell (DESI Collaboration), A. Semenaite (DESI Collaboration), H. Seo (DESI Collaboration), J. Silber (DESI Collaboration), A. Souki (DESI Collaboration), D. Sprayberry (DESI Collaboration), G. Tarl\'e (DESI Collaboration), M. Vargas-Maga\~na (DESI Collaboration), B. A. Weaver (DESI Collaboration), C. Zhou (DESI Collaboration), R. Zhou (DESI Collaboration), H. Zou (DESI Collaboration) - $^{12}$CO $J$=3--2 Observations of Tycho's supernova remnant: constraints on the environmental gas properties - https://arxiv.org/abs/2512.10245 - arXiv:2512.10245v1 Announce Type: new -Abstract: Recent observations suggest that Tycho's supernova remnant (SNR; SN 1572) is expanding into a cavity wall of molecular clouds (MCs), which decelerate the SNR and influence its multi-wavelength morphology. To constrain the physical properties of environmental MCs and search for heated gas, we perform a JCMT $^{12}$CO $J$=3--2 observation and compare with previous $^{12}$CO $J$=2--1, $^{12}$CO $J$=1--0 and $^{13}$CO $J$=1--0 data. We present the $^{12}$CO $J$=3--2 map toward Tycho and show that the $^{12}$CO $J$=3--2 spatial distribution and line profiles are similar to those of the lower-$J$ CO lines. By comparing the multiple transitions of CO and the RADEX (Radiative transfer code in non-Local Thermodynamic Equilibrium) models, we constrain the physical properties of molecular gas surrounding Tycho: the northern cloud has a molecular column density of $N({\rm H}_{2})=0.5$ -- $4.5\times 10^{22}$ cm$^{-2}$, while other regions have $N({\rm H}_{2})=0.2$ -- $3.9\times10^{21}$ cm$^{-2}$; the kinetic temperatures $T_{\rm k}$ of these clouds are in the range of 9 -- 22 K and the volume densities $n({\rm H}_{2})$ are 20 -- $700$ cm$^{-3}$. We also discuss the difficulty in finding hot molecular gas shocked by such a young SNR. We estimate that the shocked molecular layer can be as thin as 0.003 pc, corresponding to $0.2''$ at the distance of 2.5 kpc, which is 2 orders of magnitude smaller than the angular resolution of current CO observations. Therefore, our molecular observations are largely insensitive to the thin shocked gas layer; instead, they detect the environmental gas. - oai:arXiv.org:2512.10245v1 - astro-ph.GA - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Joint cosmological fits to DESI-DR1 full-shape clustering and weak gravitational lensing in configuration space + https://arxiv.org/abs/2512.15961 + arXiv:2512.15961v1 Announce Type: new +Abstract: We present a joint $3\times2$-pt cosmological analysis of auto- and cross-correlations between the Dark Energy Spectroscopic Instrument Data Release 1 (DESI-DR1) Bright Galaxy Survey (BGS) and Luminous Red Galaxy (LRG) samples and overlapping shear measurements from the KiDS-1000, DES-Y3 and HSC-Y3 weak lensing surveys. We perform our analysis in configuration space and, in addition to the cosmic shear correlation functions for each weak lensing dataset, we fit the tangential shear of the weak lensing source galaxies around DESI lens galaxies. Finally, we make use of the anisotropic BGS and LRG clustering information by fitting the full shape of the two-point correlation function multipoles measured over the full DESI-DR1 footprint, presenting the first full-shape analysis of DESI measurements in configuration space. We find that the addition of weak lensing information serves to improve, with respect to the clustering-only case, the measurements of the power spectrum amplitude parameters $\ln(10^{10}A_{\rm{s}})$ and $\sigma_{12}$ by $15\%$ and $36\%$, respectively. It also improves measurements of the linear bias of the lens galaxies by $15-20\%$, depending on the tracer. Our results show excellent consistency, regardless of the weak lensing survey considered, and are furthermore consistent with a companion analysis that fits $3\times2$-pt correlations including DESI projected clustering measurements, as well as the results published by the weak lensing collaborations themselves. Our measured values for weak lensing amplitude are $S_{8}^{\mathrm{DESI\times HSC}}=0.787\pm0.020$, $S_{8}^{\mathrm{DESI\times DES}}=0.791\pm0.016$, $S_{8}^{\mathrm{DESI\times KiDS}}=0.771\pm0.017$, which are $1.9\sigma-2.9\sigma$ below the $S_8$ value preferred by Planck. Finally, our clustering-only results are in good agreement with the Fourier space full-shape analysis of all DESI tracers. + oai:arXiv.org:2512.15961v1 + astro-ph.CO + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Sendi Bo, Yu Huang, Ping Zhou, Tian-Yu Tu, Samar Safi-Harb, Zhi-Yu Zhang, Yang Chen, Hidetoshi Sano + A. Semenaite, C. Blake, A. Porredon, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, F. J. Castander, T. Claybaugh, A. Cuceu, K. S. Dawson, A. de la Macorra, Biprateep Dey, P. Doel, A. Eggemeier, A. Elliott, N. Emas, S. Ferraro, A. Font-Ribera, J. E. Forero-Romero, C. Garcia-Quintero, E. Gazta\~naga, S. Gontcho A Gontcho, G. Gutierrez, J. Guy, B. Hadzhiyska, H. K. Herrera-Alcantar, S. Heydenreich, K. Honscheid, C. Howlett, D. Huterer, M. Ishak, S. Joudaki, R. Joyce, E. Jullo, D. Kirkby, A. Kremin, A. Krolewski, O. Lahav, C. Lamman, M. Landriau, J. U. Lange, L. Le Guillou, A. Leauthaud, M. E. Levi, M. Manera, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, J. A. Newman, N. Palanque-Delabrouille, W. J. Percival, A. Pezzotta, C. Poppett, F. Prada, I. P\'erez-R\`afols, A. Robertson G. Rossi, R. Ruggeri, A. G. S\'anchez, E. Sanchez, C. Saulder, D. Schlegel, M. Schubnell, H. Seo, J. Silber, D. Sprayberry, G. Tarl\'e, B. A. Weaver, P. Zarrouk, R. Zhou, H. Zou - Irregularity in Active Fast Radio Burst Repeaters and Magnetar Periodic Radio Pulses: Time, Energy, and Frequency Analyses - https://arxiv.org/abs/2512.10249 - arXiv:2512.10249v1 Announce Type: new -Abstract: Fast Radio Bursts (FRBs) are millisecond-duration radio pulses with largely unknown origins, with a subset exhibiting repeating behavior. Magnetars highly magnetized neutron stars and a leading progenitor candidate for FRBs also produce similar but much fainter millisecond radio pulses, suggesting a possible connection between the two phenomena. The irregularity of the time series of repeating FRBs and magnetar pulses may provide insight into the underlying progenitor activity. In this study, we analyze time-series data from three repeating FRB sources (four datasets) and the Galactic magnetar SGR J1935+2154 to investigate potential patterns in burst arrival times, energy fluctuations, and peak-frequency shifts. We quantify the degree of randomness (Pincus Index; PI) and chaos (Largest Lyapunov Exponent; LLE) for these three parameters. We find that waiting times across all repeating FRBs exhibit high PI (high randomness) and low LLE (low chaos), consistent with the behavior of magnetar radio pulses. This similarity suggests that both may share a common triggering mechanism. In contrast, the energy fluctuations of both repeating FRBs and magnetar pulses occupy the same region in PI-LLE phase space but display much larger scatter than the other two domains. We discuss the possibility that beaming effects or strong variability in radio-emission efficiency may explain their distinct behavior in the energy domain. - oai:arXiv.org:2512.10249v1 - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Cosmological Constraints from Full-Scale Clustering and Galaxy-Galaxy Lensing with DESI DR1 + https://arxiv.org/abs/2512.15962 + arXiv:2512.15962v1 Announce Type: new +Abstract: We present constraints on cosmic structure growth from the analysis of galaxy clustering and galaxy-galaxy lensing with galaxies from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1. We analyze four samples drawn from the Bright Galaxy Survey (BGS) and the Luminous Red Galaxy (LRG) target classes. Projected galaxy clustering measurements from DESI are supplemented with lensing measurements from the Dark Energy Survey (DES), the Kilo-Degree Survey (KiDS), and the Hyper Suprime-Cam (HSC) survey around the same targets. Our method relies on a simulation-based modeling framework using the AbacusSummit simulations and a complex halo occupation distribution model that incorporates assembly bias. We analyze scales down to $0.4 \, h^{-1} \, \mathrm{Mpc}$ for clustering and $2.5 \, h^{-1} \, \mathrm{Mpc}$ for lensing, leading to stringent constraints on $S_8 = \sigma_8 \sqrt{\Omega_\mathrm{m} / 0.3}$ and $\Omega_\mathrm{m}$ when fixing other cosmological parameters to those preferred by the CMB. We find $S_8 = 0.794 \pm 0.023$ and $\Omega_\mathrm{m} = 0.295 \pm 0.012$ when using lensing measurements from DES and KiDS. Similarly, for HSC, we find $S_8 = 0.793 \pm 0.017$ and $\Omega_\mathrm{m} = 0.303 \pm 0.010$ when assuming the best-fit photometric redshift offset suggested by the HSC collaboration. Overall, our results are in good agreement with other results in the literature while continuing to highlight the constraining power of non-linear scales. + oai:arXiv.org:2512.15962v1 + astro-ph.CO + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Ellen C. C. Lin, Shotaro Yamasaki, Tomotsugu Goto, Tetsuya Hashimoto + Johannes U. Lange, Alexandra Wells, Andrew Hearin, Gillian Beltz-Mohrmann, Alexie Leauthaud, Sven Heydenreich, Chris Blake, Jessica Nicole Aguilar, Steven Ahlen, Abhijeet Anand, Davide Bianchi, David Brooks, Francisco Javier Castander, Todd Claybaugh, Shaun Cole, Andrei Cuceu, Kyle Dawson, Axel de la Macorra, Biprateep Dey, Peter Doel, Ann Elliott, Ni Putu Audita Placida Emas, Simone Ferraro, Andreu Font-Ribera, Jaime E. Forero-Romero, Cristhian Garcia-Quintero, Enrique Gazta\~naga, Satya Gontcho A Gontcho, Gaston Gutierrez, Julien Guy, Klaus Honscheid, Dragan Huterer, Mustapha Ishak, Shahab Joudaki, Dick Joyce, Robert Kehoe, David Kirkby, Theodore Kisner, Anthony Kremin, Alex Krolewski, Ofer Lahav, Claire Lamman, Martin Landriau, Laurent Le Guillou, Michael Levi, Marc Manera, Paul Martini, Aaron Meisner, Ramon Miquel, John Moustakas, Eva-Maria Mueller, Seshadri Nadathur, Jeffrey A. Newman, Gustavo Niz, Nathalie Palanque-Delabrouille, Will Percival, Claire Poppett, Anna Porredon, Francisco Prada, Ignasi P\'erez-R\`afols, Amy Robertson, Graziano Rossi, Rossana Ruggeri, Eusebio Sanchez, Christoph Saulder, David Schlegel, Michael Schubnell, Agne Semenaite, Hee-Jong Seo, Joseph Harry Silber, David Sprayberry, Zechang Sun, Gregory Tarl\'e, Mariana Vargas Magana, Benjamin Alan Weaver, Risa Wechsler, Pauline Zarrouk, Rongpu Zhou, Hu Zou - Relaxation of time-variable neutron-loaded relativistic jets across the photosphere and their GeV-TeV neutrino counterparts - https://arxiv.org/abs/2512.10253 - arXiv:2512.10253v1 Announce Type: new -Abstract: Both observational and theoretical studies indicate that the central engine of a gamma-ray burst (GRB) is intrinsically time-variable, implying jet inhomogeneity. A jet with an inhomogeneous Lorentz factor distribution develops internal shocks both below and above the photosphere, relaxing toward homologous expansion. Below the photosphere, neutrons, whose mean free paths are much longer than those of charged particles, play an essential role in the dissipation process. Using neutron-inclusive shell simulations with initial conditions based on the collapsar scenario, we link the statistical inhomogeneity of the jet at the breakout of the progenitor to the dissipation that occurs inside and outside the photosphere, and calculate the GeV-TeV neutrino counterpart originated from inelastic neutron-proton interactions consistently with the prompt gamma-ray emission. We find that the peak energy of the GeV-TeV neutrinos is in 10-30 GeV irrespective to the baryon loading factor of the jet, with the high-energy tail extending into the TeV range as the amplitude of the time variability becomes stronger. When gamma-ray emission is efficient as in typical GRBs (i.e., the gamma-ray radiation efficiency with respect to the total jet power is approximately 100%, the radiative efficiency of GeV-TeV neutrinos remains 0.1-10%. By contrast, when the gamma-ray radiation efficiency is relatively low (< 10%) for jets where a large fraction of the energy is dissipated below the photosphere, the neutrino efficiency can increase up to 20%. This suggests that GRBs with relatively low gamma-ray luminosities, as well as X-ray-rich transients, can be promising targets for ongoing and future GeV-TeV neutrino transient searches. - oai:arXiv.org:2512.10253v1 - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Clustering redshift distribution calibration of weak lensing surveys using the DESI-DR1 spectroscopic dataset + https://arxiv.org/abs/2512.15963 + arXiv:2512.15963v1 Announce Type: new +Abstract: We estimate the source redshift distribution of current weak lensing surveys by applying the clustering-based redshift calibration technique, using the galaxy redshift sample provided by the Dark Energy Spectroscopic Instrument Data Release 1 (DESI-DR1). We cross-correlate the Bright Galaxy Survey (BGS), Luminous Red Galaxies (LRGs) and Emission Line Galaxies (ELGs) from DESI, within the redshift range $0.1 < z < 1.6$, with overlapping tomographic source samples from the Dark Energy Survey (DES), Kilo-Degree Survey (KiDS), and Hyper Suprime-Cam (HSC) survey. Using realistic mock catalogues, we test the stability of the clustering-redshift signal to fitting scale, reference-sample choice, and the evolution of source galaxy bias, and we explicitly model and marginalise over magnification contributions, which become non-negligible at $z \gtrsim 1$ due to the depth of the DESI ELG sample. We then compare the resulting bias-weighted redshift distributions to those calibrated using self-organising map (SOM) techniques, finding agreement within uncertainties for all surveys and tomographic bins. Our results demonstrate that clustering redshifts enabled by DESI's unprecedented spectroscopic sample provides a robust, complementary, and independent constraint capable of reducing one of the dominant systematic uncertainties in weak lensing cosmology. + oai:arXiv.org:2512.15963v1 + astro-ph.CO + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kanako Nakama, Kazumi Kashiyama, Nobuhiro Shimizu + http://creativecommons.org/licenses/by/4.0/ + R. Ruggeri, C. Blake, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, F. J. Castander, T. Claybaugh, A. Cuceu, K. S. Dawson, A. de la Macorra, B. Dey, P. Doel, A. Elliott, N. Emas, S. Ferraro, A. Font-Ribera, J. E. Forero-Romero, C. Garcia-Quintero, E. Gazta\~naga, S. Gontcho A Gontcho, G. Gutierrez, J. Guy, B. Hadzhiyska, H. K. Herrera-Alcantar, S. Heydenreich, K. Honscheid, C. Howlett, D. Huterer, M. Ishak, S. Joudaki, R. Joyce, D. Kirkby, A. Krolewski, O. Lahav, C. Lamman, M. Landriau, J. U. Lange, A. Leauthaud, M. E. Levi, M. Manera, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, J. A. Newman, W. J. Percival, C. Poppett, A. Porredon, F. Prada, I. P\'erez-R\`afols, A. Robertson, G. Rossi, E. Sanchez, C. Saulder, D. Schlegel, M. Schubnell, A. Semenaite, H. Seo, J. Silber, D. Sprayberry, G. Tarl\'e, B. A. Weaver, P. Zarrouk, R. Zhou, H. Zou - Hybrid corona and transient soft X-ray lags in Fairall 9 - https://arxiv.org/abs/2512.10261 - arXiv:2512.10261v1 Announce Type: new -Abstract: Fairall 9 is among the most massive Seyfert galaxies exhibiting a strong soft X-ray excess, but it is challenging to probe soft X-ray reverberation lags (if any) due to the long intrinsic timescales expected from its large black hole mass of $\sim 2.55 \times 10^8 M_\odot$. We fit five XMM-Newton spectra of Fairall 9 using the hybrid reXcor model taking into account both hot and warm corona. The soft excess is explained by a combination of a physically motivated warm corona and the disc reflection. Then, we perform a wavelet coherence analysis of the light curves between 0.3 - 1 and 1 - 4 keV bands. The spectral fits are consistent with a rapidly spinning black hole ($a = 0.99$), a warm corona with optical depth $\sim$10 - 30, and a hot lamp-post corona located at either 5 or $20~r_{\rm g}$. This configuration supports a coexisting hot and warm corona scenario, allowing the disc to extend almost to the event horizon. Our wavelet analysis on combined observations reveals signatures of transient soft X-ray lags, confined to specific time-frequency intervals. The earlier observations exhibit more variable and transient lag behavior. In contrast, the later observations display more persistent soft X-ray lags at the frequencies of $\sim 9\times 10^{-6}$ - $2.5 \times 10^{-5}$ Hz, with amplitudes reaching $\sim$1000 s. The results indicate a progressively stable disc-corona configuration in later observations. Given the mass and geometry of Fairall 9, the observed soft lags appears plausibly consistent in both size and timescales with expectations from X-ray reverberation. - oai:arXiv.org:2512.10261v1 - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + The Power of DESI for Photometric Redshift Calibration: A Case Study with KiDS-1000 + https://arxiv.org/abs/2512.15964 + arXiv:2512.15964v1 Announce Type: new +Abstract: Accurate redshift estimates are a critical requirement for weak lensing surveys and one of the main uncertainties in constraints on dark energy and large-scale cosmic structure. In this paper, we study the potential to calibrate photometric redshift (photo-z) distributions for gravitational lensing using the Dark Energy Spectroscopic Instrument (DESI). Since beginning its science operations in 2021, DESI has collected more than 50 million redshifts, adding about one million monthly. In addition to its large-scale structure samples, DESI has also acquired over 256k high-quality spectroscopic redshifts (spec-zs) in the COSMOS and XMM and VVDS fields. This is already a factor of 3 larger than previous spec-z calibration compilations in these two regions. Here, we explore calibrating photo-zs for the subset of KiDS-1000 galaxies that fall into joint self-organizing map (SOM) cells overlapping the DESI COSMOS footprint using the DESI COSMOS observations. Estimating the redshift distribution in KiDS-1000 with the new DESI data, we find broad consistency with previously published results while also detecting differences in the mean redshift in some tomographic bins with an average shifts of Delta Mean(z) = -0.028 in the mean and Delta Median(z) = +0.011 in the median across tomographic bins. However, we also find that incompleteness per SOM cell, i.e., groups of galaxies with similar colors and magnitudes, can modify n(z) distributions. Finally, we comment on the fact that larger photometric catalogs, aligned with the DESI COSMOS and DESI XMM and VVDS footprints, would be needed to fully exploit the DESI dataset and would extend the coverage to nearly eight times the area of existing 9-band photometry. + oai:arXiv.org:2512.15964v1 + astro-ph.CO + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - K. Khanthasombat, P. Chainakun, W. Luangtip, J. Jiang, A. J. Young + http://creativecommons.org/licenses/by/4.0/ + Diana Blanco, Alexie Leauthaud, Johannes Ulf Lange, Angus Wright, Hendrik Hildebrandt, Sven Heydenreich, Darshika Ravulapalli, Joshua Ratajczak, Kyle Dawson, Jamie McCullough, Biprateep Dey, Chris Blake, Ni Putu Audita Placida Emas, Cristhian Garcia-Quintero, Shahab Joudaki, Alex Krolewski, Anna Porredon, Graziano Rossi, Christoph Saathoff, David Schlegel, Lily Schmassmann, Samantha Y. Skirlo, Jennifer A. Tinker, Mario Alberto G. Maia, Aihara Hiroaki, Manuel Carrasco Kind, John N. Bahcall, Stephan J. Bailey, Jordi Miralda-Escud\'e, Michael R. Blanton, William C. Brown, John E. Carlson, Daniel J. Eisenstein, Daniel Forero-Romero, Andreu Font-Ribera, David W. Hogg, Klaus Honscheid, Jean-Paul Kneib, Arjun Dey, Stephen Bailey, Nikhil Padmanabhan, Julian E. Bautista, Julien Guy, Julien Delubac, Kyle G. Mohr, Robert C. Nichol, John Peacock, Martin White, David H. Weinberg, Christophe Yeche, Ryan Keenan, Xiaohui Fan, Daniel Kirkby, John Moustakas, Aaron Meisner, Christophe Pichon, Martin Crocce, David Sprayberry, Gregory Tarl\'e, Benjamin Alan Weaver, Rongpu Zhou, Hu Zou - Detectability of Atmospheric Biosignatures in Earth Analogs with Varying Surface Boundary Conditions: Prospects for Characterization in the UV, Visible, Near-Infrared, and Mid-Infrared Regions - https://arxiv.org/abs/2512.10277 - arXiv:2512.10277v1 Announce Type: new -Abstract: The search for potentially habitable exoplanets centers on detecting biosignature molecules in Earth-like atmospheres, which makes it essential to understand their detectability under biologically and geologically influenced conditions. In this study, we model the reflection and thermal emission spectra of such atmospheres across the UV/VIS/NIR and mid-IR regions and simulate their detectability with future mission concepts such as the Habitable Worlds Observatory (HWO) and the Large Interferometer for Exoplanets (LIFE). We employ Numerical Weather Prediction (NWP) model data, based on Earth's atmosphere, to derive temperature pressure profiles and couple them with a 1D photochemical model to assess the detectability of these molecules in Earth analogs located 10 parsecs away. We investigate the dominant reaction pathways and their contributions to the atmospheric composition of an Earth analog, with a focus on how they shape the resulting molecular signatures. We also examine the role of surface boundary conditions, which indirectly trace the effects of biological and geological processes, on the detectability of these molecules using HWO- and LIFE-type mission concepts. Our findings indicate that O3 is detectable with both mission concepts, while H2O requires specific surface humidity levels for detection with LIFE and shows only potential detectability with HWO. CO2 is detectable with LIFE. Both N2O and CH4 require continuous surface outgassing for potential detection with LIFE, and CH4 further requires low surface humidity to prevent masking by water features. Our work highlights the feasibility of characterizing the atmospheres of Earth analogs in the UV/VIS/NIR and mid-IR domains using HWO- and LIFE-type mission concepts and offers guidance for the development of future missions operating in these spectral regions. - oai:arXiv.org:2512.10277v1 + The Sesquinary Catastrophe on Deimos can reconcile its excited past with its dynamically cool present + https://arxiv.org/abs/2512.15976 + arXiv:2512.15976v1 Announce Type: new +Abstract: The origins of the Martian moons Phobos and Deimos are highly debated, and hypotheses include formation from an impact-generated circum-Martian disk or from capture of asteroids. With the impact scenario, Deimos (or its precursors) were formed or were pushed out beyond the synchronous orbit of Mars. Moons interior to the synchronous orbit, including Phobos (or its precursors), would tidally evolve and resonances between these moons could potentially excite Deimos' orbit. This contradicts Deimos' present-day orbit of low eccentricity ($0.00027$) and moderate inclination ($1.8^\circ$ to the Laplace plane). Tidal dissipation within Deimos is too inefficient for eccentricity damping, and without alternative mechanisms, Deimos' present-day orbit places strong constraints on the evolution of any inner moons. We propose that a runaway collisional cascade called the "sesquinary catastrophe'' acts as a natural barrier that prevents Deimos from having a more excited orbit. Using N-body simulations with collisional fragmentation, we show that if Deimos was more excited, it would undergo a sesquinary catastrophe and break apart into a Roche-exterior debris disk. Using a measure of sesquinary orbital excitation called $q$, our simulations and previous works suggest that breakup occurs for $q \gtrsim 8$ on timescales of $\sim 10^{3-4}$ years. If Deimos was destroyed in a sesquinary catastrophe and re-accreted from a (likely collisionally) damped debris disk, it should be a porous sand-pile moon, consistent with its smooth surface. The sesquinary catastrophe can be applied to other Deimos-like planetary moons at $q \gtrsim 8$. + oai:arXiv.org:2512.15976v1 astro-ph.EP - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Dibya Bharati Pradhan, Priyankush Ghosh, Oommen P. Jose, Liton Majumdar + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Kaustub P. Anand, Matija \'Cuk, David A. Minton - MorphZ: Enhancing evidence estimation through the Morph approximation - https://arxiv.org/abs/2512.10283 - arXiv:2512.10283v1 Announce Type: new -Abstract: We introduce the Morph approximation, a class of product approximations of probability densities that selects low-order disjoint parameter blocks by maximizing the sum of their total correlations. We use the posterior approximation via Morph as the importance distribution in optimal bridge sampling. We denote this procedure by MorphZ, which serves as a post-processing estimator of the marginal likelihood. The MorphZ estimator requires only posterior samples together with the prior and likelihood, and is fully agnostic to the choice of sampler. We evaluate MorphZ's performance across statistical benchmarks, pulsar timing array (PTA) models, compact binary coalescence (CBC) gravitational-wave (GW) simulations and the GW150914 event. Across these applications, spanning low to high dimensionalities, MorphZ yields accurate evidence at substantially reduced computational cost relative to standard approaches, and can improve these estimates even when posterior coverage is incomplete. Its bridge sampling relative error diagnostic provides conservative uncertainty estimates. Because MorphZ operates directly on posterior draws, it complements exploration-oriented samplers by enabling fast and reliable evidence estimation, while it can be seamlessly integrated into existing inference workflows. - oai:arXiv.org:2512.10283v1 - astro-ph.IM - astro-ph.CO - physics.data-an - Fri, 12 Dec 2025 00:00:00 -0500 + MAGellanic Outflow and chemistry Survey (MAGOS): Hot cores in the LMC + https://arxiv.org/abs/2512.15983 + arXiv:2512.15983v1 Announce Type: new +Abstract: The Large Magellanic Cloud (LMC) provides a key laboratory for exploring the diversity of star formation and interstellar chemistry under subsolar metallicity conditions. We present the results of a hot core survey toward 30 massive protostellar objects in the LMC using the Atacama Large Millimeter/submillimeter Array (ALMA) at 350 GHz. Continuum imaging reveals 36 compact sources in total, among which line analyses identify 9 hot cores and 1 hot-core candidate, including two newly identified sources. We detect CO, HCO+, H13CO+, HC15N, HC3N, SiO, SO, SO+, NS, SO2, 34SO2, 33SO2, CH3OH, 13CH3OH, HCOOH, HCOOCH3, CH3OCH3, C2H5OH, H2CCO (tentative), and hydrogen recombination lines from hot cores. CH3OCH3, a complex organic molecule larger than CH3OH, is detected for the first time in a hot core outside the LMC bar region. All hot cores show stronger emission in the high-excitation SO line compared to non-hot-core sources, suggesting that its strong detection will be useful for identifying hot-core candidates in the LMC. Chemical analysis reveals a spread of more than two orders of magnitude in CH3OH abundances, with some sources deficient in COMs. In contrast, SO2 is detected in all hot cores, and its abundance shows a good correlation with rotational temperature. The hot cores without CH3OH detections are all located outside the LMC bar region and are characterized by either high luminosity or active star formation in their surroundings. A combination of locally low metallicity, active star formation in the vicinity, and high protostellar luminosity may jointly trigger the COM-poor hot core chemistry observed in the LMC. + oai:arXiv.org:2512.15983v1 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - El Mehdi Zahraoui, Patricio Maturana-Russel, Avi Vajpeyi, Willem van Straten, Renate Meyer, Sergei Gulyaev + Takashi Shimonishi, Kei E. I. Tanaka, Yichen Zhang, Kenji Furuya, Yu Cheng, Asako Sato - Tracking Protostellar Variability in Massive Protoclusters with ALMA: I. Insights from QUARKS and MaMMOtH - https://arxiv.org/abs/2512.10298 - arXiv:2512.10298v1 Announce Type: new -Abstract: Millimeter/submillimeter variability is often attributed to dynamical disk-mediated accretion, yet detection is limited to low-mass protostars in nearby clouds. Recent observations have also revealed significant (sub)millimeter variability in high-mass protostars, but the confirmed cases are scarce and lack systematic monitoring. In this work, we analyzed multi-epoch Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 (1.3 mm) continuum observations of 22 massive protoclusters, with epoch separations ranging from a few hours to more than two years, while achieving a consistent angular resolution of approximately 0.3 arcsec. These data allow us to track variability of protostars across a broader mass range and in an environment markedly different from nearby clouds. Using a custom processing pipeline for data reduction, image alignment, and relative flux calibration, we achieve high-precision flux measurements and, for the first time, investigate millimeter variability in massive protoclusters based on interferometric data in a statistical manner. Applying the astrodendro algorithm, we identified 383 condensations and tracked their variations in peak intensities. Standard deviation analysis and difference maps reveal five variable sources, corresponding to a lower limit of 1.3% on the variable fraction. Among these, I13111-6228 stands out as it hosts a hypercompact H II region that exhibits a 68% increase in continuum peak intensity over one year, with an uncertainty of 2%. This supports the burst-mode accretion picture in massive star formation as a viable route for the formation of massive stars. - oai:arXiv.org:2512.10298v1 + ASKAP discovery of a 30 kpc bipolar outflow from the edge-on disk of the nearby spiral galaxy ESO 130-G012 + https://arxiv.org/abs/2512.15991 + arXiv:2512.15991v1 Announce Type: new +Abstract: We present the discovery of a large-scale, limb-brightened outflow, extending at least 30 kpc above and below the star-forming disk of the edge-on galaxy ESO 130-G012 (D = 16.9 Mpc). Partially obscured by Galactic foreground stars and dust, this optically unremarkable, low-mass galaxy reveals one of the largest known hourglass-shaped outflows from the full extent of its bright stellar disk. The outflow was discovered in 944 MHz radio continuum images from the Australian Square Kilometre Array Pathfinder (ASKAP) obtained as part of the "Evolutionary Map of the Universe" (EMU) project. Its height is at least 3x that of the stellar disk diameter (~10 kpc), while its shape and size most resemble the large biconical, edge-brightened FUV and X-ray outflows in the nearby starburst galaxy NGC 3079. The large-scale, hourglass-shaped outflow of ESO 130-G012 appears to be hollow and originates from the star-forming disk, expanding into the halo with speeds close to the escape velocity before likely returning to the disk. Given ESO 130-G012's modest star formation rate, the height of the outflow is surprising and unusual, likely made possible by the galaxy's relatively low gravitational potential. Follow-up observations are expected to detect hot gas inside the bipolar outflow cones and magnetic fields along the X-shaped outflow wings. Neutral gas may also be lifted above the inner disk by the outflow. + oai:arXiv.org:2512.15991v1 astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yuhan Yang, Tie Liu, Sheng-Yuan Liu, Doug Johnstone, Gregory Herczeg, Wenyu Jiao, Yu-Nung Su, Xiaofeng Mai, Fengwei Xu, Dominique Meyer, Siju Zhang, Eduard Vorobiev, Suinan Zhang, Qiuyi Luo, Guido Garay, Xi Chen, Yunfan Jiao, Qi-lao Gu, Yan-kun Zhang, Ken'ichi Tatematsu, Andrey Sobolev, Sergey Parfenov, Leonardo J. Bronfman + http://creativecommons.org/licenses/by/4.0/ + Baerbel S. Koribalski (Australia Telescope National Facility, CSIRO, Space and Astronomy, Australia, Western Sydney University, Australia), Roland M. Crocker (Research School of Astronomy and Astrophysics, Australian National University, Australia), Ildar Khabibullin (Universitaets-Sternwarte, Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Germany, Max-Planck-Institut fuer Astrophysik, Germany), Anna Ivleva (Universitaets-Sternwarte, Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Germany), Klaus Dolag (Universitaets-Sternwarte, Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Germany, Max-Planck-Institut fuer Astrophysik, Germany), Umberto Maio (Italian National Institute of Astrophysics - Astronomical Observatotry of Trieste, Italy, Institute for Fundamental Physics of the Universe, Trieste, Italy), Ralf-Juergen Dettmar (Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute), Jacco Th. van Loon (Lennard-Jones Laboratories, Keele University, UK), Stanislav Shabala (School of Natural Sciences, University of Tasmania, Hobart, Australia) - Refined M-type Star Catalog from LAMOST DR10: Measurements of Radial Velocities, $T_\text{eff}$, log $g$, [M/H] and [$\alpha$/M] - https://arxiv.org/abs/2512.10337 - arXiv:2512.10337v1 Announce Type: new -Abstract: Precise stellar parameters for M-type stars, the Galaxy's most common stellar type, are crucial for numerous studies. In this work, we refined the LAMOST DR10 M-type star catalog through a two-stage process. First, we purified the catalog using techniques including deep learning and color-magnitude diagrams to remove 22,496 non-M spectra, correct 2,078 dwarf/giant classifications, and update 12,900 radial velocities. This resulted in a cleaner catalog containing 870,518 M-type spectra (820,493 dwarfs, 50,025 giants). Second, applying a label transfer strategy using values from APOGEE DR16 for parameter prediction with a ten-fold cross-validated CNN ensemble architecture, we predicted $T_\text{eff}$, $\log g$, [M/H], and [$\alpha$/M] separately for M dwarfs and giants. The average internal errors for M dwarfs/giants are respectively: $T_\text{eff}$ 30/17 K, log $g$ 0.07/0.07 dex, [M/H] 0.07/0.05 dex, and [$\alpha$/M] 0.02/0.02 dex. Comparison with APOGEE demonstrates external precisions of 34/14 K, 0.12/0.07 dex, 0.09/0.04 dex, and 0.03/0.02 dex for M dwarfs/giants, which represents precision improvements of over 20\% for M dwarfs and over 50\% for M giants compared to previous literature results. The catalog is available at https://nadc.china-vo.org/res/r101668/. - oai:arXiv.org:2512.10337v1 + IPA. Accretion rate of a low-mass Class 0 protostar, measured via mid-infrared fluorescent OH emission + https://arxiv.org/abs/2512.15999 + arXiv:2512.15999v1 Announce Type: new +Abstract: The earliest stages of star formation are highlighted by complex interactions between accretion, outflow, and radiative processes, which shape the chemical and physical environment of the emerging protostar. James Webb Space Telescope observations of the low-mass, low-luminosity Class 0 protostar IRAS 16253-2429 reveal a central compact source. This object exhibits a rich mid-infrared emission spectrum of OH pure rotational lines and $\rm CO_2$ ro-vibrational lines. Unusually for a young stellar object, it has no mid-infrared line emission from $\rm H_2O$ to match the other molecules. We demonstrate that the emitting OH molecules arise from UV photodissociation of $\rm H_2O$ in its second absorption band at $\lambda = 114-145$ nm, and that the OH emission is a fluorescent cascade starting with highest-excitation rotational states. This situation offers the opportunity of using the infrared OH spectrum to measure the UV flux from the central protostar. Thereby we determine the disk-star accretion rate to be $3 \times 10^{-10} \ M_\sun \ {\rm year^{-1}}$, and demonstrate that the system luminosity arises mostly from the protostar's photosphere rather than from accretion luminosity. The result is in accord with the measured outflow rate of IRAS 16253-2429 and lies within the outflow/accretion-flow rate trend often inferred for protostars; and with episodic accretion as the dominant mechanism by which this protostar has grown. + oai:arXiv.org:2512.15999v1 astro-ph.SR astro-ph.GA - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 10.3847/1538-4365/ae1586 - Shuo Li et al 2025 ApJS 281 58 - Shuo Li, Yin-Bi Li, A-Li Luo, Jun-Chao Liang, You-Fen Wang, Jing Chen, Shuo Zhang, Mao-Sheng Xiang, Hugh R. A. Jones, Zhong-Rui Bai, Xiao-Xiao Ma, Yun-Jin Zhang, Hai-Ling Lu + Dan M. Watson, Mayank Narang, Caeley V. Pittman, Himanshu Tyagi, Robert Gutermuth, Adam E. Rubinstein, Neal J. Evans II, Lee W. Hartmann, S. Thomas Megeath, P. Manoj, Catherine C. Espaillat, Nuria Calvet, Alessio Caratti o Garatti, Ewine F. van Dishoeck, Tyler L. Bourke, Joel D. Green, Carey M. Lisse, Pamela Klaassen, Leslie W. Looney, Pooneh Nazari, David A. Neufeld, John J. Tobin, Scott J. Wolk, Guillem Anglada, Prabhani Atnagulov, Henrik Beuther, Nashanty G. C. Brunken, Samuel Federman, Elise Furlan, Nolan Habel, Nicole Karnath, Hendrik Linz, James Muzerolle Page, Mayra Osorio, Riwaj Pokhrel, Rohan Rahatgaonkar, Will R. M. Rocha, Patrick D. Sheehan, Katerina Slavicinska, Thomas Stanke, Amelia M. Stutz, Lukasz Tychoniec, Yao-Lun Yang, William J. Fischer - Improved Identification of Strongly Lensed Gravitational Waves with Host Galaxy Locations - https://arxiv.org/abs/2512.10344 - arXiv:2512.10344v1 Announce Type: new -Abstract: We present a Bayesian framework that enhances the identification of strongly lensed gravitational waves (GWs) by incorporating informative positional priors from the Euclid galaxy lens catalog. The core of our method introduces a two-step reweighting scheme: first, gravitational wave parameter estimation is performed under a uniform sky prior; the resulting posterior is then used to reweight galaxy positions within the Euclid catalog, constructing an astrophysically informed positional prior. Comparing this Euclid-informed prior against a uniform prior within our framework reveals distinct behaviors. While the posterior estimates of the intrinsic waveform parameters show little sensitivity to the prior change, the Bayes factor for lensing identification exhibits significant prior dependence. Crucially, for truly lensed event pairs, the Bayes factor systematically increases, whereas for unlensed pairs it decreases. This dual effect is vital for robust discrimination. Our analysis demonstrates that this multi-messenger approach significantly improves the confidence of lensing searches. For lensed pairs, the method boosts the Bayes factor by an average factor of $\sim 10$, while effectively suppressing false positives for unlensed coincidences. This underscores the critical importance of prior specification and showcases the substantial gains achievable by synergizing gravitational-wave data with electromagnetic survey information. - oai:arXiv.org:2512.10344v1 - astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + HEGS : Revisiting a decade of H.E.S.S. extragalactic observations + https://arxiv.org/abs/2512.16005 + arXiv:2512.16005v1 Announce Type: new +Abstract: During its first phase, from 2004 up to the end of 2012, the H.E.S.S. (High Energy Stereoscopic System) experiment observed the extragalactic skies for more than 2700 hours. These data have been re-analysed in a single consistent framework, leading to the derivation of a catalog of 23 sources. In total, about 5.7% of the sky was observed, allowing for several additional studies to be conducted: source variability, extragalactic gamma-ray background light, and comparison with the Fermi-LAT catalogues. In this contribution, we discuss these results and present the high-level data (catalogs, maps) released to the astrophysical community. + oai:arXiv.org:2512.16005v1 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Tonghua Liu, Kai Liao + http://creativecommons.org/licenses/by-nc-nd/4.0/ + 10.22323/1.501.0585 + PoS(ICRC2025)585 + Fran\c{c}ois Brun (for the H.E.S.S. Collaboration), David Sanchez (for the H.E.S.S. Collaboration), Andrew M. Taylor (for the H.E.S.S. Collaboration), Matteo Cerruti (for the H.E.S.S. Collaboration), Jean-Philippe Lenain (for the H.E.S.S. Collaboration) - Estimating stellar atmospheric parameters and elemental abundances using fully connected residual network - https://arxiv.org/abs/2512.10345 - arXiv:2512.10345v1 Announce Type: new -Abstract: Stellar atmospheric parameters and elemental abundances are traditionally determined using template matching techniques based on high-resolution spectra. However, these methods are sensitive to noise and unsuitable for ultra-low-resolution data. Given that the Chinese Space Station Telescope (CSST) will acquire large volumes of ultra-low-resolution spectra, developing effective methods for ultra-low-resolution spectral analysis is crucial. In this work, we investigated the Fully Connected Residual Network (FCResNet) for simultaneously estimating atmospheric parameters ($T_\text{eff}$, $\log g$, [Fe/H]) and elemental abundances ([C/Fe], [N/Fe], [Mg/Fe]). We trained and evaluated FCResNet using CSST-like spectra (\textit{R} $\sim$ 200) generated by degrading LAMOST spectra (\textit{R} $\sim$ 1,800), with reference labels from APOGEE. FCResNet significantly outperforms traditional machine learning methods (KNN, XGBoost, SVR) and CNN in prediction precision. For spectra with g-band signal-to-noise ratio greater than 20, FCResNet achieves precisions of 78 K, 0.15 dex, 0.08 dex, 0.05 dex, 0.10 dex, and 0.05 dex for $T_\text{eff}$, $\log g$, [Fe/H], [C/Fe], [N/Fe] and [Mg/Fe], respectively, on the test set. FCResNet processes one million spectra in only 42 seconds while maintaining a simple architecture with just 348 KB model size. These results suggest that FCResNet is a practical and promising tool for processing the large volume of ultra-low-resolution spectra that will be obtained by CSST in the future. - oai:arXiv.org:2512.10345v1 - astro-ph.IM - astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + Exploring the Galactic Plane: A Comparative Study of Fermi-LAT Sources and HESS's Non-Detection at TeV Energies + https://arxiv.org/abs/2512.16009 + arXiv:2512.16009v1 Announce Type: new +Abstract: The HESS Galactic Plane Survey (HGPS), published in 2018, presented a decade of very-high-energy (VHE) gamma-ray observations along the Galactic plane. This study was accompanied by the release of several maps in FITS format, offering a detailed view of the region. The flux upper-limits from these HGPS maps can be compared to the high-energy (HE) spectra of sources catalogued by the Fermi-LAT in the same region. For some sources, extrapolating the Fermi-LAT flux into the VHE range predicts flux values exceeding the upper-limits set by HESS. In this work, we present the results of this comparison and highlight the sources that are of particular interest for future VHE observations. + oai:arXiv.org:2512.16009v1 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - 10.1088/1674-4527/ae06ff - Shuo Li et al 2025 Res. Astron. Astrophys. 25 125009 - Shuo Li, Yin-Bi Li, A-Li Luo, Jun-Chao Liang, Hai-Ling Lu, Hugh R. A. Jones + http://creativecommons.org/licenses/by-nc-nd/4.0/ + 10.22323/1.501.0584 + PoS(ICRC2025)584 + Fran\c{c}ois Brun, Baptiste Le Nagat-Neher, Marianne Lemoine-Goumard, Marie-H\'el\`ene Grondin, Paul Fauverge - The LEGA-C galaxy survey: multiple quenching channels for quiescent galaxies at $z\sim1$ - https://arxiv.org/abs/2512.10383 - arXiv:2512.10383v1 Announce Type: new -Abstract: We analyzed the sizes and star-formation histories (SFHs) of 2908 galaxies with $M_\star \geq 10^9$ M$_\odot$ at $0.6 < z < 1.0$, drawn from the LEGA-C survey. The goal is to investigate the connection between galaxy sizes with SFH, stellar age, and metallicity. SFHs were derived with Prospector by fitting the high signal-to-noise, high spectral resolution spectroscopy drawn from the LEGA-C DR3 together with the broadband photometry from the UltraVISTA catalog. Galaxy sizes were measured by fitting a 2D S{\'e}rsic profile to the HST ACS~F814W images. We find diverse SFHs and quenching timescales ($\tau_\rm{q}$). The main quiescent population quenched over $\tau_\rm{q}=1.23\pm0.04$ Gyr, whereas compact post-starburst galaxies (PSBs) quenched much faster, $\tau_\rm{q}=0.13\pm0.03$ Gyr. At fixed stellar mass, smaller quiescent galaxies quenched more rapidly than larger ones; at fixed size, the dependence on stellar mass is weak. Larger quiescent galaxies are marginally younger, quenched more slowly, and have near-solar metallicities, while compact quiescent galaxies are older, metal-rich, and quenched faster. PSBs formed half their mass later ($z_\rm{form}\sim1.9$) and quenched on the shortest timescales. The general trends with galaxy size, $Z_\star$, and $z_\rm{form}$ for the quiescent populations remain consistent regardless of the method used to derive the stellar properties. We conclude that compact quiescent galaxies are consistent with both early, moderately fast quenching and with more rapid, late quenching. While this may suggest the existence of multiple quenching channels, our data are also compatible with a continuous distribution of quenching timescales. These findings suggest that different physical mechanisms may drive quenching across galaxy populations, potentially leading to similar morphological outcomes despite differing evolutionary histories. - oai:arXiv.org:2512.10383v1 + LSTM-MDNz: Estimating Quasar Photometric Redshifts with an LSTM-Augmented Mixture Density Network + https://arxiv.org/abs/2512.16010 + arXiv:2512.16010v1 Announce Type: new +Abstract: Quasar photometric redshifts are essential for studying cosmology and large-scale structures. However, their complex spectral energy distributions cause significant redshift-color degeneracy, limiting the accuracy of traditional methods. To overcome this, we introduce LSTM-MDNz, a novel end-to-end deep learning model combining long short-term memory networks (LSTM) with mixture density networks (MDN). The model directly uses multi-band photometric fluxes and associated errors as wavelength-ordered sequential inputs, eliminating the need for manual feature engineering while enabling simultaneous point estimation and probability distribution function (PDF) prediction of quasar redshifts. We integrate data from four major sky surveys-SDSS, DESI-LS, WISE, and GALEX-to assemble a sample of over 550,000 spectroscopically confirmed quasars ($0 \leq z_{\mathrm{spec}} \leq 5$) across 14 ultraviolet to infrared bands for model training and testing. Experimental results show that using all 14 bands yields optimal performance, with a normalized median absolute deviation ($\sigma_{\mathrm{NMAD}}$) of 0.037 and an outlier rate ($f_{\mathrm{out}}$) of 3.5\% on the test set. These values represent reductions of 29\% and 56\%, respectively, compared to the commonly adopted SDSS+WISE band set. Probability integral transform ($\mathrm{PIT}$) and continuous ranked probability score ($\mathrm{CRPS}$) analyses confirm that the predicted PDFs align closely with the true redshift distribution. Band-ablation experiments further highlight the essential role of ultraviolet and infrared data in alleviating color degeneracy and reducing systematic bias. This study demonstrates the effectiveness of multi-band fusion in improving quasar photo-z accuracy and offers a ready-to-use estimation framework for future surveys like LSST, CSST, and Euclid. + oai:arXiv.org:2512.16010v1 astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.IM + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Angelos Nersesian, Yasha Kaushal, Marco Martorano, Arjen van der Wel, Po-Feng Wu, Rachel Bezanson, Eric F. Bell, Francesco D'Eugenio, Anna R. Gallazzi, Joel Leja, Stefano Zibetti, Sandro Tacchella + http://creativecommons.org/licenses/by/4.0/ + Jianzhen Chen, Zhijian Luo, Liping Fu, Zhu Chen, Hubing Xiao, Shaohua Zhang, Chenggang Shu - A Systematic Study of Magnetic Fields Impacts on Neutrino Transport in Core-Collapse Supernovae - https://arxiv.org/abs/2512.10417 - arXiv:2512.10417v1 Announce Type: new -Abstract: We quantify the impact of strong magnetic fields (assuming $B=B_0\cdot r_0^3/r^3$ with $B_0\gtrsim 10^{16}$ G) on the neutrino transport in core-collapse supernovae (CCSNe). Magnetic fields quantize the momenta of electrons and positrons, resulting in an enhanced absorption cross section for low-energy neutrinos and suppressed chemical potentials for $e^\pm$. We include these changes in the M1 scheme for neutrino transport and perform 1-D CCSNe simulations with \texttt{GR1D}. The increased low-energy cross sections reduce the $\bar{\nu}_e$ mean energy $\langle E_{\bar\nu_e}\rangle$ while elevating the neutrino number luminosities $\mathcal{L_\nu}$ for both ${\nu}_e$ and $\bar{\nu}_e$ due to the lower energy weighted spectra. The reduction of chemical potential enhances the $\bar{\nu}_e$ emission while suppressing that of $\nu_e$, thereby driving an increase in the electron fraction behind the stalled shock at $\sim30$--$100$ km. This further amplifies $\langle E_{\nu_e}\rangle$ through an increased electron density. Consequently, magnetic fields amplify $L_{\nu_e}$ by increasing both $\mathcal{L}_{\nu_e}$ and $\langle E_{\nu_e}\rangle$ whereas for $\bar\nu_e$, the rise in $\mathcal{L}_{\bar\nu_e}$ is offset by a decreased $\langle E_{\bar\nu_e}\rangle$, leading to a minimal change in $L_{\bar\nu_e}$. A systematic parameter scan of dipole field configurations suggests that, for $r_0 > 30$ km, $\langle E_{\bar{\nu}_e} \rangle$ is significantly suppressed and $L_{\nu_e}$ is enhanced if $B_0 \geq {2.7} \times 10^{16}$ G. These magnetic effects become negligible for $B_0$ below $\sim {7.4} \times 10^{15}$ G. - oai:arXiv.org:2512.10417v1 - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Direct calculation of steady-state hydrodynamic solar wind solutions with newtonian viscosity + https://arxiv.org/abs/2512.16028 + arXiv:2512.16028v1 Announce Type: new +Abstract: Steady-state solutions to the Navier-Stokes equations are known to admit solutions that are singular at the sonic point. Consequently, inviscid solar wind models require special treatment of the solution near the sonic points, and this has proven to be a significant impediment to efficient modeling of the solar wind. In this paper we revisit the governing hydrodynamic equations for the expanding solar wind, with the inclusion of the classical (Newtonian) viscous stress , and we show how this inclusion eliminates the singularities that emerge from the inviscid equations. This result has been previously reported and used to generate solar wind profiles from initial conditions in the asymptotic limit; however, those studies did not include realistic treatments of the inner corona, and generally rejected the prospect of extrapolating solutions outward from the Sun into the heliosphere. Here, we expand this method to include external heating and optically thin radiative losses and show that solutions can be computed from initial conditions near the solar surface, thereby capturing the entire range of scales from below the transition region to the outer heliosphere in a single solution. Our approach is to cast the steady-state Navier-Stokes equations as a system of five coupled, ordinary differential equations (ODEs), which we solve using conventional methods, without any special treatment of the governing equations in the vicinity of the sonic point. The representative solutions that we present here demonstrate the utility and efficiency of this extrapolation method, which is considerably more realistic than commonly used analytical or empirical models. This method provides a direct approach to generating accurate solar wind profiles subject to observationally motivated initial conditions near the solar surface, at a fraction of the computational cost of comparable relaxation-based models. + oai:arXiv.org:2512.16028v1 + astro-ph.SR + physics.flu-dyn + physics.plasm-ph + physics.space-ph + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yudong Luo, Shuai Zha, Toshitaka Kajino + 10.1051/0004-6361/202555327 + Roger B. Scott, Stephen J. Bradshaw, Mark G. Linton, Chris Lowder, Leonard Strachan - Detailed theoretical analysis of core Helium-burning stars: Mixed mode patterns I. Impact of the He-flash discontinuity and of induced semi-convection - https://arxiv.org/abs/2512.10474 - arXiv:2512.10474v1 Announce Type: new -Abstract: Space missions like CoRoT, Kepler, and TESS have made asteroseismology a powerful probe of stellar interiors. Red giants are key targets thanks to their rich mixed-mode oscillation spectra, which reveal properties of both core and envelope. However, current models of core helium-burning red giants still fail to fully reproduce observed oscillation patterns, largely due to uncertainties in mixing processes such as overshooting and semi-convection. This motivates the need for better seismic constraints to refine stellar models. We investigate how internal structural features shape asteroseismic signatures in core helium-burning stars, focusing on the links between seismic properties and internal chemical profiles. Using an updated version of the Liege stellar evolution code and its adiabatic oscillation code, we compute and analyse mixed-mode patterns for a range of stellar models. Our results show that sharp chemical gradients and central overshooting strongly influence the mixed-mode spectra. Changes in overshooting modify the extent of the semi-convective region, altering the local Brunt-Vaisala frequency and thus the observed period spacing. Variations in overshooting are compensated by shifts in semi-convective layers, keeping the total mixed-core size nearly constant across models. As a result, stellar evolution is only mildly affected, while the seismic signatures, especially the Brunt-Vaisala frequency profile, are highly sensitive to these internal adjustments. - oai:arXiv.org:2512.10474v1 + Astrometric and Spectroscopic Analysis of IC 2714: An Open Cluster Hosting a Lithium-Rich Giant + https://arxiv.org/abs/2512.16042 + arXiv:2512.16042v1 Announce Type: new +Abstract: Open clusters serve as laboratories to study and evaluate stellar evolution and Galactic chemical evolution models. Chemical peculiarities, such as lithium-rich giants, are rarely observed in these stellar systems. This work focuses on eight red giants (#005, #028, #034, #053, #087, #121, #126, and #190) previously reported as members of the Galactic cluster IC 2714. We conducted a detailed investigation using high-resolution spectroscopy, supplemented with data from the Gaia DR3 catalog. Besides deriving the cluster's fundamental parameters, we provide the most thorough chemical characterization of IC 2714 to date, reporting the abundance of 23 species, including light elements (Li, C, N, O), odd-Z elements (Na, Al), $\alpha$-elements (Si, Ca, Ti, Mg), iron-peak elements (Sc, Cr, Ni), $\textit{s}$-process-dominated elements (Y, Zr, Ba, La, Ce, Nd) and $\textit{r}$-process elements (Sm, Eu). We also present the carbon isotopic ratios $^{12}$C/$^{13}$C for the first time for seven stars. One particular star (#087) exhibits a high lithium abundance ($\log \varepsilon$(Li)$_{\rm NLTE}$ = $+$1.54 dex) and a slightly higher projected rotational velocity ($v \sin i$ = 6.7 km s$^{-1}$). Our results suggest that the analyzed stars are in the core-helium-burning phase of evolution, where the most lithium-rich giants are found. Combining astrometric probabilities and chemical abundances, we conclude that two giants (#028 and #034) might not be cluster members. + oai:arXiv.org:2512.16042v1 + astro-ph.GA astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 10.1051/0004-6361/202555524 - A&A Volume 704, December 2025, article number A22 - L. Panier, G. Buldgen, M. Matteuzzi, R. Scuflaire, M. A. Dupret, A. Noels, A. Miglio + 10.3847/1538-4357/ae2854 + T. Flaulhabe, N. Holanda, G. Tautvai\v{s}ien\.e, O. J. Katime Santrich, F. F. S. Maia, B. P. L. Ferreira, W. J. B. Corradi, C. B. Pereira, M. Carlos, S. Daflon - Multi-wavelength emission in resistive pulsar magnetospheres - https://arxiv.org/abs/2512.10479 - arXiv:2512.10479v1 Announce Type: new -Abstract: In this paper, we compute a full set of neutron star magnetosphere structures from the basic vacuum regime to the dissipation-less force-free regime by implementing a resistive prescription for the plasma. A comparison to the radiation reaction limit is also discussed. We investigated the impact of these resistive magnetospheres onto the multi-wavelength emission properties based on the polar cap model for radio wavelengths, on the slot gap model for X-rays and on the striped wind model for $\gamma$-rays.} % methods heading (mandatory) {We performed time-dependent pseudo-spectral simulations of the full Maxwell equations including a resistive Ohm's law. We deduced the polar cap shape and size, the Poynting flux, the magnetic field structure and the current sheet surface, depending on the magnetic obliquity~$\chi$ and on the conductivity~$\sigma$. We found that the geometry of the magnetosphere close to the stellar surface is not impacted by the amount of resistivity. Polar cap rims remain very similar in shape and size. However the Poynting flux varies significantly as well as the magnetic field sweep-back in the vicinity of the light-cylinder. This bending of field lines reflects into the $\gamma$-ray pulse profiles, changing the $\gamma$-ray peak separation~$\Delta$ as well as the time lag~$\delta$ between the radio pulse and $\gamma$-ray peaks. X-ray pulse profiles are also drastically affected by the resistivity. A full set of multi-wavelength light-curves can be compiled for future comparison with the third $\gamma$-ray pulsar catalogue. This systematic study will help to constrain the amount of magnetic energy flowing into particle kinetic energy and shared by radiation. - oai:arXiv.org:2512.10479v1 + Gas Accretion from a Neighbouring Galaxy Fuels the Low-luminosity AGN in NGC 4278 + https://arxiv.org/abs/2512.16049 + arXiv:2512.16049v1 Announce Type: new +Abstract: How a seemingly `dead' host galaxy provides fuel for its active galactic nuclei (AGN) remains an unresolved problem. Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we present a new high-sensitivity atomic-hydrogen (HI) observation toward the nearby elliptical galaxy NGC 4278 and its adjacent region. From the observation, we found that external gas accretion from a neighbouring galaxy fuels the low-luminosity AGN in NGC 4278 through tidal interactions. The accreted gas entering NGC 4278 exhibits a rotating gas disk. And the accreted galaxy has been gas-poor and has an HI to stellar mass ratio of about 0.02. Due to the process of gas accretion, it is likely that relativistic jets are generated in the AGN of NGC 4278. The emission of TeV gamma rays in NGC 4278 is likely to be associated with the newly accreted HI gas. + oai:arXiv.org:2512.16049v1 + astro-ph.GA astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - J\'er\^ome P\'etri + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Jin-Long Xu, Nai-Ping Yu, Ming Zhu, Chuan-Peng Zhang, Xiao-Lan Liu, Mei Ai, Peng Jiang - FAUST XXX: Dust enhancement in the young binary L1551 IRS 5 - https://arxiv.org/abs/2512.10486 - arXiv:2512.10486v1 Announce Type: new -Abstract: Young binary stars with discs provide unique laboratories to study the earliest stages of planet formation in star-forming environments. The detection of substructure in discs around Class I protostars challenges current models of disc evolution, suggesting that planets may form earlier than previously expected ($<1$ Myr). In the context of the ALMA Large Program FAUST, we present observations of the circumbinary disc (CBD) around the young binary system L1551 IRS 5. The CBD exhibits two prominent over-densities in the continuum emission at the edge of the cavity, with the Northern over-density being about 20% brighter than the Southern one. By analysing the disc morphology and kinematics of L1551 IRS 5, we delineate dynamical constraints on the binary's orbital parameters. Additionally, we present 3D hydrodynamical models of the CBD to predict both the dust and the gas surface densities. Then, we compare the resulting synthetic observations with ALMA observations of the continuum emission at 1.3 mm and the C$^{18}$O line emission. Our analysis suggests that the density enhancements observed with ALMA in L1551 IRS 5 can be caused by interactions between the binary stars and the CBD, leading to dust concentration within the disc. We conclude that the observed over-density corresponds to a location where could potentially grow under favourable conditions. - oai:arXiv.org:2512.10486v1 - astro-ph.SR + Graph Neural Networks for Interferometer Simulations + https://arxiv.org/abs/2512.16051 + arXiv:2512.16051v1 Announce Type: new +Abstract: In recent years, graph neural networks (GNNs) have shown tremendous promise in solving problems in high energy physics, materials science, and fluid dynamics. In this work, we introduce a new application for GNNs in the physical sciences: instrumentation design. As a case study, we apply GNNs to simulate models of the Laser Interferometer Gravitational-Wave Observatory (LIGO) and show that they are capable of accurately capturing the complex optical physics at play, while achieving runtimes 815 times faster than state of the art simulation packages. We discuss the unique challenges this problem provides for machine learning models. In addition, we provide a dataset of high-fidelity optical physics simulations for three interferometer topologies, which can be used as a benchmarking suite for future work in this direction. + oai:arXiv.org:2512.16051v1 + astro-ph.IM + cs.LG + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by-sa/4.0/ + Sidharth Kannan, Pooyan Goodarzi, Evangelos E. Papalexakis, Jonathan W. Richardson + + + Axisymmetric Modeling of DSHARP Dusty Disks: Asymmetric Structures and Inner-Disk Dispersal + https://arxiv.org/abs/2512.16091 + arXiv:2512.16091v1 Announce Type: new +Abstract: High-resolution observations of Class II protoplanetary disks frequently reveal annular structures that may indicate the presence of embedded planets. In this study, we model brightness profiles and geometries for 16 dusty disks in the DSHARP observations to identify asymmetric substructures, including possible planet-induced signatures. We find no compelling evidence for circumplanetary emission in these systems. We identify a possible one-armed spiral in Elias 27; while previous studies report an $m=2$ spiral, the morphology of the newly identified spiral agrees with a spiral for a possible protoplanet. Although non-detection of circumplanetary emission is consistent with low expected luminosities, the absence of additional dust spirals except for Elias 27 may constrain properties of potential embedded planets given their theoretical detectability. The analyses further suggest that spiral amplitudes and phases correlated with gap and ring locations in WaOph 6 and IM Lup, appearing as deflections of spirals in images. Five disks exhibit strong residual asymmetries attributable to the vertical extent of their dust layers. We find that the brightness temperature of inner disks ($1$-$5$ au) declines with stellar age on a $\sim 3$ Myr timescale, while the total flux shows no clear decreasing trend. This trend is consistent with the presence of pressure bumps that retain large dust grains at outer radii, while allowing the inner disks to disperse. The universality of disk dispersal timescale at millimeter wavelengths, observed in both the extended DSHARP disks and the compact disks from previous demographic surveys, may constrain timing of planet formation, including habitable planets. + oai:arXiv.org:2512.16091v1 astro-ph.EP - astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Nicol\'as Cuello, Eleonora Bianchi, Fran\c{c}ois M\'enard, Laurent Loinard, Ricardo Hern\'andez Garnica, Aurora Dur\'an, Cecilia Ceccarelli, Mar\'ia Jos\'e Maureira, Claire J. Chandler, Claudio Codella, Nami Sakai, Linda Podio, Giovanni Sabatini, Layal Chahine, Marta de Simone, Davide Fedele, Doug Johnstone, Tomoyuki Hanawa, Izaskun Jim\'enez-Serra, Satoshi Yamamoto + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Masataka Aizawa, Takayuki Muto, Munetake Momose - Scintillating insights into PSR~J0737$-$3039A and the interstellar plasma of the Gum Nebula from MeerKAT - https://arxiv.org/abs/2512.10489 - arXiv:2512.10489v1 Announce Type: new -Abstract: The double pulsar system PSR~J0737$-$3039A/B has enabled some of the most precise tests of strong-field gravity to date. Here, we present a scintillation analysis of the system based on an 18-month observation campaign with the MeerKAT radio telescope. We characterise this interference pattern to infer properties of scattering plasma and the orbital geometry of the system. Our preferred model supports a scattering screen located at a distance of $D_s = 360^{+30}_{-40}$ pc. This moderately anisotropic screen of ionized gas (axial ratio $A_R = 2.4 \pm 0.2$) lies near the edge of the Gum Nebula, which is believed to be a supernova remnant (SNR) or an \HII\, region. We estimate the expansion velocity of the nebula to be $V_{\textrm{s}} = 35 \pm 5$ km s$^{-1}$, implying a SNR age of $t \approx 1$ Myr. We also constrain the orbital orientation and inclination sense of the double pulsar to be $\Omega = 40^{\circ} \pm 3^{\circ}$ and $i > 90^{\circ}$, respectively. Assuming standard scattering geometry, our model yields a distance estimate consistent with the parallax-derived value of $D = 770 \pm 70$ pc from very long baseline interferometry. We conclude by discussing how future models of pulsar scintillation can enhance our understanding of the IISM and the properties of pulsars embedded within or lying behind such intervening structures. - oai:arXiv.org:2512.10489v1 + Inferring the Intrinsic Energy Function of FRB 20220912A + https://arxiv.org/abs/2512.16122 + arXiv:2512.16122v1 Announce Type: new +Abstract: The statistical analysis of fast radio burst (FRB) samples from repeaters may suffer from a band-limited selection effect, which can bias the observed distribution. We investigated the impact of this selection bias on the energy function through simulations and then applied our analysis to the particular case of FRB 20220912A. Our simulations show that, in the sample of bursts observed by the Five hundred meter Aperture Spherical Telescope (FAST), assuming a unimodal intrinsic energy distribution, the band selection effect alone is insufficient to produce a bimodal energy distribution; only the bimodal central frequency distribution can achieve this. The bursts' energy of FRB 20220912A that primarily fell within the observing band showed no significant correlation with the central frequency. In contrast, bursts with higher central frequency tend to exhibit narrower bandwidth and longer duration. The distribution of the intrinsic energy can be modeled as a log-normal distribution with a characteristic energy of $8.13 \times 10^{37}$ erg, and a power-law function with the index of $1.011 \pm 0.028$. In contrast to the initial energy function reported by \cite{2023ApJ...955..142Z}, the low-energy peak vanishes, and the high-energy decline becomes steeper, which implies the low-energy peak is an observational effect. The bimodality of the energy distribution seems to originate from the intrinsic radiation mechanism. + oai:arXiv.org:2512.16122v1 astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/publicdomain/zero/1.0/ - J. Askew, D. J. Reardon, R. M. Shannon, M. Bailes, F. Camilo, A. Corongiu, M. Kramer, M. E. Lower, A. Parthasarathy, A. Possenti, V. Venkatraman Krishnan + http://creativecommons.org/licenses/by/4.0/ + Xiaohui Liu, Wei-Yang Wang, Weicong Jing, Xuelei Chen, Jinlin Han - Does the Babcock-Leighton dynamo operate in rapidly rotating solar-type stars? Exploration using a 3D dynamo model at different rotation rates - https://arxiv.org/abs/2512.10508 - arXiv:2512.10508v1 Announce Type: new -Abstract: The Babcock-Leighton dynamo, which relies on the generation of a poloidal field through the decay and dispersal of tilted bipolar magnetic regions (BMRs), is a promising paradigm for explaining the features of the solar magnetic cycle. In rapidly rotating stars, BMRs are expected to emerge at high latitudes, which are less efficient in generating the poloidal field due to poor cross-equatorial cancellation. The operation of the Babcock-Leighton dynamo in rapidly rotating stars is therefore questionable. We, for the first time, using a 3D kinematic dynamo model, STABLE, explore this question. By taking large-scale flows from mean-field hydrodynamics models for stars rotating at different speeds, We conduct a series of dynamo simulations in rapidly rotating stars, exploring the following four cases of spot deposition, each based on a different assumption about toroidal flux tube rise: (i) radial rise, (ii) parallel rise to the rotation axis, (iii) parallel rise combined with an increase in Joy's law slope with the stellar rotation rate, and (iv) increasing time delay and spot size. We find cyclic magnetic fields in all cases except case IV of the 1-day rotating star, for which the magnetic field is irregular. For the parallel-rise cases, the magnetic field becomes quadrupolar, and for all other cases, it is dipolar. Our work demonstrates that the Babcock-Leighton dynamo may operate even in rapidly rotating stars with starspots appearing at higher latitudes. - oai:arXiv.org:2512.10508v1 - astro-ph.SR + Pulsar Science with the SKA Observatory + https://arxiv.org/abs/2512.16152 + arXiv:2512.16152v1 Announce Type: new +Abstract: The large instantaneous sensitivity, a wide frequency coverage and flexible observation modes with large number of beams in the sky are the main features of the SKA observatory's two telescopes, the SKA-Low and the SKA-Mid, which are located on two different continents. Owing to these capabilities, the SKAO telescopes are going to be a game-changer for radio astronomy in general and pulsar astronomy in particular. The eleven articles in this special issue on pulsar science with the SKA Observatory describe its impact on different areas of pulsar science. In this lead article, a brief description of the two telescopes highlighting the relevant features for pulsar science is presented followed by an overview of each accompanying article, exploring the inter-relationship between different pulsar science use cases. + oai:arXiv.org:2512.16152v1 + astro-ph.HE astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Vindya Vashishth, Bidya Binay Karak + http://creativecommons.org/licenses/by/4.0/ + Bhal Chandra Joshi, Aris Karastergiou, Marta Burgay, The SKA pulsar science working group - Isotopomer-Specific Carbon Isotope Ratio of Complex Organic Molecules in Star-Forming Cores - https://arxiv.org/abs/2512.10516 - arXiv:2512.10516v1 Announce Type: new -Abstract: Recent high-resolution and sensitivity ALMA observations have unveiled the carbon isotope ratios ($^{12}$C/$^{13}$C) of Complex Organic Molecules (COMs) in a low-mass protostellar source. To understand the $^{12}$C/$^{13}$C ratios of COMs, we investigated the carbon isotope fractionation of COMs from prestellar cores to protostellar cores with a gas-grain chemical network model. We confirmed that the $^{12}$C/$^{13}$C ratios of small molecules are bimodal in the prestellar phase: CO and species formed from CO (e.g., CH$_{3}$OH) are slightly enriched in $^{13}$C compared to the local ISM (by $\sim$ 10 $\%$), while those from C and C$^{+}$ are depleted in $^{13}$C owing to isotope exchange reactions. COMs are mainly formed on the grain surface and in the hot gas ($>$ 100 K) in the protostellar phase. The $^{12}$C/$^{13}$C ratios of COMs depend on which molecules the COMs are formed from. In our base model, some COMs in the hot gas are depleted in $^{13}$C compared to the observations. Thus, We additionally incorporate reactions between gaseous atomic C and H$_{2}$O ice or CO ice on the grain surface to form H$_2$CO ice or \ce{C2O} ice, as suggested by recent laboratory studies. The direct C-atom addition reactions open pathways to form \ce{^13C}-enriched COMs from atomic C and CO ice. We find that these direct C-atom addition reactions mitigate $^{13}$C-depletion of COMs, and the model with the direct C-atom addition reactions better reproduces the observations than our base model. We also discuss the impact of the cosmic ray ionization rate on the $^{12}$C/$^{13}$C ratio of COMs. - oai:arXiv.org:2512.10516v1 + A Square Kilometre Array Pulsar Census + https://arxiv.org/abs/2512.16153 + arXiv:2512.16153v1 Announce Type: new +Abstract: Most of the pulsar science case with the Square Kilometre Array (SKA) depends on long-term precision pulsar timing of a large number of pulsars, as well as astrometric measurements of these using very long baseline interferometry (VLBI). But before we can time them, or VLBI them, we must first find them. Here, we describe the considerations and strategies one needs to account for when planning an all-sky blind pulsar survey using the SKA. Based on our understanding of the pulsar population, the performance of the now-under-construction SKA elements, and practical constraints such as evading radio frequency interference, we project pulsar survey yields using two complementary methods for a number of illustrative survey designs, combining SKA1-Low and SKA1-Mid Bands 1 and 2 in a variety of ways. A composite survey using both Mid and Low is optimal, with Mid Band 2 focused in the plane. We find that, given its much higher effective area and survey speed, the best strategy is to use SKA1-Low to cover as much sky as possible, ideally also overlapping with the areas covered by Mid. In our most realistic scenario, we find that an all-sky blind survey with Phase 1 of the SKA with the AA* array assembly will detect $\sim10,000$ slow pulsars and $\sim 800$ millisecond pulsars (MSPs) if SKA1-Mid covers the region within $5\deg$ of the plane, while higher latitudes will be covered with SKA1-Low. The yield with AA4 is $\sim 20\%$ higher. One could increase these numbers by increasing the range covered by SKA1-Mid Bands 1 and 2, at the cost of a considerably longer survey. The pulsar census will enable us to set new constraints on the uncertain physical properties of the entire neutron star population. This will be crucial for addressing major SKA science questions including the dense-matter equation of state, strong-field gravity tests, and gravitational wave astronomy. + oai:arXiv.org:2512.16153v1 + astro-ph.HE astro-ph.GA + astro-ph.IM astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1021/acsearthspacechem.5c00180 - Ryota Ichimura, Hideko Nomura, Kenji Furuya, Tetsuya Hama, T. J. Millar + http://creativecommons.org/licenses/by/4.0/ + E. F. Keane, V. Graber, L. Levin, C. M. Tan, O. A. Johnson, C. Ng, C. Pardo-Araujo, M. Ronchi, D. Vohl, M. Xue, The SKA Pulsar Science Working Group - The SALT survey of helium-rich hot subdwarfs: final sample and classification - https://arxiv.org/abs/2512.10529 - arXiv:2512.10529v1 Announce Type: new -Abstract: A medium-resolution spectroscopic survey of helium-rich hot subdwarfs has been carried out using the Southern African Large Telescope (SALT). Objectives include the discovery of exotic hot subdwarfs, resolving distinct subclasses, identifying evolutionary sequences, and establishing the past and future histories of many of these unusual stars. This paper extends the sample described by Jeffery et al. (2021) (arXiv:2011.09523) from 100 to 697 stars. It describes the selection criteria and presents spectral classifications based on the MK-like Drilling system. The sample includes 283 extremely helium-rich hot subdwarfs, 17 extreme helium stars, 110 intermediate helium-rich hot subdwarfs, as well as 21 helium-rich stars of other types. It now represents the largest homogeneous sample of both "normal" He-sdOs and "luminous" or "hot" He-sdOs. Interesting stars discovered include magnetic hot subdwarfs, extremely hot pre-white dwarfs and hot subdwarfs, including hot subdwarfs showing NV emission, one short-period binary, new extreme helium stars and several double-subdwarf candidates. The data form the basis for kinematic and model atmosphere analyses to follow. - oai:arXiv.org:2512.10529v1 + Pulsars in Globular Clusters With the SKAO + https://arxiv.org/abs/2512.16154 + arXiv:2512.16154v1 Announce Type: new +Abstract: Because of their extreme stellar densities, globular clusters are highly efficient factories of X-ray binaries and radio pulsars: per unit of stellar mass, they contain about 1000 times more of these exotic objects. Thus far, 345 radio pulsars have been found in globular clusters. These can be used as precision probes of the structure, gas content, magnetic field, and dynamic history of their host clusters; some of them are also highly interesting in their own right because they probe exotic stellar evolution scenarios as well as the physics of dense matter, accretion, and gravity; one of them (PSR~J0514$-$4002E) might even be the first pulsar - black hole system known. Deep searches with SKA-MID and SKA-LOW will only require one to a few tied-array beams, and can be done during early commissioning of the telescope, before an all-sky pulsar survey using hundreds to thousands of tied-array beams is feasible. Even a conservative approach predicts new discoveries only with the core of SKA-MID AA*, and the full AA* and eventually AA4 is expected to increase the number of discoveries even more, leading to more than doubling the current known population. This offers a great opportunity for early SKAO pulsar science, even before all the collecting area is in place. On the other hand, a more optimistic prediction calls for a 4-5 times growth of the population, leading to a total of about 1700 pulsars to be detectable with SKA-MID AA4 configuration in all Galactic GCs visible by SKA telescopes. Thus, a dedicated search for pulsars in globular clusters will fully exploit the best possible natural laboratories to study many branches of physics and astrophysics, including properties of dense matter, stellar evolution, and the dynamical history of the Galactic globular cluster systems. + oai:arXiv.org:2512.16154v1 + astro-ph.HE + astro-ph.GA astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - C. Simon Jeffery, Matti Dorsch, Asish Philip Monai, Edward J. Snowdon, Itumaleng Monageng, Brent Miszalski + http://creativecommons.org/licenses/by/4.0/ + Manjari Bagchi, Federico Abbate, Vishnu Balakrishnan, Miquel Colom i Bernadich, Bhaswati Bhattacharyya, Arunima Dutta, Paulo C. C. Freire, Kriisa Halley, Jason W. T. Hessels, Sangeeta Kumari, Duncan R. Lorimer, Andrea Possenti, Rouhin Nag, Scott M. Ransom, Alessandro Ridolfi, Vivek Venkatraman Krishnan, Weiwei Zhu, The SKA Pulsar Science Working Group - Application of time-series analysis methods to a multiple-sector TESS observations: the case of the radio-loud blazar 3C 371 - https://arxiv.org/abs/2512.10533 - arXiv:2512.10533v1 Announce Type: new -Abstract: We present various time series analysis methods to analyze multiple-sector observations of bright AGN from the Transiting Exoplanet Survey Satellite (TESS) and examine whether issues such as gaps and noise in these data can be mitigated. We determine variability timescales and search for quasi-periodicity using these methods and assess any differences. In this paper, we present an analysis of the $\approx$300-day TESS observation of a blazar 3C 371 using power spectrum density, structure-function, and weighted wavelet Z-transform approaches. To reduce the effect of gaps and noise, Continuous auto-regressive moving averages, Bartlett periodogram, and wavelet decomposition methods are used. We have also used recurrence analysis to account for the nonlinearity present in the data and to quantify variability or periodicity as the recurrent state. Considering the entirety of the TESS observations, we derive the variability timescale to be around 4.5 days. Sector-wise analysis found variability timescales in the range of 3.0--7.0 days, values that are found to be consistent using different methods. When analyzing multiple sectors together, significant variability, which could be quasi-periodic oscillations (QPOs), of duration 3--6 days in individual segments, is detected. These may be attributed to the kink instabilities developed in the jet or the existence of mini-jets inside a jet undergoing precession. We find that these methods, when applied appropriately, can be used to study the variability in TESS data. The noise present in these TESS observations can be minimized using Bartlett's periodogram and wavelet decomposition to recover the real stochastic variability. - oai:arXiv.org:2512.10533v1 + Galactic Centre Pulsars with the SKAO + https://arxiv.org/abs/2512.16155 + arXiv:2512.16155v1 Announce Type: new +Abstract: The detection of a pulsar closely orbiting our Galaxy's supermassive black hole - Sagittarius A* - is one of the ultimate prizes in pulsar astrophysics. The relativistic effects expected in such a system could far exceed those currently observable in compact binaries such as double neutron stars and pulsar white dwarfs. In addition, pulsars offer the opportunity to study the magneto-ionic properties of Earth's nearest galactic nucleus in unprecedented detail. For these reasons, and more, a multitude of pulsar searches of the Galactic Centre have been undertaken, with the outcome of just seven pulsar detections within a projected distance of 100 pc from Sagittarius A*. It is currently understood that a larger underlying population likely exists, but it is not until observations with the SKA have started that this population can be revealed. In this paper, we look at important updates since the publication of the last SKAO science book and offer a focused view of observing strategies and likely outcomes with the updated SKAO design. + oai:arXiv.org:2512.16155v1 astro-ph.HE - hep-ph - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 10.1093/mnras/staf1920 - Ashutosh Tripathi, Paul J. Wiita, Ryne Dingler, Krista Lynne Smith, R. A. Phillipson, Matthew J. Graham, Lang Cui + F. Abbate, A. Carleo, S. Chatterjee, J. Cordes, P. B. Demorest, G. Desvignes, R. P. Eatough, E. Hackmann, Hu Z., M. Kramer, J. Lazio, K. J. Lee, K. Liu, I. Rammala-Zitha, S. M. Ransom, G. Saowanit, L. Shao, P. Torne, R. Wharton, J. Wongphechauxsorn, W. Zhu, The SKAO Pulsar Science Working Group - Near Ultraviolet Transient Explorer (NUTEx): A CubeSat-Based NUV Imaging Payload for Transient Sky Surveys - https://arxiv.org/abs/2512.10538 - arXiv:2512.10538v1 Announce Type: new -Abstract: The Near Ultraviolet Transient Explorer (NUTEx) is a CubeSat-based near-ultraviolet (NUV) imaging payload designed for transient sky surveys and is currently under development. CubeSats are compact and cost-effective satellite platforms that have emerged as versatile tools for scientific exploration and technology demonstrations in space. NUTEx is an imaging telescope operating in the 200-300 nm wavelength range, intended for deployment on a micro-satellite bus. The optical system is based on a Ritchey Chretien (RC) telescope configuration, featuring a 146 mm primary mirror. The detector is a photon-counting microchannel plate (MCP) device with a solar-blind photocathode, paired with an in-house developed readout unit. The instrument has a wide field of view (FoV) of 4 deg, a peak effective area of approximately 18 sq cm at 260 nm, and can reach a sensitivity of 21 AB magnitude (SNR = 5) in a 200 second exposure. The primary scientific objective of NUTEx is to monitor the night sky for transient phenomena, such as supernova remnants, flaring M-dwarf stars, and other short-timescale events. The payload is currently scheduled for launch in Q2 2026. This paper presents the NUTEx instrument design, outlines its scientific goals and capabilities, and provides an overview of the electronics and mechanical subsystems, including structural analysis. - oai:arXiv.org:2512.10538v1 + Understanding the Neutron Star Population with the SKAO telescopes + https://arxiv.org/abs/2512.16156 + arXiv:2512.16156v1 Announce Type: new +Abstract: The known population of non-accreting neutron stars is ever growing and currently consists of more than 3500 sources. Pulsar surveys with the SKAO telescopes will greatly increase the known population, adding radio pulsars to every subgroup in the radio-loud neutron star family. These discoveries will not only add to the current understanding of neutron star physics by increasing the sample of sources that can be studied, but will undoubtedly also uncover previously unknown types of sources that will challenge our theories of a wide range of physical phenomena. A broad variety of scientific studies will be made possible by a significantly increased known population of neutron stars, unravelling questions such as: How do isolated pulsars evolve with time; What is the connection between magnetars, high B-field pulsars, and the newly discovered long-period pulsars; How is a pulsar's spin-down related to its radio emission; What is the nuclear equation of state? Increasing the known numbers of pulsars in binary or triple systems may enable both larger numbers and higher precision tests of gravitational theories and general relativity, as well as probing the neutron star mass distribution. The excellent sensitivity of the SKAO telescopes combined with the wide field of view, large numbers of simultaneous tied-array beams that will be searched in real time, wide range of observing frequencies, and the ability to form multiple sub-arrays will make the SKAO an excellent facility to undertake a wide range of neutron star research. In this paper, we give an overview of different types of neutron stars and discuss how the SKAO telescopes will aid in our understanding of the neutron star population. + oai:arXiv.org:2512.16156v1 + astro-ph.HE astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 10.3389/fspas.2025.1670437 - Shubham Ghatul, Rekhesh Mohan, Jayant Murthy, Margarita Safonova, Praveen Kumar, Maheswar Gopinathan, Shubhangi Jain, Mahesh Babu S + L. Levin, M. Bagchi, M. Burgay, A. T. Deller, V. Graber, A. Igoshev, M. Kramer, D. Lorimer, B. Posselt, T. Prabu, K. Rajwade, N. Rea, B. Stappers, T. M. Tauris, P. Weltevrede, The SKAO Pulsar Science Working Group - Stellar Evolution in Close Binaries: Processes and Outcomes - https://arxiv.org/abs/2512.10543 - arXiv:2512.10543v1 Announce Type: new -Abstract: We discuss some aspects of stellar evolution in binary systems. While single stars can swell following the chemical evolution of their interior, stars belonging to binary systems cannot overflow the size of the Roche lobe and hydrostatic equilibrium is strictly impossible. The system is forced to exchange mass between its members through the inner Lagrangian point. In the first part of the paper, we discuss the standard evolution of binaries that have a non-degenerate donor star and a compact companion. We show that the model fails when to account for the occurrence of binary pulsars when they predict a long-standing mass transfer episode. Models including irradiation feedback and evaporation in close binaries are examined next. Following these sections, we discuss the case of systems with a black hole (BH). We show that if BHs are born non-rotating, binary interaction seems insufficient to speed them up, an indication that BH rotation is a feature present at birth. Finally, we discuss Blue Straggler Stars detected in open and globular clusters. Since they cannot be understood as single-born stars, we evaluate one of the proposed channels is mass transfer in close binaries, and discuss its viability and the limitations of the present models. - oai:arXiv.org:2512.10543v1 - astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + Understanding pulsar magnetospheres with the SKAO + https://arxiv.org/abs/2512.16157 + arXiv:2512.16157v1 Announce Type: new +Abstract: The SKA telescopes will bring unparalleled sensitivity across a broad radio band, a wide field of view across the Southern sky, and the capacity for sub-arraying, all of which make them the ideal instruments for studying the pulsar magnetosphere. This paper describes the advances that have been made in pulsar magnetosphere physics over the last decade, and details how these have been made possible through the advances of modern radio telescopes, particularly SKA precursors and pathfinders. It explains how the SKA telescopes would transform the field of pulsar magnetosphere physics through a combination of large-scale monitoring surveys and in-depth follow-up observations of unique sources and new discoveries. Finally, it describes how the specific observing opportunities available with the AA* and AA4 configurations will achieve the advances necessary to solve the problem of pulsar radio emission physics in the coming years. + oai:arXiv.org:2512.16157v1 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 10.1002/asna.70034 - Astronomische Nachrichten, 2025. Volume 346, Issue 7-8, id.e70034, 11 pp - O. G. Benvenuto, M. A. De Vito, L. Bartolomeo Koninckx, M. Echeveste, M. L. Novarino, J. E. Horvath + L. S. Oswald, A. Basu, M. Chakraborty, B. C. Joshi, N. Lewandowska, K. Liu, M. E. Lower, A. Philippov, X. Song, P. Tarafdar, J. van Leeuwen, A. L. Watts, P. Weltevrede, G. Wright, J. Benacek, A. Beri, S. Cao, P. Esposito, F. Jankowski, J. C. Jiang, A. Karastergiou, K. J. Lee, N. Rea, D. Vohl, The SKA Pulsar Science Working Group - Wind-mediated Eddington-limited emission in a 1e4 Black Hole Tidal Disruption Event - https://arxiv.org/abs/2512.10564 - arXiv:2512.10564v1 Announce Type: new -Abstract: Observations of tidal disruption events (TDEs) have already produced tens of strong candidate flares, and their number will greatly increase with upcoming wide field surveys. Nevertheless, the origin of the measured luminosity peak at early times is still unknown, and the ultimate sources of energy dissipation in TDEs are not fully understood. Here we present the first three-dimensional end-to-end simulation of a TDE by a $10^{4}M_\odot$ intermediate mass black hole (IMBH) with realistic parameters, run with the radiation-hydrodynamics code RICH. We find that the stellar debris fails to circularize efficiently, while a low-density, radiation-driven wind forms near pericenter and expands quasi-spherically. Radiation is advected by this outflow and released at the photosphere, which expands to radii of $\approx10^{13}$ cm and reaches temperatures of ~few $10^{4}$K at the peak of the light curve. The resulting luminosity briefly exceeds the Eddington limit before settling near that value. We systematically test the numerical convergence of our simulation by running it at three resolutions. While the nozzle shock at pericenter may be under-resolved, we find that global results are qualitatively converged and, largely, quantitatively robust. The upcoming Vera Rubin Observatory's LSST (g and r band) and ULTRASAT (near UV) will be able to observe events like our simulated IMBH TDE up to redshifts of z$\approx$0.1 and z$\approx$0.06, respectively. - oai:arXiv.org:2512.10564v1 + Exploring Galactic plasma with pulsars in the SKA era + https://arxiv.org/abs/2512.16158 + arXiv:2512.16158v1 Announce Type: new +Abstract: The ionised media that permeate the Milky Way have been active topics of research since the discovery of pulsars in 1967. In fact, pulsars allow one to study several aspects of said plasma, such as their column density, turbulence, scattering measures, and discrete, intervening structures between the neutron star and the observer, as well as aspects of the magnetic field throughout. Such sources of information allow us to characterise the electron distribution in the terrestrial ionosphere, the Solar Wind, and our Galaxy, as well as the impact on other experiments involving pulsars, such as Pulsar Timing Arrays. In this article, we review the state-of-the-art in plasma research using pulsars, the aspects that should be taken into consideration for optimal plasma studies, and we provide future perspectives on improvements enabled by the SKA. + oai:arXiv.org:2512.16158v1 astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Paola Martire, Elena Maria Rossi, Nicholas Chamberlain Stone, Elad Steinberg, Konstantinos Kilmetis, Itai Linial + C. Tiburzi, M. T. Lam, D. J. Reardon, N. K. Porayko, M. Mevius, S. Koch Ocker, S. C. Susarla, J. R. Dawson, A. Deller, G. M. Shaifullah, M. Walker, W. Jing, F. A. Iraci, N. D. R. Bhat, M. Geyer, L. Levin, M. Keith - MAUVE-MUSE: A Star Formation-driven Outflow Caught in the Act of Quenching the Stripped Virgo Galaxy NGC 4064 - https://arxiv.org/abs/2512.10574 - arXiv:2512.10574v1 Announce Type: new -Abstract: The rapid quenching of satellite galaxies in dense environments is often attributed to environmental processes such as ram pressure stripping. However, stripping alone cannot fully account for the removal of dense, star-forming gas in many satellites, particularly in their inner regions. Recent models and indirect observations have suggested that star formation-driven outflows may play a critical role in expelling this remaining gas, yet direct evidence for such feedback-driven quenching remains limited. Here we report the discovery of an ionized gas outflow in NGC 4064, a Virgo cluster satellite that has already lost most of its cold gas through environmental stripping. MUSE observations from the Multiphase Astrophysics to Unveil the Virgo Environment (MAUVE) survey reveal a bi-polar outflow driven by residual, centrally concentrated star formation in NGC 4064 - despite its current star formation rate being ~0.4 dex below the star-forming main sequence due to prior interaction with the cluster environment. The outflow's mass loading factor is ~2, suggesting that stellar feedback could remove the remaining gas on timescales shorter than those required for depletion by star formation alone. These results demonstrate that even modest but centrally concentrated star formation can drive efficient feedback in stripped satellites, accelerating quenching in the final stages of their evolution. - oai:arXiv.org:2512.10574v1 + Exploring the magnetic field structure of the Milky Way with pulsars in the SKA era + https://arxiv.org/abs/2512.16159 + arXiv:2512.16159v1 Announce Type: new +Abstract: The magnetic field structure of the Milky Way can offer critical insights into the origin of galactic magnetic fields. Measurements of magnetic structures of the Milky Way are still sparse in far regions of the Galactic disk and halo. Pulsars are the best probes for the three-dimensional structure of the Galactic magnetic field, primarily owing to their highly polarized short-duration radio pulses, negligible intrinsic Faraday rotation compared to the contribution from the medium in front, and their widespread distribution throughout the Galaxy across the thin disk, spiral arms, and extended halo. In this article, we give an overview of Galactic magnetic field investigation using pulsars. The sensitive SKA1 design baseline (AA4) will increase the number of known pulsars by a factor of around three, and the initial staged delivery array (AA*) will probably double the total number of the current pulsar population. Polarization observations of pulsars with the AA* telescopes will give rotation measures along several thousand lines of sight, enabling detailed exploration of the magnetic structure of both the Galactic disk and the Galactic halo. + oai:arXiv.org:2512.16159v1 astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Amy Attwater, Barbara Catinella, Luca Cortese, Timothy Davis, Toby Brown, A. Fraser-McKelvie, Andrew Battisti, Alessandro Boselli, Pavel J\'achym, Andrei Ristea, Kristine Spekkens, Sabine Thater, Christine Wilson + Jun Xu, J. L. Han, Weicong Jing, The SKA Pulsar Science Working Group - An analytical framework for atmospheric tides on rocky planets. I. Formulation - https://arxiv.org/abs/2512.10578 - arXiv:2512.10578v1 Announce Type: new -Abstract: Atmospheric thermal tides arise from the diurnal contrast in stellar irradiation. They exert a significant influence on the long-term rotational evolution of rocky planets because they can accelerate the planetary spin, thereby counteracting the decelerating effect of classical gravitational tides. Consequently, equilibrium tide-locked states may emerge, as exemplified by Venus and hypothesised for Precambrian Earth. Quantifying the atmospheric thermal torque and elucidating its dependence on tidal frequency -- both in the low- and high-frequency regimes -- is therefore essential. In particular, we focus here on the resonance that affected early Earth, which is associated with a forced Lamb wave. Within the framework of linear theory, we develop a new analytical model of the atmospheric response to both gravitational an thermal tidal forcings for two representative vertical temperature profiles that bracket the atmospheres of rocky planets: (i) an isothermal profile (uniform temperature) and (ii) an isentropic profile (uniform potential temperature). Dissipative processes are incorporated via Newtonian cooling. We demonstrate that the isothermal and isentropic cases are governed by the same general closed-form solution, and we derive explicit expressions for the three-dimensional tidal fields (pressure, temperature, density and wind velocities) throughout the spherical atmospheric shell. These results constitute the foundation for two forthcoming papers, in which analytical formulae for the thermotidal torque will be presented and compared with numerical solutions obtained from General Circulation Models (GCMs). - oai:arXiv.org:2512.10578v1 - astro-ph.EP - physics.ao-ph - physics.geo-ph - Fri, 12 Dec 2025 00:00:00 -0500 + Understanding Pulsar Wind Nebulae with the SKA + https://arxiv.org/abs/2512.16160 + arXiv:2512.16160v1 Announce Type: new +Abstract: Produced by the interaction between the ``pulsar wind'' powered by the rotational energy of a neutron star and its surroundings, the study of pulsar wind nebulae (PWNe) provides vital insight into the physics of neutron star magnetospheres and ultra-relativistic outflows. Spatially-resolved studies of the continuum and polarized radio emission of these sources are vital for understanding the production of $e^\pm$ in the magnetospheres of neutron stars, the acceleration of these particles to $\gtrsim10^{15}~{\rm eV}$ energies, and the propagation of these particles within the PWN as well as the surrounding interstellar medium. The significant improvements in sensitivity, dynamic range, timing capabilities offered by the Square Kilometer Array have the potential to significantly improve our understanding of the origin of some of the highest energy particles produced in the Milky Way. + oai:arXiv.org:2512.16160v1 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Pierre Auclair-Desrotour, Mohammad Farhat, Gwena\"el Bou\'e, Jacques Laskar + Joseph D. Gelfand, C. -Y. Ng, B. Posselt, Mallory S. E. Roberts, Subir Bhattacharyya, Shi Dai, Rene Breton, Benjamin Stappers, Andrea Possenti, Jason Hessels, Yifan Sun, Moaz Abdelmaguid - FAST-MEPSA: an optimised and faster version of peak detection algorithm MEPSA - https://arxiv.org/abs/2512.10579 - arXiv:2512.10579v1 Announce Type: new -Abstract: We present FAST-MEPSA, an optimised version of the MEPSA algorithm developed to detect peaks in uniformly sampled time series affected by uncorrelated Gaussian noise. Although originally conceived for the analysis of gamma-ray burst (GRB) light curves (LCs), MEPSA can be readily applied to other transient phenomena. The algorithm scans the input data by applying a set of 39 predefined patterns across multiple timescales. While robust and effective, its computational cost becomes significant at large re-binning factors. To address this, FAST-MEPSA introduces a sparser offset-scanning strategy. In parallel, building on MEPSA's flexibility, we introduce a 40th pattern specifically designed to recover a class of elusive peaks that are typically sub-threshold and lie on the rising edge of broader structures - often missed by the original pattern set. Both versions of FAST-MEPSA - with 39 and 40 patterns - were validated on simulated GRB LCs. Compared to MEPSA, the new implementation achieves a speed-up of nearly a factor 400 at high re-binning factors, with only a minor (~4%) reduction in the number of detected peaks. It retains the same detection efficiency while significantly lowering the false positive rate of low significance. The inclusion of the new pattern increases the recovery of previously undetected and sub-threshold peaks. These improvements make FAST-MEPSA an effective tool for large-scale analyses where a robust trade-off between speed, efficiency, and reliability is essential. The adoption of 40 patterns instead of the classical 39 is advisable when an enhanced efficiency in detecting faint events is desired. The code is made publicly available. - oai:arXiv.org:2512.10579v1 - astro-ph.IM + Testing Gravity with Binary Pulsars in the SKA Era + https://arxiv.org/abs/2512.16161 + arXiv:2512.16161v1 Announce Type: new +Abstract: Binary (and trinary) radio pulsars are natural laboratories in space for understanding gravity in the strong field regime, with many unique and precise tests carried out so far, including the most precise tests of the strong equivalence principle and of the radiative properties of gravity. The Square Kilometre Array (SKA) telescope, with its high sensitivity in the Southern Hemisphere, will vastly improve the timing precision of recycled pulsars, allowing for a deeper search of potential deviations from general relativity (GR) in currently known systems. A Galactic census of pulsars will, in addition, will yield the discovery of dozens of relativistic pulsar systems, including potentially pulsar -- black hole binaries, which can be used to test the cosmic censorship hypothesis and the ``no-hair'' theorem. Aspects of gravitation to be explored include tests of strong equivalence principles, gravitational dipole radiation, extra field components of gravitation, gravitomagnetism, and spacetime symmetries. In this chapter, we describe the kinds of gravity tests possible with binary pulsar and outline the features and abilities that SKA must possess to best contribute to this science. + oai:arXiv.org:2512.16161v1 astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.SR + gr-qc + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 10.1016/j.ascom.2025.101040 - Volume 55, April 2026, 101040 - Manuele Maistrello, Romain Maccary, Cristiano Guidorzi + V. Venkatraman Krishnan, L. Shao, V. Balakrishnan, M. Colom i Bernadich, A. Carelo, A. Corongiu, A. Deller, P. C. C. Freire, M. Geyer, E. Hackmann, H. Hu, Z. Hu, J. Kunz, M. Kramer, K. Liu, M. E. Lower, X. Miao, A. Possenti, D. Perrodin, D. S. Pillay, S. Ransom, I. Stairs, B. Stappers, The SKA Pulsar Science Working Group - Is Dark Energy Dynamical in the DESI Era? A Critical Review - https://arxiv.org/abs/2512.10585 - arXiv:2512.10585v1 Announce Type: new -Abstract: We investigate whether the recent DESI DR2 measurements provide or not evidences for dynamical dark energy by exploring the $\omega_0\omega_a$CDM model and its extensions with free $\sum m_{\nu}$ and $N_{\mathrm{eff}}$. Using a comprehensive MCMC analysis with a wide range of cosmological datasets including DESI~DR2 BAO and Ly$\alpha$ data, CMB compressed likelihoods, BBN, cosmic chronometers, and multiple Type~Ia supernova compilations, we assess the statistical preference for departures from $\Lambda$CDM. - oai:arXiv.org:2512.10585v1 - astro-ph.CO + Probing neutron star interiors and the properties of cold ultra-dense matter with the SKAO + https://arxiv.org/abs/2512.16162 + arXiv:2512.16162v1 Announce Type: new +Abstract: Matter inside neutron stars is compressed to densities several times greater than nuclear saturation density, while maintaining low temperatures and large asymmetries between neutrons and protons. Neutron stars, therefore, provide a unique laboratory for testing physics in environments that cannot be recreated on Earth. To uncover the highly uncertain nature of cold, ultra-dense matter, discovering and monitoring pulsars is essential, and the SKA will play a crucial role in this endeavour. In this paper, we will present the current state-of-the-art in dense matter physics and dense matter superfluidity, and discuss recent advances in measuring global neutron star properties (masses, moments of inertia, and maximum rotation frequencies) as well as non-global observables (pulsar glitches and free precession). We will specifically highlight how radio observations of isolated neutron stars and those in binaries -- such as those performed with the SKA in the near future -- inform our understanding of ultra-dense physics and address in detail how SKAO's telescopes unprecedented sensitivity, large-scale survey and sub-arraying capabilities will enable novel dense matter constraints. We will also address the potential impact of dark matter and modified gravity models on these constraints and emphasise the role of synergies between the SKA and other facilities, specifically X-ray telescopes and next-generation gravitational wave observatories. + oai:arXiv.org:2512.16162v1 + astro-ph.HE + astro-ph.IM gr-qc - hep-th - Fri, 12 Dec 2025 00:00:00 -0500 + hep-ph + nucl-th + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Salvatore Capozziello, Himanshu Chaudhary, Tiberiu Harko, Ghulam Mustafa + Avishek Basu, Vanessa Graber, Marcus E. Lower, Marco Antonelli, Danai Antonopoulou, Manjari Bagchi, Prasanta Char, Paulo C. C. Freire, Brynmor Haskell, Huanchen Hu, David I. Jones, Banibrata Mukhopadhyay, Micaela Oertel, Nanda Rea, Violetta Sagun, Benjamin Shaw, Jaikhomba Singha, Benjamin W. Stappers, Tinn Thongmeearkom, Anna L. Watts, Patrick Weltevrede, The SKA Pulsar Science Working Group - Inflation at the End of 2025: Constraints on $r$ and $n_s$ Using the Latest CMB and BAO Data - https://arxiv.org/abs/2512.10613 - arXiv:2512.10613v1 Announce Type: new -Abstract: Inflation elegantly provides initial conditions for the standard model of cosmology, while solving the horizon, flatness, and magnetic monopole problems. Inflationary models make predictions for the tensor-to-scalar ratio $r$ and the spectral index $n_s$ of initial density fluctuations. In light of relevant data releases this year, we present constraints on these two parameters using the latest cosmic microwave background (CMB) and baryon acoustic oscillation data (BAO) available. Using data from Planck, the South Pole Telescope, Atacama Cosmology Telescope, and BICEP/Keck experiments, we derive $n_s=0.9682\,\pm\,0.0032$ and a 95% upper limit of $r<0.034$. This upper limit on $r$ is consistent with the official BICEP/Keck result given the numerical precision of the analyses and our choice to impose the self-consistency relation for single field slow-roll inflation on the tensor power spectrum; the $r$ constraint is not impacted by the additional CMB data. While adding DESI BAO data to the CMB data has a negligible impact on $r$, the $n_s$ constraint shifts upward to $0.9728\,\pm\,0.0029$, which favours monomial inflaton potentials with $N_\star\sim 50$ over Starobinsky $R^2$ or Higgs inflation with $N_\star = 51$ and $N_\star = 55$, respectively. This shift is caused by marginally significant differences between the CMB and DESI data that remain unexplained in the context of the standard model. We show that a class of polynomial $\alpha$-attractor models can predict the CMB and CMB+DESI $n_s$ results with $N_\star=47.1$ and $N_\star=55.1$, respectively. While future data will improve our sensitivity to $r$, robust $n_s$ constraints are just as crucial to differentiate between inflation models. We make the data needed to reproduce the new CMB and BAO results and visualisation tools for $r$-$n_s$ figures to compare to any inflation model available https://github.com/Lbalkenhol/r_ns_2025 . - oai:arXiv.org:2512.10613v1 + The SKAO Pulsar Timing Array + https://arxiv.org/abs/2512.16163 + arXiv:2512.16163v1 Announce Type: new +Abstract: Pulsar timing arrays (PTAs) are ensembles of millisecond pulsars observed for years to decades. The primary goal of PTAs is to study gravitational-wave astronomy at nanohertz frequencies, with secondary goals of undertaking other fundamental tests of physics and astronomy. Recently, compelling evidence has emerged in established PTA experiments for the presence of a gravitational-wave background. To accelerate a confident detection of such a signal and then study gravitational-wave emitting sources, it is necessary to observe a larger number of millisecond pulsars to greater timing precision. The SKAO telescopes, which will be a factor of three to four greater in sensitivity compared to any other southern hemisphere facility, are poised to make such an impact. In this chapter, we motivate an SKAO pulsar timing array (SKAO PTA) experiment. We discuss the classes of gravitational waves present in PTA observations and how an SKAO PTA can detect and study them. We then describe the sources that can produce these signals. We discuss the astrophysical noise sources that must be mitigated to undertake the most sensitive searches. We then describe a realistic PTA experiment implemented with the SKA and place it in context alongside other PTA experiments likely ongoing in the 2030s. We describe the techniques necessary to search for gravitational waves in the SKAO PTA and motivate how very long baseline interferometry can improve the sensitivity of an SKAO PTA. The SKAO PTA will provide a view of the Universe complementary to those of the other large facilities of the 2030s. + oai:arXiv.org:2512.16163v1 + astro-ph.HE astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.IM + gr-qc + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Ryan M. Shannon, N. D. Ramesh Bhat, Aurelien Chalumeau, Siyuan Chen, H. Thankful Cromartie, A. Gopukumar, Kathrin Grunthal, Jeffrey S. Hazboun, Francesco Iraci, Bhal Chandra Joshi, Ryo Kato, Michael J. Keith, Kejia Lee, Kuo Liu, Hannah Middleton, Matthew T. Miles, Chiara M. F. Mingarelli, Aditya Parthasarathy, Daniel J. Reardon, Golam M. Shaifullah, Keitaro Takahashi, Caterina Tiburzi, Riccardo J. Truant, Xiao Xue, Andrew Zic, The SKAO Pulsar Science Working Group + + + Bayesian Smooth-Fit Extrapolation of the $^{12}\mathrm{C}+{}^{12}\mathrm{C}$ Astrophysical $S$ Factor + https://arxiv.org/abs/2512.16169 + arXiv:2512.16169v1 Announce Type: new +Abstract: A Bayesian analysis of the astrophysical $S$ factor for the $^{12}\mathrm{C}+^{12}\mathrm{C}$ fusion reaction is presented, based on available experimental information at carbon--carbon relative energies $E \gtrsim 2~\mathrm{MeV}$, including direct measurements, indirect Coulomb-renormalized Trojan Horse Method (THM) results, and recent inverse-kinematics data. The Bayesian inference is performed on the quantity $\log_{10}S^{*}(E)$ rather than on $S^{*}(E)$ itself, which naturally accommodates the wide dynamic range of the data and leads to approximately Gaussian uncertainties. The logarithm of the astrophysical factor is parametrized by a quadratic polynomial in energy, and the posterior distribution of the fit coefficients is determined using a weighted Bayesian regression. From this posterior, a global median $S^{*}(E)$ curve is constructed, and the associated covariance matrix is used to define a low/medium/high (LO/MED/HI) band corresponding to a $68\%$ credible interval. + Particular emphasis is placed on the extrapolation below $E_{\mathrm{cm}}=2~\mathrm{MeV}$, where the fusion reaction rate is most relevant for stellar carbon burning. At $E_{\mathrm{cm}}=1.5~\mathrm{MeV}$, the posterior distribution yields $S_{\mathrm{global}}^{*}(1.5~\mathrm{MeV})= \left(2.13^{+0.01}_{-0.01}\right)\times10^{16}\,\mathrm{keV\,b}, $ corresponding to a $68\%$ credible interval. The extracted result is consistent with recent inverse-kinematics measurements and with Coulomb-corrected Trojan Horse Method constraints, providing a tightly constrained estimate of the $^{12}\mathrm{C}+^{12}\mathrm{C}$ fusion $S$ factor in the energy region relevant for stellar carbon burning. + oai:arXiv.org:2512.16169v1 + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + A. M. Mukhamedzhanov + + + Physics-Informed Neural Networks for Modeling the Martian Induced Magnetosphere + https://arxiv.org/abs/2512.16175 + arXiv:2512.16175v1 Announce Type: new +Abstract: Understanding the magnetic field environment around Mars and its response to upstream solar wind conditions provide key insights into the processes driving atmospheric ion escape. To date, global models of Martian induced magnetosphere have been exclusively physics-based, relying on computationally intensive simulations. For the first time, we develop a data-driven model of the Martian induced magnetospheric magnetic field using Physics-Informed Neural Network (PINN) combined with MAVEN observations and physical laws. Trained under varying solar wind conditions, including B_IMF, P_SW, and {\theta}_cone, the data-driven model accurately reconstructs the three-dimensional magnetic field configuration and its variability in response to upstream solar wind drivers. Based on the PINN results, we identify key dependencies of magnetic field configuration on solar wind parameters, including the hemispheric asymmetries of the draped field line strength in the Mars-Solar-Electric coordinates. These findings demonstrate the capability of PINNs to reconstruct complex magnetic field structures in the Martian induced magnetosphere, thereby offering a promising tool for advancing studies of solar wind-Mars interactions. + oai:arXiv.org:2512.16175v1 + astro-ph.EP + cs.LG + physics.space-ph + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - L. Balkenhol, E. Camphuis, F. Finelli, K. Benabed, F. R. Bouchet, J. Carron, S. Galli, E. Hivon, A. R. Khalife, L. Knox, C. L. Reichardt, A. Vitrier, W. L. K. Wu + Jiawei Gao, Chuanfei Dong, Chi Zhang, Yilan Qin, Simin Shekarpaz, Xinmin Li, Liang Wang, Hongyang Zhou, Abigail Tadlock - nDspec: a new Python library for modelling multi-dimensional datasets in X-ray astronomy - https://arxiv.org/abs/2512.10615 - arXiv:2512.10615v1 Announce Type: new -Abstract: The current fleet of X-ray telescopes produces a wealth of multi-dimensional data, allowing us to study sources in time, photon energy and polarization. At the same time, it has become increasingly clear that progress in our physical understanding will only come from studying these sources in multiple dimensions simultaneously. Enabling multi-dimensional studies of X-ray sources requires new theoretical models predicting these data sets, new methods to analyse them and a software framework to combine data, models and methods efficiently. In this paper, we introduce the alpha release of nDspec, a new python-based library designed to allow users to model one- and multi-dimensional datasets common to X-ray astronomy. In the alpha release, we focus on modelling time-averaged data as well as Fourier spectral-timing mode, but highlight how additional dimensions can be added. We discuss design philosophy and current features, and showcase an example use case by characterizing a NICER observation of a black hole X-ray binary. We also highlight current plans for extensions to other dimensions and new features. - oai:arXiv.org:2512.10615v1 + Fastest or Significant: A Systematic Framework for Validating Global Minimum Variability Timescale Measurements of Gamma-ray Bursts + https://arxiv.org/abs/2512.16204 + arXiv:2512.16204v1 Announce Type: new +Abstract: The minimum variability timescale (MVT) is a key observable used to probe the central engines of Gamma-Ray Bursts (GRBs) by constraining the emission region size and the outflow Lorentz factor. However, its interpretation is often ambiguous: statistical noise and analysis choices can bias measurements, making it difficult to distinguish genuine source variability from artifacts. Here we perform a comprehensive suite of simulations to establish a quantitative framework for validating Haar-based MVT measurements. We show that in multi--component light curves, the MVT returns the most statistically significant structure in the interval, which is not necessarily the fastest intrinsic timescale, and can therefore converge to intermediate values. Reliability is found to depend jointly on the MVT value and its signal-to-noise ratio ($\mathrm{SNR}_{\mathrm{MVT}}$), with shorter intrinsic timescales requiring proportionally higher $\mathrm{SNR}_{\mathrm{MVT}}$ to be resolved. + We use this relation to define an empirical MVT Validation Curve, and provide a practical workflow to classify measurements as robust detections or upper limits. Applying this procedure to a sample of Fermi-GBM bursts shows that several published MVT values are better interpreted as upper limits. These results provide a path toward standardizing MVT analyses and highlight the caution required when inferring physical constraints from a single MVT measurement in complex events. + oai:arXiv.org:2512.16204v1 astro-ph.HE astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Matteo Lucchini, Benjamin Ricketts, Phil Uttley, Daniela Huppenkothen + S. Bala, P. Veres, A. Goldstein, R. Sonawane, R. Samanta, S. Iyyani - Stellar masses and mass ratios for Gaia open cluster members - https://arxiv.org/abs/2512.10616 - arXiv:2512.10616v1 Announce Type: new -Abstract: Context: Unresolved binaries in star clusters can bias stellar and cluster mass estimates, making their proper treatment essential for studying cluster dynamics and evolution. Aims: We aim to develop a fast and robust framework for jointly deriving stellar masses and multiplicity statistics of member stars, together with optimal cluster parameters. Methods: We use Gaia DR3 parallaxes together with multi-band photometry of open cluster (OC) members to infer stellar masses and binary mass-ratios through simulation-based inference (SBI), while iteratively fitting the cluster parameters. The validation of our SBI framework on simulated clusters demonstrates that the inclusion of infrared photometry significantly improves the detection of low mass-ratio binaries. The minimum mass-ratio threshold for reliably identifying unresolved binaries depends on cluster properties and the available photometry, but typically lies below $q=0.5$. Results: Applying our method to 42 well-populated OCs, we derive a catalogue of stellar masses and mass-ratios for 27201 stars, achieving typical uncertainties of 0.08 in $q$ and $0.01\,\mathrm{M}_\odot$ in the primary stellar mass. We analyse the archetype OCs M67 and NGC 2360 in detail, including mass segregation and mass-ratio distribution among other characteristics, while deriving multiplicity fractions for the rest of the sample. We find evidence that the high mass-ratio ($q\geq 0.6$) binary fraction shows a strong correlation with the age and a weak anti-correlation with the cluster metallicity. Furthermore, the variation of the binary fraction with stellar mass in OCs shows strong accordance with the observed dependence for field stars heavier than $\gtrsim0.6\,\mathrm{M}_\odot$. Conclusions: Our work paves a path for future population-level investigations of multiplicity statistics and precision stellar masses in extended samples of OCs. - oai:arXiv.org:2512.10616v1 + Unveiling the properties and origin of massive quenched galaxies at $z\ge2$ in the COLIBRE hydrodynamical simulations + https://arxiv.org/abs/2512.16208 + arXiv:2512.16208v1 Announce Type: new +Abstract: JWST has uncovered a substantial population of Massive ($M_{\star} \gtrsim 10^{10 }\mathrm{M_{\odot}}$), Quenched Galaxies (MQGs) in the early Universe ($z \gtrsim 2$), whose properties challenge current galaxy formation models. In this paper, we examine this population of MQGs within the new COLIBRE cosmological hydrodynamical simulations. We report number densities and stellar mass functions in broad agreement with the latest observations. The predicted quenching and formation timescales are qualitatively consistent with observational inferences. Leveraging the state-of-the-art physics in COLIBRE, the model predicts that MQGs have dust and $\rm H_{2}$ fractions more than $1$ dex lower than their massive star-forming counterparts; while their sizes and kinematics remain broadly similar. We further explore the processes driving galaxies to become massive and quenched in COLIBRE, identifying active galactic nucleus (AGN) feedback as the primary quenching mechanism. Compared to star-forming galaxies of similar mass, MQGs host more massive black holes (BHs) and exhibit higher star formation efficiencies. These differences arise from their environments, particularly at local ($\rm 0.3\,cMpc$) to intermediate scales ($\rm 1.0\,cMpc$) before quenching, where overdense regions are associated with enhanced gas inflows, higher BH accretion and, hence, feedback power. We find that about $55\%$ of MQGs survive as the main progenitors of $z=0$ galaxies when they are selected at $z=3$, although up to $55\%$ experience rejuvenation episodes. Our results provide robust predictions for MQGs, show that tensions with observations are reduced when an effective observational uncertainty is forward-modelled, and clarify the mechanisms behind their origin. + oai:arXiv.org:2512.16208v1 astro-ph.GA - astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.CO + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Sagar Malhotra, Alfred Castro-Ginard, Friedrich Anders, Carme Jordi, Judit Donada, Xavier Luri, Lola Balaguer-N\'u\~nez, Songmei Qin, Yueyue Jiang, Andrija \v{Z}upi\'c + \'Angel Chandro-G\'omez (International Centre for Radio Astronomy Research, ARC Centre for All-Sky Astrophysics in 3 Dimensions), Claudia del P. Lagos, Chris Power, Willian M. Baker, Alejandro Ben\'itez-Llambay, Evgenii Chaikin, Harry G. Chittenden, Camila Correa, Carlos S. Frenk, Filip Hu\v{s}ko, Robert J. McGibbon, Themiya Nanayakkara, Sylvia Ploeckinger, Alexander J. Richings, Matthieu Schaller, Joop Schaye, James W. Trayford - OutLines: Modeling Spectral Lines from Winds, Bubbles, and Outflows - https://arxiv.org/abs/2512.10650 - arXiv:2512.10650v1 Announce Type: new -Abstract: Common methods for studying the kinematics and geometry of outflowing gas rely on modeling emission and absorption lines in integrated spectra using methods that are not physically motivated, including empirical quantiles or fitting multiple Gaussian or Voigt profiles. Such methods are not always consistent with the interpretation of these features and, as a result, miss key underlying physics and can even lead to inaccurate interpretations of observations. To address this problem, we present the publicly available python code OutLines, which provides astrophysical models of spectral emission and absorption line profiles produced by outflows in a variety of environments. The OutLines code accounts for differences in parameterization of the velocity field and density profile while allowing for different outflow geometries, making OutLines versatile and useful for a wide variety of astrophysical phenomena. We demonstrate the wide applicability of OutLines by using the code to model line profiles in an H II region knot, super star clusters, a starburst galaxy, and an AGN. In each of these contexts, we illustrate how OutLines can illuminate key underlying physics in ways that improve our scientific understanding and address important open questions in astronomy, including the key mechanisms in the baryon cycle, the evolution of H II regions and galaxies, and even Lyman continuum escape. OutLines will be a critical resource as massively multiplexed spectroscopic surveys like WEAVE-LOFAR and 4MOST/WAVES come online, providing the means to probe feedback kinematics with deeper, higher resolution spectroscopy for unprecedented large samples of galaxies. - oai:arXiv.org:2512.10650v1 + Infrared SED Modeling of Velocity-Excess Maser Sources: Identifying Incipient Water-Fountain Candidates + https://arxiv.org/abs/2512.16209 + arXiv:2512.16209v1 Announce Type: new +Abstract: We investigated whether "velocity excess" in circumstellar maser lines can diagnose the earliest evolutionary phases of Water Fountains (WFs). Here we define "velocity excess" as maser emission (e.g., H$_2$O 22.235 GHz or OH 1665/1667 MHz) detected at velocities outside the velocity range of the OH 1612 MHz line, which traces the terminal expansion velocity of a spherical circumstellar envelope (CSE). Such excess velocities serve as an indicator of gas motions deviating from spherical expansion and may signify the onset of asymmetric outflows. Based on recent studies (Fan et al.2024; Xie et al.2025), we analyzed 17 sources showing velocity excess and fitted their infrared spectral energy distributions (SEDs) with the one-dimensional radiative transfer code DUSTY. Seven sources are well reproduced, implying outer CSEs that remain nearly spherical despite inner asymmetries. Among these, five exhibit single-peaked, AGB-like SEDs and two show double-peaked, post-AGB-like profiles. IRAS variability indices and NEOWISE-R light curves reveal pulsations (~600-1000 days) in three sources, supporting their AGB classification. Considering the magnitude of the velocity excess, two objects-IRAS 19229+1708 and IRAS 19052+0922-may represent the earliest or incipient WF phase, in which asymmetric outflows are beginning to emerge within otherwise spherical envelopes. These results support a morphological sequence in which bipolar jets and tori arise first in the central regions while the outer CSE remains spherical, and they show that selecting WF candidates via velocity excess effectively identifies objects at the onset of jet formation and early morphological transformation. + oai:arXiv.org:2512.16209v1 + astro-ph.SR astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by-nc-nd/4.0/ - Sophia R. Flury + Jia-Yong Xie, Jun-ichi Nakashima, Yong Zhang - Can accreting isolated neutron stars be detected? - https://arxiv.org/abs/2512.10666 - arXiv:2512.10666v1 Announce Type: new -Abstract: We perform population synthesis modeling of isolated neutron stars in the Milky Way over its lifetime. Compared with previous studies, we use more detailed models of the interstellar medium and the magneto-rotational evolution of neutron stars. We demonstrate that presently, the spin-down rate at the propeller stage is the main uncertain factor that influences the number of accreting isolated neutron stars. If the propeller stage duration allows neutron stars to begin accreting matter from the interstellar medium and if the efficiency of accretion is high, then the number of accreting isolated neutron stars in eROSITA data can reach ~a few thousand. Still, uncertainties in spin-down at the propeller stage and in the accretion process can drastically decrease this number. We suggest that future observations of neutron stars in wide low-mass binaries recently discovered by Gaia can clarify these issues. - oai:arXiv.org:2512.10666v1 - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + ALMA and JWST Identification of Faint Dusty Star-Forming Galaxies up to z~8 + https://arxiv.org/abs/2512.16215 + arXiv:2512.16215v1 Announce Type: new +Abstract: We exploit a new sample of around 400 bright dusty galaxies from the ALMA CHAMPS Large Program, together with the rich JWST multi-band data products in the COSMOS field, to explore and validate new selection methods for identifying dusty star-forming galaxies (DSFGs). Here, we present an effective empirical selection criterion based on a newly defined parameter: I_star = log(M_star) x log(SFR). Incorporating the F277W-F444W color as a second parameter further improves the purity of the selection. We then apply this method to the COSMOS2025 catalog to search for fainter dusty galaxy candidates below the ALMA CHAMPS detection limit and, through a stacking technique, identify a population of high-redshift (z=6-8) DSFGs with an average flux density of$S_1.2mm = 0.15uJy and a space density of ~6E-6 Mpc^-3. This faint population seems to have been missed by most of the previous submillimeter/millimeter surveys, and ground- and space-based UV-to-NIR surveys. Finally, we discuss the possibility of an evolutionary connection between the z > 10 UV-bright galaxies recently discovered by JWST, the faint dusty z=6-8 galaxies identified here, and the population of z=3-5 massive quiescent galaxies, potentially linked as progenitor-descendant populations based on their abundance, redshifts, and stellar masses. + oai:arXiv.org:2512.16215v1 + astro-ph.GA + astro-ph.IM + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Jorge A. Zavala, Andreas L. Faisst, Manuel Aravena, Caitlin M. Casey, Jeyhan S. Kartaltepe, Felix Martinez III, John D. Silverman, Sune Toft, Ezequiel Treister, Hollis B. Akins, Hiddo Algera, Karina Barboza, Andrew J. Battisti, Gabriel Brammer, Jackie Champagne, Nicole E. Drakos, Eiichi Egami, Xiaohui Fan, Maximilien Franco, Yoshinobu Fudamoto, Seiji Fujimoto, Steven Gillman, Ghassem Gozaliasl, Santosh Harish, Xiangyu Jin, Koki Kakiichi, Darshan Kakkad, Anton M. Koekemoer, Ruqiu Lin, Daizhong Liu, Arianna S. Long, Georgios E. Magdis, Sinclaire Manning, Crystal L. Martin, Jed McKinney, Romain Meyer, Giulia Rodighiero, Victoria Salazar, David B. Sanders, Marko Shuntov, Margherita Talia, Takumi S. Tanaka, Feige Wang, Wuji Wang, Stephen M. Wilkins, Jinyi Yang, Min S. Yun + + + Weakened Inspirals I: High Mass Ratio Common Envelope Interactions in RGB Stars + https://arxiv.org/abs/2512.16225 + arXiv:2512.16225v1 Announce Type: new +Abstract: The common envelope (CE) interaction between an expanding giant star and a compact companion typically leads to a rapid orbital decay, ending in either a merger or the formation of a close binary. However, the existence of post-red giant and post-asymptotic giant branch binaries with separations of 100 to 800 Rsun challenges this standard picture, as these systems appear to have experienced strong interactions without undergoing a classic CE inspiral. In this work, we investigate the effect of high mass ratio, q = M2/M1, on the CE inspiral using three-dimensional hydrodynamical simulations performed with the smoothed particle hydrodynamics code PHANTOM. The primary is a 0.88 Msun, 90 Rsun red giant branch star, while the companion masses span q = 0.68 to 1.5. Higher mass ratios lead to wider post-CE separations, with a maximum of approximately 40 Rsun. The pre-CE mass transfer phase is longer for larger companion masses, and for q greater than or equal to 1 the inspiral becomes significantly more stable, broadly consistent with analytical expectations. This phase is not fully converged with respect to numerical resolution, and higher resolution simulations are expected to further increase its duration and stability. Although higher q systems show enhanced mass loss through the L2 and L3 Lagrange points, we find that circumbinary discs are more likely to form from fallback of bound envelope material. Fallback times are short, of order a few hundred years, and fallback radii lie well outside the binary, between 0.5 and 5 au, where discs are expected to spread efficiently through viscous torques. While high mass ratio systems produce wider post-interaction separations, these remain smaller than those observed. In contrast, fallback-formed discs have properties consistent with observed circumbinary discs. + oai:arXiv.org:2512.16225v1 + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Marina Afonina, Anton Biryukov, Sergei Popov + Jack Nibbs, Orsola De Marco, Lionel Siess, Ryosuke Hirai, Daniel Price - Constraints on the Population of Common Sources of Gravitational Waves and High-Energy Neutrinos with IceCube During the Third Observing Run of the LIGO and Virgo Detectors - https://arxiv.org/abs/2512.10707 - arXiv:2512.10707v1 Announce Type: new -Abstract: The discovery of joint sources of high-energy neutrinos and gravitational waves has been a primary target for the LIGO, Virgo, KAGRA, and IceCube observatories. The joint detection of high-energy neutrinos and gravitational waves would provide insight into cosmic processes, such as progenitor dynamics and outflows. The joint detection of multiple cosmic messengers can also elevate the significance of the observation when some or all of the constituent messengers are sub-threshold, not significant enough to declare their detection individually. Leveraging data from the LIGO, Virgo, and IceCube observatories, we conducted an archival investigation of sub-threshold multimessenger events. Complementing previous analyses, we used minimal assumptions to search for common sources of sub-threshold gravitational-wave and high-energy neutrino candidates during the third observing run (O3) of the Advanced LIGO and Advanced Virgo detectors. Our search did not identify significant joint sources. We therefore derive constraints on the rate density of joint sources for each compact binary merger population as a function of the energy emitted in neutrinos. Only a fraction of the gravitational-wave sources emit neutrinos, if the neutrino emission has high bolometric energy ($>10^{52}$ to $10^{54}$ erg). - oai:arXiv.org:2512.10707v1 + Expanding Horizons - Transforming Astronomy in the 2040s Time-Domain Multi-Messenger Astronomy in the 2040s: EM Follow-up of LGWA Sources + https://arxiv.org/abs/2512.16264 + arXiv:2512.16264v1 Announce Type: new +Abstract: The coming decades will see gravitational-wave (GW) astronomy expand decisively into the mHz-Hz frequency range, opening access to a population of compact binaries that are currently invisible or only detectable moments before merger. The Lunar Gravitational Wave Antenna (LGWA) concept is designed to probe this gap, enabling continuous observation of compact binaries over months to years prior to coalescence, and detecting sources inaccessible to both space-based mHz detectors and current ground-based >10 Hz facilities. This new GW window fundamentally alters the landscape of time-domain multi-messenger astronomy. Rather than reacting to mergers after the fact, LGWA enables predictive, scheduled electromagnetic (EM) follow-up, transforming how compact-object mergers, their environments, and their astrophysical channels are studied. However, fully exploiting LGWA discoveries requires EM capabilities that do not exist today and are unlikely to be available by the 2030s, particularly for wide-area, rapid, spectroscopically rich follow-up at optical and near-infrared wavelengths. This White Paper identifies the key science cases enabled by LGWA that motivate new ground-based capabilities in the 2040s. + oai:arXiv.org:2512.16264v1 + astro-ph.IM astro-ph.HE + astro-ph.SR gr-qc - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.22323/1.501.0972 - Do\u{g}a Veske (for the IceCube Collaboration, the LIGO Scientific Collaboration, the Virgo Collaboration,,the KAGRA Collaboration), Zsuzsa M\'arka (for the IceCube Collaboration, the LIGO Scientific Collaboration, the Virgo Collaboration,,the KAGRA Collaboration), Albert Zhang (for the IceCube Collaboration, the LIGO Scientific Collaboration, the Virgo Collaboration,,the KAGRA Collaboration) + http://creativecommons.org/licenses/by-sa/4.0/ + F. Patat, S. Piranomonte, S. Benetti, A. Bonforte, R. Della Ceca, G. Di Rico, A. Frigeri, J. Harms, M. Olivieri, A. Perali, P. Severgnini, A. Stallone, the LGWA Collaboration - Model independent approach towards measuring expansion and growth factor from next generation galaxy clustering and lensing angular power spectrum - https://arxiv.org/abs/2512.10742 - arXiv:2512.10742v1 Announce Type: new -Abstract: In this work we perform Fisher forecasts on the expansion and the growth factors following model independent approaches from 3x2pt joint analysis of the galaxy lensing, clustering, and their cross-correlated spectra at the linear, and extending as well to non linear scales. For that, instead of choosing a specific model for the matter power spectrum, the main ingredient of these probes, we express it by parametrizing its components, such as the expansion and the growth factor, and those of the standard halo model and excursion set theory in several z bins, besides to the different bias and non-linear bias modelling functions. We apply the technique to Euclid, Rubin and SKA public specifications in the range 0.2 < z < 1.8 and show that one can then obtain model-independent constraints of the expansion E(z i ) and the growth factor G(z i ). We also show the change in gain in precision at each z- shell when going from pessimistic cut at linear scales to more optimistic non-linear settings, or the difference between using each survey alone or a combination of all of them, or the impact from fixing or adding more degrees of freedom in the non-linear modeling. We found that, in the most agnostic case, one can still reach high precision on E(z i ) in the order of the percent level when combining the three surveys at once while the growth factor G(z i ) has for the same settings one order of magnitude weaker constraints. We also found for both factors, an improvement that can reach one order of magnitude in precision when passing from linear to non-linear scales. We conclude that we will be able to constrain the two important factors of the background evolution and structure formation of the Universe when using non linear scales and the combined power of future surveys even in the most agnostic approaches. - oai:arXiv.org:2512.10742v1 - astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + Radio frequency interference identification using eigenvalue decomposition for multi-beam observations + https://arxiv.org/abs/2512.16278 + arXiv:2512.16278v1 Announce Type: new +Abstract: With the installation of next-generation phased array feed (PAF) receivers on radio telescopes, there is an urgent need to develop effective and computationally efficient radio frequency interference (RFI) mitigation methods for large-scale surveys. Here we present a new RFI mitigation package, called mRAID (multi-beam RAdio frequency Interference Detector), which uses the eigenvalue decomposition algorithm to identify RFI in cross-correlation matrix (CCM) of data recorded by multiple beams. When applied to high time-resolution pulsar search data from the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), mRAID demonstrates excellent performance in identifying RFI over short timescales, thereby enhancing the efficiency of pulsar and fast radio burst (FRB) searches. Since the computation of the CCM and the eigenvalue decomposition for each time sub-integration and frequency channel are independent, the process is fully parallelisable. As a result, mRAID offers a significant computational advantage over commonly used RFI detection methods. + oai:arXiv.org:2512.16278v1 + astro-ph.IM + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Ziad Sakr + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Juntao Bai, Shi Dai, Na Wang, Stefan Os{\l}owski, Shuangqiang Wang, George Hobbs, Jianping Yuan, Wenming Yan, Qijun Zhi, Lunhua Shang, Xin Xu, Shijun Dang, De Zhao - A "New Hope" for Moon Formation: Presenting a Multiple Impact Pathway - https://arxiv.org/abs/2512.10757 - arXiv:2512.10757v1 Announce Type: new -Abstract: The leading hypothesis for the origin of the Moon, that of a single giant impact, faces significant challenges. These include either the need for an impactor with a near-identical composition to Earth or an extremely high-mass or high-energy impact to achieve near-complete material mixing. In this paper we explore an alternative, the "multiple impact hypothesis", which relaxes the compositional constraints on both the target and projectile, and allows for the consideration of more probable, less extreme impacts that steadily grow the Earth and Moon to their current size over several impact events. Using the hydrodynamical code SWIFT, we simulate "chains" of impacts and follow the growth of a moon around a planet analogous to our own. Our results demonstrate that chains of three or more impacts can produce systems comparable to the Earth-Moon system whilst achieving higher compositional similarities than the canonical giant impact scenario. This presents the multiple impact hypothesis as a promising alternative to the single large impact scenario for the origin of the Moon. - oai:arXiv.org:2512.10757v1 - astro-ph.EP - Fri, 12 Dec 2025 00:00:00 -0500 + Astrophysical Implications of Eccentricity in Gravitational Waves from Neutron Star-Black Hole Binaries + https://arxiv.org/abs/2512.16289 + arXiv:2512.16289v1 Announce Type: new +Abstract: The gravitational-wave signal from the neutron star-black hole (NSBH) merger GW200105 is consistent with this binary having significant orbital eccentricity close to merger. This raises the question of how an eccentric NSBH might form. Compact object binaries that form via isolated binary star evolution should radiate away any orbital eccentricity long before their gravitational-wave signal enters the sensitive frequency range of the LIGO-Virgo-KAGRA detector network. Meanwhile, dynamical environments -- which can be conducive to mergers on eccentric orbits -- produce very few NSBHs. We estimate the minimum measurable eccentricity of NSBHs at 10 Hz orbit-averaged gravitational-wave frequency, $e_{\mathrm{min},10}$, finding that for GW200105, GW200115, and GW230529-like systems, $e_{\mathrm{min},10}$ is O(0.01). For a GW190814-like unequal-mass binary with significant higher-order mode content, $e_{\mathrm{min},10}=0.003$; this is an order of magnitude lower than when higher-order modes are not present. For dominant-mode signals from eccentric binaries with $m_2=1.5$ M$_\odot$ and a range of total masses from $3\,{\rm M_\odot} \leq M \leq50\,\rm M_\odot$, we find $0.008\leq e_{\mathrm{min},10}\leq0.022$. The relationship between $M$ and $e_{\mathrm{min},10}$ is linear when the binaries are non-spinning. When the binaries are maximally spin-precessing, $e_{\mathrm{min},10}$ decreases as mass ratio becomes more unequal. We estimate the sensitivity of a quasi-circular templated search to a population of NSBHs from field triples, finding that we recover only 27% of our simulated population. Finally, we show that if ~1/3 of present NSBH detections are measurably eccentric, then all of them are consistent with an isolated field triple origin. + oai:arXiv.org:2512.16289v1 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - 10.1093/mnras/staf2084 - Harrison Davies, Philip J. Carter, Louis Eddershaw, Jingyao Dou, Zo\"e M. Leinhardt + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Isobel Romero-Shaw, Jakob Stegmann, Gonzalo Morras, Andris Dorozsmai, Michael Zevin - Applying the BF method on the DESI evidence for dynamical dark energy models - https://arxiv.org/abs/2512.10763 - arXiv:2512.10763v1 Announce Type: new -Abstract: Recent baryon acoustic oscillation measurements from the DESI, when combined with CMB data and Type Ia supernovae observations, indicate a preference for dynamical dark energy when considering the Chevallier-Polarski-Linder (CPL) model, over the standard {\Lambda}CDM or the wCDM model. However, the Bayes factor, a key metric for model comparison, remains inconclusive on which model is preferred. This paper applies the BF method, that integrates both Bayesian and frequentist approaches to DESI data to address the limitations of purely frequentist or Bayesian methods. It consists in considering the Bayes factor as a random variable and calculates its distribution, that results from values computed in a frequentist approach after perturbing the data following the model considered. We apply this hybrid method to DESI data, comparing the CPL and w models under various prior conditions, including weak and strong priors, and theory-informed priors. We find that, when the traditional bayes factor is considered, that weak priors favor the w model over CPL, while strong priors favor CPL. Additionally, theory-informed priors further enhance the preference for the w model. While when we apply the BF method, the preference for CPL over w is seen in all cases albeit with similar but reduced impact on the p-value from the different prior considerations. We also tried to generalize further, by perturbing as well the covariance matrix following the model considered, and found that, in general, the current data in that case is not stringent enough to disentangle between the two models. Our results demonstrate that varying the Bayes factor as a random variable, providing that the covariance matrix is kept as model independent, provides a robust model comparison, reducing the impact of prior dependence as well as offering quantitative assessment of the preferences of the competing models.(abridged) - oai:arXiv.org:2512.10763v1 - astro-ph.CO - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + The dominant role of dark matter halo in quenching central galaxies + https://arxiv.org/abs/2512.16290 + arXiv:2512.16290v1 Announce Type: new +Abstract: Understanding the quenching of star formation in central galaxies remains a core challenge in galaxy evolution. Two decades ago, the concept of halo quenching was introduced as a dominant mechanism, positing that massive central galaxy quenching is governed by the thermodynamics of gas predominantly influenced by dark matter halos. However, a vastly increasing body of observational evidence consistently indicates that quenching correlates predominantly with central properties like velocity dispersion, bulge mass, and black hole mass. When these properties are controlled, halo mass appears to show weak influence, supporting AGN feedback as the primary mechanism. A recurring key issue, however, is that these studies rely on halo masses derived via abundance matching (AM). Direct observational measurements from weak lensing, satellite kinematics, and galactic dynamics reveal that AM systematically overestimates halo masses of star-forming centrals while underestimating those of passive ones. To accurately assess the true role of halo mass. we re-estimated halo masses for SDSS groups; the resulting halo mass function and stellar-to-halo mass relations (SHMRs) for both populations match theoretical predictions and weak lensing measurements. Using these improved masses, we find direct observational evidence that halo mass is the dominant factor in quenching central galaxies, with a clear threshold at $M_{h}\sim 10^{12.1}M_\odot; $. By applying a simple correction to AM data using weak lensing-derived SHMRs, we demonstrate that previous claims regarding the dominance of central properties stem primarily from systematic biases in AM halo masses. Our results suggest that the significance of AGN feedback is primarily manifested in halos above this mass threshold, in galaxies already primed for quenching. In other words, AGN feedback appears to become effective in halos above this mass threshold. + oai:arXiv.org:2512.16290v1 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Ziad Sakr + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Dingyi Zhao, Yingjie Peng - Hidden No More: Spotlight on tidal disruption events in active galactic nuclei - https://arxiv.org/abs/2512.10764 - arXiv:2512.10764v1 Announce Type: new -Abstract: Tidal disruption events (TDEs) are typically discovered in previously quiescent galaxies. However, earlier studies have revealed a handful of TDEs occurring in pre-existing active galactic nuclei (AGNs). We discuss AT2019aalc, a promising TDE candidate in an AGN, and compare it to similar sources. We also explore Bowen fluorescence flares, a newly identified class of flaring supermassive black holes, as potential members of the TDE in AGN transient class. We aim to connect the observed properties of these flares with the expectations of TDE-in-AGN simulations. - oai:arXiv.org:2512.10764v1 - astro-ph.GA - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Multi-Energy Proton Events and Geomagnetic Storms in Solar Cycles 23 and 24 + https://arxiv.org/abs/2512.16296 + arXiv:2512.16296v1 Announce Type: new +Abstract: Solar energetic protons (SEPs) in different energy channels from 10 to above 100 MeV are analyzed and their relationship to solar and geomagnetic activity is investigated. We performed temporal association analysis between the SEPs, solar flares (SFs), coronal mass ejections (CMEs) and geomagnetic storms (GSs) that occurred during solar cycles 23 and 24. The energy dependencies between the SEPs and the strength of the space weather activity are evaluated and presented. + oai:arXiv.org:2512.16296v1 + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-sa/4.0/ - Patrik Mil\'an Veres + http://creativecommons.org/licenses/by/4.0/ + SES proceedings 2020 + Rositsa Miteva, Susan W. Samwel, Svetoslav Zabunov - Chemical enrichment in LINERs from MaNGA. II. Characterizing the shape of their radial metallicity gradients - https://arxiv.org/abs/2512.10769 - arXiv:2512.10769v1 Announce Type: new -Abstract: Chemical abundance radial gradients provide key information on how the processes that affect chemical enrichment of the gas-phase interstellar medium (ISM) act at different galaxy scales. Whereas in the last decades there has been an increase in the number of galaxies studied with integral field spectroscopy, there is still not a clear picture on a subsequent characterization of the chemical abundance radial gradients in galaxies hosting Active Galactic Nuclei (AGNs). This lack of analysis is even more accentuated in the case of low-ionization nuclear emission-line regions (LINERs). For the first time, we analyze the chemical abundance radial gradients in a sample of LINER-like galaxies, whose nuclear emission has been previously (Paper I) discussed. We use a sample of 97 galaxies from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), whose nuclear regions show LINER-like emission. We use the open-source code HII-CHI-Mistry to estimate the chemical abundance ratios 12+log(O/H) and log(N/O) in the HII regions across the disks in our sample, as well as in the nuclear parts where the LINER-like activity dominates. To fit the radial profiles we use a piecewise methodology which uses a non-fixed number of breaks to find the best fit for the data. We obtain that majority of our sample of galaxies exhibits departures from the single linear gradient both in 12+log(O/H) and log(N/O) (as expected from the inside-out scenario). We investigate whether these departures are driven by galaxy properties (stellar mass, neutral gas mass, stellar velocity dispersion), finding not correlation at all. We also report that in most cases there is no correlation between the shape of the 12+log(O/H) and log(N/O) radial profiles. We propose a model in which AGN (feed)back, acting at different scales depending on the galaxy and its evolutionary stage, might be responsible for these departures. - oai:arXiv.org:2512.10769v1 - astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Discovery of a rapidly evolving global magnetic field in the M-dwarf YZ Cet and constraints on the magnetic field of its planet YZ Cet b + https://arxiv.org/abs/2512.16298 + arXiv:2512.16298v1 Announce Type: new +Abstract: We present a spectropolarimetric study of the nearby M4.5V exoplanet host star YZ Cet, based on near-infrared observations obtained with the SpectroPolarim\`etre InfraRouge (SPIRou) at the Canada--France--Hawaii Telescope. We detect striking changes in the large-scale magnetic field strength and geometry over the course of just a few stellar rotations, a level of short-term global magnetic field evolution rarely reported in M dwarfs. We modeled the temporal variation of the longitudinal magnetic field using a Gaussian regression process, which allowed us to robustly determine the stellar rotation period and quantify the evolution timescale of the magnetic field. Independent Zeeman Doppler Imaging reconstructions of the two epochs confirm a significant reconfiguration of the star's global magnetic strength and topology. The detection of a weaker, complex, axisymmetric magnetic field (mean $|B| \sim 201$~G), which changes into a stronger, non-axisymmetric, dipole-dominated field (mean $|B| \sim 276$~G) over a few rotation cycles, is in contrast to results from similar fully convective M-dwarf stars. YZ Cet is known to exhibit polarized radio bursts potentially driven by auroral radio emission from star--planet interaction (SPI). By combining our magnetic maps with recent radio observations, we refine the constraints on the magnetic field strength of the innermost planet, YZ Cet b. These results underscore the importance of monitoring stellar magnetic variability to interpret multi-wavelength SPI signatures and to characterize the magnetospheres of potentially habitable exoplanets. + oai:arXiv.org:2512.16298v1 + astro-ph.SR + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Borja P\'erez-D\'iaz, Jos\'e M. V\'ilchez, Enrique P\'erez Montero, Igor A. Zinchenko, Brian Tapia-Contreras, Patricia B. Tissera + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Ayan Biswas, Colin P. Folsom, James A. Barron, Gregg A. Wade, Stefano Bellotti, Corrado Trigilio - Pressure and Star Formation in LITTLE THINGS Dwarf Irregular Galaxies - https://arxiv.org/abs/2512.10776 - arXiv:2512.10776v1 Announce Type: new -Abstract: The surface densities of star formation, Sigma_SFR, in 24 dwarf irregular (dIrr) galaxies from the LITTLE THINGS survey are combined with gas surface densities and midplane pressures to examine the correlations found previously for spiral galaxies. The pressure is the weight of the disk inside the gas layer, including gas, stars, and dark matter, which usually dominates disk gravity in dIrrs. We compare the results to the outer part of M33, which has similar local properties but a slightly higher metallicity, enabling the detection of CO. All the data are convolved to the HI beam, but to study the effects of resolution, the galaxies are examined first with average radial profiles, and then with maps having 1.5" pixels and 244 pc pixels. The correlations are found to be independent of resolution from 24 pc to 424 pc. The average ratio of molecular to atomic surface density is estimated to be 0.23+-0.1, from the H_2 surface density in M33 compared to the HI surface density at the same Sigma_SFR in the dIrrs. With this ratio, the average star formation rate per molecule is about the same for all the dIrrs, and a factor of 2 less than the rate in M33. The pressure in dIrrs is so low that CO is essentially a dense gas tracer, with the same surface density threshold at the low metallicities of dIrrs as HCN has in spiral galaxies. As a result, CO regions in dIrrs should be strongly self-gravitating. - oai:arXiv.org:2512.10776v1 + Hydrodynamic Evolution and Detectability of Nova Remnants in the Galactic Center + https://arxiv.org/abs/2512.16316 + arXiv:2512.16316v1 Announce Type: new +Abstract: Thousands of X-ray sources have been detected in the Galactic center (GC), most believed to be cataclysmic variables (CVs). As a potential probe of the old stellar population, in particular CVs, the existence and detectability of novae in the GC remain elusive, due to the prohibitive extinction toward the GC and their relatively low occurrence rate. Nova remnants evolving in the characteristic hot ($T\sim{10^{6}~\rm K}$) and dense ($n_e\sim{10~\rm cm^{-3}}$) interstellar medium in the GC may shed light on recent novae and provide useful insight on the GC ecosystem. In this work, we perform hydrodynamical simulations of putative nova remnants in the GC environment and calculate their time-dependent multiwavelength emission to estimate the detectability. Among 79 models sampling the nova parameter space (primarily ejecta mass and velocity), 6, 44, and 51 modelled nova remnants are detectable at their X-ray, radio, and Paschen-$\alpha$ maximum, respectively, for existing {\it Chandra}, VLA, and HST observations of the GC. The predicted peak luminosities are $\sim10^{32}~\rm erg~s^{-1}$, $\sim10^{31}~\rm erg~s^{-1}$, and $\sim10^{36}~\rm erg~s^{-1}$ in these three bands and the detectable window ranges from weeks to notably hundred years. By specifying a CV population of the nuclear star cluster, we estimate the probability of detecting at least one remnant to be 20\%, 8\%, and 18\% in X-rays, radio, and Pa$\alpha$. The nova remnant would be best resolved in the X-ray band. Our study highlights the potential for detecting nova remnants through further observations, leveraging JWST and the potentially forthcoming AXIS and SKA. + oai:arXiv.org:2512.16316v1 + astro-ph.HE astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Bruce G. Elmegreen, Deidre A. Hunter, Edvige Corbelli + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Zhao Su, Zhiyuan Li - Reaching diffraction-limited localization with coherent PTAs - https://arxiv.org/abs/2512.10795 - arXiv:2512.10795v1 Announce Type: new -Abstract: Current pulsar timing array (PTA) analyses do not take full advantage of pulsar distance information, thereby missing out on improved angular resolution and on a potential factor-of-two gain in detection sensitivity for individual gravitational-wave (GW) sources. In this work, we investigate the impact of precise pulsar distance measurements on angular resolution as an extension to previous work measuring the angular resolution of a dense, isotropic PTA [Jow et al., 2025]. We present a coherent map-making technique that utilizes precise pulsar distance measurements to reach the diffraction-limited resolution of an individual source: $\delta \theta_{\mathrm{diff}} \sim (1/\mathrm{SNR})(\lambda_{\mathrm{GW}}/r) \approx 2~\mathrm{arcmin}$, where the SNR refers to the detection strength of the source. With this level of angular resolution, identifying an EM counterpart may become feasible, enabling multi-messenger follow-up. We show that for $\rm SNR=10$, which may be the current sensitivity level using a coherent analysis, the diffraction limit is reached with roughly 9 pulsars. Moreover, angular resolution scales sharply with the number of known pulsar distances as $\sim (1/\mathrm{SNR})^{N_{\mathrm{dist}}/2}$. Thus, each additional pulsar with high signal-to-noise timing and precise distance measurement can improve PTA resolution by an order of magnitude. The distance to the best-timed millisecond pulsar (PSR J0437$-$4715) is already constrained to sub-parsec levels. We argue, therefore, that a coherent analysis of PTA data, fully incorporating pulsar distance information, is timely. - oai:arXiv.org:2512.10795v1 + New methods to improve the decontamination of slitless spectra + https://arxiv.org/abs/2512.16324 + arXiv:2512.16324v1 Announce Type: new +Abstract: This paper proposes four new methods to decontaminate spectra of stars and galaxies resulting from slitless spectroscopy used in many space missions such as Euclid. These methods are based on two distinct approaches and simultaneously take into account multiple dispersion directions of light. The first approach, called the local instantaneous approach, is based on an approximate linear instantaneous model. The second approach, called the local convolutive approach, is based on a more realistic convolutive model that allows simultaneous decontamination and deconvolution of spectra. For each approach, a mixing model was developed that links the observed data to the source spectra. This was done either in the spatial domain for the local instantaneous approach or in the Fourier domain for the local convolutive approach. Four methods were then developed to decontaminate these spectra from the mixtures, exploiting the direct images provided by photometers. Test results obtained using realistic, noisy, Euclid-like data confirmed the effectiveness of the proposed methods. + oai:arXiv.org:2512.16324v1 astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + math-ph + math.MP + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Anna C. Tsai, Dylan L. Jow, Ue-Li Pen + Mostafa Bella, Shahram Hosseini, Thierry Contini, Hicham Saylani - On the validity of the continuity equation in a modified gravity framework with CMB, DES 3x2pt and tomographic ISW data - https://arxiv.org/abs/2512.10802 - arXiv:2512.10802v1 Announce Type: new -Abstract: In this work we propose a phenomenological modification to the continuity equation at the linear perturbation level and test it using combinations of the CMB temperature, polarization and lensing potential angular spectrum, the ISW-galaxy cross power spectrum and the 3$\times$2pt lensing and galaxy clustering from DES survey. We investigate two parametrisations of this modification, both proportional to a new parameter $A_c$, which is assumed to be either constant in time, or proportional to the scale factor $a$, in order to be more relevant at late times. We find DES and ISW data to be consistent with the standard continuity equation when $A_c$ is constant, but 2--3$\sigma$ hints of a non-zero modification appear when Planck data is included. The model $A_c \propto a$ results in stronger tensions. We also test the effects of including the common extra parameters $\mu$ and $\eta$ that modify the Poisson equation and Weyl potential. Although $A_c$, $\mu$ and $\eta$ are correlated, we still find non-zero $A_c$ when Planck data is included or without Planck if $A_c \propto a$ and only either $\eta$ or $\mu$ are allowed to vary. We conclude that violations of the continuity equation should be considered with care when testing additional deviations from general relativity. - oai:arXiv.org:2512.10802v1 - astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + Maximizing the sensitivity of ELT to habitable worlds with a space-based starshade + https://arxiv.org/abs/2512.16361 + arXiv:2512.16361v1 Announce Type: new +Abstract: The ELT will provide groundbreaking science across a wide range of areas, including small habitable-zone exoplanets; however, true Earth analogs in the habitable zones of Sun-like stars are generally beyond the reach even of the ELT, due to the extreme contrast ratio and small angular separation between the planet and star. Here, we note that the combination of ELT and a space-based starshade would provide the contrast needed to observe potentially tens of Earth analogs, as well as other planets. This would yield the scientific basis needed for addressing central scientific questions regarding the frequency and distribution of habitability and life in the Universe. The huge aperture of ELT, combined with a contrast otherwise only reachable in space, opens up scientific avenues that are unmatched by any other existing or foreseen facility. ESO could conceivably collaborate with ESA (and others) to facilitate a starshade mission suitable for synergy with the ELT, as well as to prepare the ELT instrumentation in order to maximize its potential for synergy with a starshade. + oai:arXiv.org:2512.16361v1 + astro-ph.IM + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Ziad Sakr, Miguel Quartin + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Markus Janson, Enric Palle, Thomas Henning, Sascha Quanz, Lars Buchhave, Alexis Brandeker + + + Observational methods for solar origin diagnostics of energetic protons + https://arxiv.org/abs/2512.16362 + arXiv:2512.16362v1 Announce Type: new +Abstract: The aim of the present report is to outline the observational methods used to determine the solar origin - in terms of flares and coronal mass ejections (CMEs) - of the in situ observed solar energetic protons. Several widely used guidelines are given and different sources of uncertainties are summarized and discussed. In the present study, a new quality factor is proposed as a certainty check on the so-identified flare-CME pairs. In addition, the correlations between the proton peak intensity and the properties of their solar origin are evaluated as a function of the quality factor. + oai:arXiv.org:2512.16362v1 + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + 120 years Astronomical Observatory, Sofia University 'St. Kliment Ohridski' - 2017 + Rositsa Miteva - A remarkable Gaia-assisted discovery of a temporally varying, triple-lensed quasar at z=2.67 - https://arxiv.org/abs/2512.10811 - arXiv:2512.10811v1 Announce Type: new -Abstract: Gravitationally lensed quasars are viable cosmic tools for constraining a diversity of fundamental astrophysical phenomena; They enable identification of faint, low-mass supermassive black holes, provide unique constraints on the intervening intergalactic or interstellar medium in their sightlines, and can be used to determine key cosmological quantities such as the Hubble constant, $H_0$. However, they are rare phenomena, and it has proven difficult to define efficient, unbiased selection methods.} In this study, we report the spectroscopic identification of a remarkable triple-lensed quasar system at $z=2.67$, identified based on its astrometric measurements from the {\em Gaia} mission, as well as a larger spectroscopic follow-up survey of {\em Gaia}-detected candidate lensed quasars. We characterize in detail the three mirror images of the quasar and their spatial and temporal spectroscopic coverage, with focus on the emission-line properties which shows variation across sigthlines and temporal evolution over the $\sim 11$months spectroscopic campaign. We construct a lens model of the foreground source from a combination of the multiple spectra and deep optical imaging, providing a robust halo mass of $M_{\rm h} = (2.78 \pm 0.05)\times 10^{10}M_\odot$. Based on the lens model, the time delay between each sightline is translated into an intrinsic quasar time, allowing us to construct a quasar timeseries over $\sim18$months with monthly cadence. Over months timescales the broad emission lines vary in both velocity offset and equivalent width (EW) as well as an overall increase in ionization. This exemplary triple-lensed quasars demonstrates the viability of identifying such rare lens configurations based purely on the astrometric measurements from the {\em Gaia} mission, which we here provide optimized selection criteria for, for future studies. - oai:arXiv.org:2512.10811v1 + The AGN nature of strong CIII emitters in the Early Universe with JWST + https://arxiv.org/abs/2512.16365 + arXiv:2512.16365v1 Announce Type: new +Abstract: The semi-forbidden CIII] $\lambda\lambda$1907,1909 doublet is a key tracer of high-ionization emission in the early universe. We present a study of CIII] emission in galaxies at z=5-7, using publicly available JWST/NIRSpec prism data from programs including CEERS, JADES, RUBIES and CAPERS. We built a sample of 61 CIII]-emitting galaxies, and we classified them as star-forming or active galactic nuclei (AGN) host galaxies using (1) rest-frame UV and optical emission-line diagnostic diagrams, and (2) the presence/absence of broad Balmer emission lines. The UV diagnostics are based on the combination of the rest-frame equivalent width (EW) of CIII] versus CIII]/HeII $\lambda$1640, and the EW of CIV versus CIV/HeII $\lambda$1640. For optical diagnostics, we employ the OHNO diagram, which combines [OIII] $\lambda$5007, H$\beta$, [NeIII] $\lambda$3869, and [OII] $\lambda\lambda$3727,3729- and we find it has a low efficiency on separating AGN from SFG. We find that half of the sources in our sample (29 out of 61 galaxies) exhibit at least one secure indication of AGN activity while 13 are potential AGNs based on the CIII] diagnostic. Physical properties, including stellar mass and star formation rate, are derived through spectral energy distribution modeling with Bagpipes. Our analysis reveals that JWST is uncovering a population of strong CIII] emitters at high redshift (5<z<7) with a median EW of 22.8 A. This EW is higher than that of a control sample of CIII] emitters at redshift 3<z<4 with a median EW of 4.7 A. We find that for the same range of Muv, the CIII] EW increases by $\sim$0.67 dex from 3<z<4 to 5<z<7, indicating strong redshift evolution in the line's strength. Finally, we identify five sources in our sample as Little Red Dots (LRDs); while four of these have already been identified as LRD in the literature, one is presented here for the first time. + oai:arXiv.org:2512.16365v1 astro-ph.GA - astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + F. Arevalo-Gonzalez, R. Tripodi, M. Llerena, L. Pentericci, A. Plat, G. Barro, R. O. Amor\'in, B. Backhaus, A. Calabr\`o, N. J. Cleri, M. Dickinson, J. S. Dunlop, S. L. Finkelstein, M. Giavalisco, M. Hirschmann, J. Kartaltepe, A. M. Koekemoer, R. A. Lucas, L. Napolitano, E. Piconcelli, A. J. Taylor, F. Tombesi, J. R. Trump, X. Wang + + + High mass accretion rates onto evolved stripped-envelope massive stars by jet-induced mass removal + https://arxiv.org/abs/2512.16375 + arXiv:2512.16375v1 Announce Type: new +Abstract: Simulating one-dimensional stellar evolution models with MESA, we show that removing the outer inflated envelope of a mass-accreting evolved stripped-envelope star, like a Wolf-Rayet (WR) star, substantially moderates the stellar expansion during accretion at high-mass accretion rates. We study the accretion onto a star via an accretion disk, which launches jets that remove the high-entropy outer layers of the inflated envelope. This is the `jetted mass removal accretion scenario.' By manually removing the entire hydrogen-rich envelope from a red supergiant, we build a hydrogen-deficient WR stellar model with a mass of 6.03Mo and a radius of 0.67Ro. We then accrete mass onto it at a high rate. We mimic the real process of simultaneous mass addition near the equatorial plane and jet-induced mass removal from the outer envelope by dividing the accretion period into hundreds of pulses: in the first half of each pulse, we add mass, and in the second, we remove a fraction of this mass. The removal of tens of percent from the added mass decreases the stellar expansion by a factor of about 2-5. Our results show that WR stars can maintain a deep potential well and not expand much while accreting mass at high rates. This allows the formation of an accretion disk and the liberation of large amounts of gravitational energy. Our results strengthen models of intermediate-luminosity optical transients, such as luminous red novae, in which a non-degenerate star accretes at high rates and launches jets that power the transient event. + oai:arXiv.org:2512.16375v1 + astro-ph.SR + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Charlie Lind-Thomsen, Kasper E. Heintz, Albert Sneppen, Kostas Valeckas, Stefan Geier, Jens-Kristian Krogager, Johan Richard, Johan P. U. Fynbo + Yotham Cohen (Technion, Israel), Ealeal Bear (Technion, Israel), Noam Soker (Technion, Israel) - Resolving the ionizing photon budget crisis with JWST/NIRCam HII clumping constraints at z=6 - https://arxiv.org/abs/2512.10839 - arXiv:2512.10839v1 Announce Type: new -Abstract: We present a comprehensive study of the ionizing properties of 1721 galaxies at $5.6<z<6.5$ using deep JWST/NIRCam photometric imaging from the NEP, JADES, and PRIMER surveys spanning an unmasked area $\sim550$arcmin$^2$ across UV magnitudes $-22\lesssim M_{\rm UV}\lesssim-17.5$. Our $90\%$ stellar mass complete sample suggests little relation of UV slope with magnitude, $\beta_{\rm UV}=(-0.040\pm0.022)M_{\rm UV}-2.88^{+0.43}_{-0.44}$, implying $f_{\rm esc}^{\rm LyC}\simeq5\%$ based on calibrations from the Low-redshift Lyman Continuum Survey (LzLCS). We measure a constant ionizing photon production efficiency with UV magnitude, $\log_{10}(\xi_{\rm ion, 0}/\rm Hz\,erg^{-1}) = -0.006^{+0.019}_{-0.017}~M_{\rm UV} + 25.05^{+0.39}_{-0.34}$, consistent with HST canonical values. The total production rate of photons escaping into the IGM is computed as $\log_{10}(\dot{n}_{\rm ion}/\rm s^{-1}Mpc^{-3})=50.31^{+0.07}_{-0.06}$ for $M_{\rm UV}<-17$ galaxies from our star forming and smouldering UV luminosity functions (UVLFs), which differ in the faint-end slope ($\alpha_{\rm SFG}=-2.2\pm0.2$; $\alpha_{\rm sm}=-1.7\pm0.2$). Extrapolating to the latest UVLF turnover limits from the massive lensing galaxy cluster Abell S1063 ($M_{\rm UV, lim}=-13.5$) implies that a recombination-weighted HII clumping factor $C_{\rm HII, rec}=6.2^{+4.1}_{-2.1}$ is required to produce fully stably reionized at $z\simeq6$. A clumping factor of this magnitude resolves the ionizing photon budget crisis. Our methodology paves the way for indirect clumping measurements from galaxies which will provide insight into earlier stages of the EoR when the Ly$\alpha$-forest becomes saturated and more direct quasar measurements become impossible. - oai:arXiv.org:2512.10839v1 + Transformational astrophysics and exoplanet science with Habitable Worlds Observatory's High Resolution Imager + https://arxiv.org/abs/2512.16416 + arXiv:2512.16416v1 Announce Type: new +Abstract: Habitable Worlds Observatory (HWO) will be NASA's flagship space telescope of the 2040s, designed to search for life on other planets and to transform broad areas of astrophysics. NASA are seeking international partners, and the UK is well-placed to lead the design and construction of its imaging camera - which is likely to produce the mission's most visible public impact. Early participation in the mission would return investment to UK industry, and bring generational leadership for the UK in space science, space technology, and astrophysics. + oai:arXiv.org:2512.16416v1 + astro-ph.IM + astro-ph.EP astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Vincent Van Eylen, Richard Massey, Saeeda Awan, Jo Bartlett, Louisa Bradley, Andrei Bubutanu, Kan Chen, Andrew Coates, Mark Cropper, Ross Dobson, Fabiola Antonietta Gerosa, Emery Grahill-Bland, Leah Grant, Daisuke Kawata, Tom Kennedy, Minjae Kim, Adriana Adelina Mihailescu, Jan-Peter Muller, Georgios Nicolaou, Mathew Page, Paola Pinilla, Louisa Preston, Ted Pyne, Hamish Reid, Santiago Velez Salazar, Jason L. Sanders, Giorgio Savini, Ralph Schoenrich, George Seabroke, Alan Smith, Philip J. Smith, Nicolas Tessore, Marina Ventikos, Esa Vilenius, Francesca Waines, Silvia Zane, James Betts, Sownak Bose, Cyril Borgsom, Shaun Cole, Jessica E. Doppel, Vincent Eke, Carlos Frenk, Leo W. H. Fung, Qiuhan He, Mathilde Jauzac, Owen Jessop, Zane Deon Lentz, Gavin Leroy, Simon Morris, Yuan Ren, Jurgen Schmoll, Ray Sharples, Fionagh Thomson, Maximilian von Wietersheim-Kramsta, Kai Wang, Stephane V. Werner, Subhajit Sarkar, Jacob Kegerreis, James Kirk, Subhanjoy Mohanty, John Southworth, John Philip Stott, Ashley King, James W. Nightingale, David Rosario, Paola Tiranti, Edward Gillen, Cynthia S. K. Ho, Christopher Watson, Andrzej Fludra, Chris Pearson, Yun-Hang Cho, Yu Tao, Joanna Barstow, James Bowen, Chris Castelli, Chiaki Crews, Angaraj Duara, Mark Fox-Powell, David Hall, Carole Haswell, Kit-Hung Mark Lee, Joan Requena, Anabel Romero, Jesper Skottfelt, Konstantin Stefanov, Olivia Jones, Sean McGee, Annelies Mortier, Graham P. Smith, Amalie Stokholm, Amaury Triaud, Becky Alexis-Martin, Malcolm Bremer, Katy L. Chubb, Joshua Ford, Ben Maughan, Daniel Valentine, Hannah Wakeford, Juan Paolo Lorenzo Gerardo Barrios, Chandan Bhat, Xander Byrne, Gregory Cooke, Natalie B. Hogg, Nikku Madhusudhan, Maximilian Sommer, Sandro Tacchella, Georgios N. Vassilakis, Nicholas Walton, Mark Wyatt, Manoj Joshi, Beth Biller, Mariangela Bonavita, Trent Dupuy, Aiza Kenzhebekova, Brian P. Murphy, Vincent Okoth, Cyrielle Opitom, Larissa Palethorpe, Paul Palmer, Mia Belle Parkinson, Ken Rice, Sarah Rugheimer, Colin Snodgrass, Ben J. Sutlieff, Souradeep Bhattacharya, Emma Curtis-Lake, Jan Forbrich, Darshan Kakkad, David J. Lagattuta, Brian Ongeri Momanyi Bichang'a, Peter Scicluna, Richard Booth, Martin Barstow, Sarah Casewell, Leigh Fletcher, Anushka Sharma, Christopher J. Conselice, Suzanne Aigrain, Jayne Birkby, Claire Guimond, Carly Howett, Mei Ting Mak, Richard Palin, Chris Pattison, Richard Robinson, Samantha Youles, Andrew Collier Cameron, Justin Read, David John Armstrong, David J. A. Brown, Mikkel N. Lund, Andrew Robertson, Pierre-Olivier Lagage, L\'igia F. Coelho, Preethi R. Karpoor, Enric Palle, Leen Decin, Denis Defr\`ere, Kaustubh Hakim, Swara Ravindranath, Jason Rhodes, Marc Postman, Iain Neill Reid, Fabien Malbet, Amirnezam Amiri, Marrick Braam, Qiuhan He, Haakon Dahle, Angharad Weeks + + + Understanding the chemistry of temperate exoplanets atmospheres through experimental and numerical simulations + https://arxiv.org/abs/2512.16421 + arXiv:2512.16421v1 Announce Type: new +Abstract: Characterizing temperate exoplanet atmospheres remains challenging due to their small size and low temperatures. Recent JWST observations provide valuable data, but their interpretation has led to diverging conclusions. Complementary approaches combining laboratory experiments and photochemical modeling are essential for constraining atmospheric chemistry and interpreting observations. We aim to identify chemical pathways governing the formation and evolution of neutral species and to assess their sensitivity to key parameters such as C/O ratio and metallicity. Our approach combines experimental and numerical simulations on H2-rich gas mixtures representative of sub-Neptune atmospheres, spanning a wide range of CH4, CO, and CO2 mixing ratios. A cold plasma reactor simulates out-of-equilibrium upper-atmospheric chemistry. A 0D photochemical model reproduces reactor conditions, guiding interpretation of key pathways and abundance trends. We observe the formation of both reduced and oxidized organic compounds. In CH4-rich mixtures, hydrocarbons form efficiently through methane chemistry, correlating with CH4 concentration and agreeing with models. In more oxidizing environments, particularly CO2-rich mixtures, hydrocarbon formation is inhibited by complex reaction networks and oxidative losses. Oxygen incorporation enhances chemical diversity and promotes formation of oxidized organic compounds of prebiotic interest (H2CO, CH3OH, CH3CHO), especially in atmospheres containing both CH4 and CO2. Atmospheres containing CH4 and CO, which balance carbon and oxygen supply without excessive oxidative destruction, favor efficient production of hydrocarbons and oxidized compounds. Out-of-equilibrium chemistry plays a key role in the diversification and organic complexification of temperate exoplanet atmospheres. + oai:arXiv.org:2512.16421v1 + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + O. Sohier, A. Y. Jaziri, L. Vettier, A. Chatain, T. Drant, N. Carrasco + + + MUSE Analysis of Gas around Galaxies (MAGG) - VII. Emission line galaxies near strong blended Ly$\alpha$ absorption systems at $z\gtrsim3$ + https://arxiv.org/abs/2512.16422 + arXiv:2512.16422v1 Announce Type: new +Abstract: We investigate the connection between strong, blended Ly$\alpha$ absorption systems (SBLAs) and $\approx1000$ Ly$\alpha$ emitting galaxies (LAEs) at $z\gtrsim3$ in 28 quasar fields from the MUSE Analysis of Gas around Galaxies (MAGG) survey. Selecting SBLAs as spectral regions with transmitted flux $-0.05<F<0.25$ over $\approx138\text{ km s}^{-1}$ bins, we find a strong correlation with LAEs within a projected distance of $R\le300\rm\,kpc$ and line-of-sight velocity separation of $|\Delta v|\le300 \text{ km s}^{-1}$. The association rate increases significantly with decreasing flux, a trend that persists also at smaller separations ($R<100$ kpc). A two-dimensional cross-correlation analysis confirms significant clustering of LAEs around SBLAs, while no such clustering is seen for spectral regions with $F>0.25$. The correlation appears to also depend on the width of the spectral window used to identify SBLAs, with a larger window yielding a stronger signal. Our analysis confirms that SBLAs serve as probes of the CGM at the interface between the Ly$\alpha$ forest and the optically-thick Lyman limit systems. The significant dependence of the LAE-SBLA cross-correlation on the spectral binning used to select these absorbers motivates future tests of the current SBLA framework as a tracer of halos. + oai:arXiv.org:2512.16422v1 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Marta Galbiati, Davide Tornotti, Michele Fumagalli, Matteo Fossati, Matthew Pieri + + + A direction-dependent framework for visibility plane mosaicing and primary beam correction + https://arxiv.org/abs/2512.16440 + arXiv:2512.16440v1 Announce Type: new +Abstract: With the increasing sensitivity of modern radio interferometers, it has become important to image objects larger than the field of view while optimising sensitivity and image fidelity. We present a coherent visibility plane direction-dependent imaging, calibration and mosaicing framework. Our simulations and application to real MeerKAT data show that this joint deconvolution and primary beam correction approach, coupled with direction-dependent calibration, allows for deeper mosaics with greater fidelity and increased accuracy of recovered flux densities and spectral indices, especially beyond the half-power beam width. Our best-case mosaic produces precise flux values within a 6% uncertainty and spectral indices within 20\% throughout the imaged area, and is fully complete out to twice the radii and half the flux density than the image plane equivalent. The application to archival wideband MeerKAT 1283 MHz data produces the deepest high-resolution image of the Shapley Supercluster Core, with a sensitivity of 3.6 $\mu$Jy/beam within the primary beam at a 7$^{\prime\prime}$ resolution, constituting a $\sim$ 50% increase in dynamic range over the image plane counterpart, and a fluxscale that is consistent within 10% across the entire field of view. The compute time for the direction-dependent visibility plane mosaic was comparable to the sum of the times needed to perform direction-dependent calibration on the individual pointings. Our results suggest that visibility plane mosaicing with its capability for deeper deconvolution could improve the efficiency of deep and wide surveys, particularly for on-the-fly mapping and studies of low surface brightness sources, and could form the basis of future calibration pipelines for SKA-scale instruments. + oai:arXiv.org:2512.16440v1 + astro-ph.IM + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Keegan S. Trehaeven, Cyril Tasse, Oleg Smirnov, Tiziana Venturi + + + Classification of the equation of state of neutron stars via sparse dictionary learning + https://arxiv.org/abs/2512.16441 + arXiv:2512.16441v1 Announce Type: new +Abstract: The post-merger phase of binary neutron star (BNS) mergers encodes valuable information about the equation of state (EOS) of supranuclear matter. Extracting this information from the analysis of the post-merger waveforms remains challenging due to the high-frequency limitations of current detectors. Future third-generation observatories, such as the Einstein Telescope (ET) and NEMO, will have the sensitivity required to resolve post-merger signals with high fidelity. In this work, we apply CLAWDIA, our recently developed sparse dictionary learning (SDL) framework, to classify different EOS models using only the post-merger gravitational-wave emission of simulated BNS mergers available in the CoRe database. Our dataset comprises five EOS models representative of a broad range of neutron star properties. The SDL framework is optimised under realistic detection conditions by injecting signals into simulated noise matching the sensitivity curves of ET and NEMO. Our results show that classification is primarily driven by the dominant post-merger frequency, $f_2$, which encodes EOS-dependent information. At a modest signal-to-noise ratio of 5, our method achieves $F_1$ scores of $0.76$ for ET and $0.70$ for NEMO, with performance improving for higher signal-to-noise ratios. The reliability and generalisation capabilities of the model are assessed with additional tests, including the classification of an EOS not included in the training dataset and the analysis of detector-specific biases. + oai:arXiv.org:2512.16441v1 + astro-ph.HE + gr-qc + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Miquel Llorens-Monteagudo, Alejandro Torres-Forn\'e, Jos\'e A. Font + + + Uniform Rolling: An LSST Observing Cadence Offering Sufficient Survey Uniformity for Comprehensive Cosmological Analysis + https://arxiv.org/abs/2512.16478 + arXiv:2512.16478v1 Announce Type: new +Abstract: The Legacy Survey of Space and Time (LSST) that will be carried out by the NSF-DOE Vera C. Rubin Observatory promises to be the defining survey of the next decade, supplying unprecedented access to the night sky to static science- and time-domain science-focused researchers alike. Maximizing the output of the broad remit of Rubin Observatory science requires a non-trivial survey strategy. For time-domain science, the most promising strategy designed so far is a rolling survey strategy, whereby a subset of the full LSST survey area is observed at higher rate compared with the nominal rate dictated by weather conditions and the observatory's technical constraints. This strategy is now the baseline approach for the LSST as a whole. Focusing on static science (galaxy clustering and weak lensing), we study how these time-domain-optimized rolling strategies affect the depth uniformity at intermediate years of the survey. We characterize the amount of survey area at high risk of being lost in static-science analyses of a baseline rolling LSST dataset due to an insufficient combination of survey contiguity and uniformity. At intermediate data releases, nearly half of the survey could be lost for static science, decreasing the Dark Energy figure of merit by approximately 40\%. We describe additional metrics focused on key analysis tasks, such as photometric redshifts and galaxy clustering. We propose a new strategy that returns the survey to uniformity at key release years, enabling use of the full survey area and restoring our metrics to the values they would have in a non-rolling cadence without loss of time domain data relative to a rolling survey with the same number of rolling cycles. This work has informed the third round of optimization of the survey strategy, and the new uniform rolling strategies have been incorporated into the baseline strategy. + oai:arXiv.org:2512.16478v1 astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.IM + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Duncan Austin, Thomas Harvey, Christopher J. Conselice, Nathan J. Adams, Vadim Rusakov, Qiong Li, Lewi Westcott, Caio Goolsby, Kai Madgwick, James Arcidiacono, Massimo Ricotti, Sophie L. Newman, Louise T. C. Seeyave, James Trussler, Brenda Frye, Norman A. Grogin, Rolf A. Jansen, Anton M. Koekemoer, Nor Pirzkal, Michael Rutkowski, Rogier A. Windhorst + http://creativecommons.org/licenses/by/4.0/ + Boris Leistedt, Matthew R. Becker, Humna Awan, Eric Gawiser, Qianjun Hang, Ren\'ee Hlo\v{z}ek, Saurabh W. Jha, R. Lynne Jones, Arun Kannawadi, Michelle Lochner, Rachel Mandelbaum, Jeffrey A. Newman, I. Sevilla-Noarbe, Hiranya V. Peiris, Eli S. Rykoff, M. A. Troxel, Peter Yoachim - Inflation in light of ACT/SPT: a new perspective from Weyl gravity - https://arxiv.org/abs/2512.10862 - arXiv:2512.10862v1 Announce Type: new -Abstract: Recent measurements from the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT) have placed the strictest constraints on the primordial scalar perturbation spectrum, reporting a spectral index of $n_s\sim0.967-0.98$ at 95% confidence level. This result indicates a stronger scale invariance of the scalar perturbation than earlier estimates, posing challenges for numerous inflation models. In this work, we propose an appealing inflationary scenario from the Weyl scale-invariant gravity theory dominated by the higher-order curvatures. Specifically, the exponential curvature extensions are introduced to suppress the mass divergence of the inflaton. We find such scenario naturally yields leading-order predictions of $n_s\simeq1-3/(2N)\sim0.97-0.975$ or $n_s\simeq1-5/(3N)\sim0.967-0.972$ for various models, in excellent agreement with the ACT/SPT constraints. This result builds a concrete bridge between theoretical and observational scale invariance, implying an enduring cosmic echo of the primordial symmetry. - oai:arXiv.org:2512.10862v1 + How massive neutrinos reshape the cosmic web + https://arxiv.org/abs/2512.16517 + arXiv:2512.16517v1 Announce Type: new +Abstract: We explore the effects of massive neutrinos on the cosmic web using the FLAMINGO simulations. We classify the cosmic web into voids, sheets, filaments, and clusters, and find that massive neutrinos affect the environment by decreasing the volume occupied by clusters and voids. We find that increasing the neutrino mass shifts the volume-weighted density distribution towards higher densities and leads to a more narrow density distribution, which we interpret as neutrinos delaying structure formation. We construct the minimum spanning tree (MST) graph from the subhaloes, adopting a number density chosen to match that expected for DESI-like observations. We show that most MST edges lie in filaments, approximately 70% throughout different simulations, which we link to its sensitivity to neutrino mass. We also link the MST's edge length signal at different scales to different cosmic web environments, with clusters dominating the signal at small scales, voids at longer scales, and filaments at intermediate scales. The strong correlation between MST edges and cosmic web environments reinforces the MST's potential to be used as a classifier for large-scale structure in galaxy surveys. We compare the effects of baryonic physics and massive neutrinos and find that each produces distinct signatures in MST edge lengths. This analysis is performed in 3D space, using the true positions of subhaloes and not accounting for redshift space distortions. Nevertheless, these results emphasise the MST's capability to go beyond two-point statistics, motivating future applications to real observational data. + oai:arXiv.org:2512.16517v1 astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Qing-Yang Wang + Leonor N. L. Sim\~oes, Krishna Naidoo, Benjamin Joachimi, Willem Elbers, Carlos S. Frenk - Diversity in the haziness and chemistry of temperate sub-Neptunes - https://arxiv.org/abs/2512.10876 - arXiv:2512.10876v1 Announce Type: new -Abstract: Recent transit observations of K2-18b and TOI-270d revealed strong molecular absorption signatures, lending credence to the idea that temperate sub-Neptunes (T$_\mathrm{eq}$=250-400K) have upper atmospheres mostly free of aerosols. These observations also indicated higher-than-expected CO$_2$ abundances on both planets, implying bulk compositions with high water mass fractions. However, it remains unclear whether these findings hold true for all temperate sub-Neptunes. Here, we present the JWST NIRSpec/PRISM 0.7-5.4$\mathbf{\mu}$m transmission spectrum of a third temperate sub-Neptune, the 2.4R$_\oplus$ planet LP 791-18c (T$_\mathrm{eq}$=355K), which is even more favorable for atmospheric characterization thanks to its small M6 host star. Intriguingly, despite LP 791-18c's radius, mass, and equilibrium temperature being in between those of K2-18b and TOI-270d, we find a drastically different transmission spectrum. While we also detect methane on LP 791-18c, its transit spectrum is dominated by strong haze scattering and there is no discernible CO$_2$ absorption. Overall, we infer a deep metal-enriched atmosphere (246-415$\times$solar) for LP 791-18c, with a CO$_2$-to-CH$_4$ ratio smaller than 0.07 (at 2$\sigma$), indicating less H$_2$O in the deep envelope of LP 791-18c and implying a relatively dry formation inside the water ice-line. These results show that sub-Neptunes that are near-analogues in density and temperature can show drastically different aerosols and envelope chemistry, and are intrinsically diverse beyond a simple temperature dependence. - oai:arXiv.org:2512.10876v1 - astro-ph.EP - Fri, 12 Dec 2025 00:00:00 -0500 + XMM-Newton multi-year campaign on NGC 55 ULX-1: Resolving the wind and its variability with RGS + https://arxiv.org/abs/2512.16522 + arXiv:2512.16522v1 Announce Type: new +Abstract: Winds are an important ingredient in the evolution of X-ray binary (XRB) systems, particularly those at high accretion rates such as ultra-luminous X-ray sources (ULXs), because they may regulate the accretion of matter onto the compact object. We aim at understanding the properties of ULX winds and their link with the source spectral and temporal behavior. We performed high-resolution X-ray spectroscopy of the variable source NGC 55 ULX-1 to resolve emission and absorption lines as observed with XMM-Newton at different epochs. Optically-thin plasma models are used to characterise the wind. We confirmed and thoroughly strengthened previous evidence of outflows in NGC 55 ULX-1. The presence of radiative recombination signatures and the ratios between the fluxes of the emission lines favours photoionisation balance and low-to-moderate densities, which confirm that the lines originate from classical XRB disc winds. An in-depth parameter space exploration shows line emission from a slowly moving, cool, and variable plasma perhaps associated with a thermal wind. Mildly-relativistic Doppler shifts (about -0.15c) associated with the absorption lines confirm, at higher confidence, the presence of powerful, radiatively-driven, winds. The comparison between results obtained at different epochs revealed that the wind responds to the variability of the underlying continuum and these variations may be used to understand the actual accretion regime and the nature of the source. + oai:arXiv.org:2512.16522v1 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 10.1038/s41550-025-02723-3 - Pierre-Alexis Roy, Bj\"orn Benneke, Marylou Fournier-Tondreau, Louis-Philippe Coulombe, Caroline Piaulet-Ghorayeb, David Lafreni\`ere, Romain Allart, Nicolas B. Cowan, Lisa Dang, Doug Johnstone, Adam B. Langeveld, Stefan Pelletier, Michael Radica, Jake Taylor, Lo\"ic Albert, Ren\'e Doyon, Laura Flagg, Ray Jayawardhana, Ryan J. MacDonald, Jake D. Turner + C. Pinto, S. Caserta, F. Barra, Y. Xu, D. Barret, P. Kosec, N. La Palombara, A. Marino, F. Pintore, A. Riggio, T. P. Roberts, C. Salvaggio, L. Sidoli, R. Soria, D. J. Walton + + + Pulsar B1237+25 at 111~MHz: average profile, mode switching, nullings, microstructure + https://arxiv.org/abs/2512.16526 + arXiv:2512.16526v1 Announce Type: new +Abstract: The observations of B1237+25 at a frequency of 111 MHz were analyzed. For the first time in the normal radiation mode a new component in the central region in the average profile was detected. This component is manifested in all modes of pulsar emission: quiet-normal (QN), flare-normal (FN) and in the abnormal mode (AB). The subpulse drift is observed in the QN mode only in the first and last components of the average profile. The normal mode is interrupted by nullings and transitions into the abnormal AB mode. In the AB mode, the structure at the edge of the outer cone is destroyed, the distance between the inner and outer cones is almost doubled, and the distance between the inner cone and the central region is reduced.Analysis of our data has shown that the components of the outer and inner cones of the average profile are formed by an ordinary mode of radio emission (O-mode) and form a single cone radiation of the pulsar. The central components of the average profile (wide and narrow) are formed by an extraordinary mode (X-mode). Estimates of the height of the radiation output from the central region (X-mode) and the cone radiation (O-mode) are obtained: 80~km and 370~km, respectively. A microstructure with a time scale of $\tau_\mu\le0.5$~$\mu s$ has been detected. This time scale corresponds well to the time of the development of a spark discharge in the polar cap. For this value $\tau_\mu$, the height of the vacuum gap should be $h_p\le750$~cm. Based on the steepness of the individual pulse's trailing edge at the longitude of the first component, a limit was obtained on the value of the $\gamma$ factor of the relativistic secondary plasma: $\gamma\ge$260. The dependence of the distance between the components of the outer and inner cone of radiation on the frequency is the same and corresponds to a power law with an exponent of -0.16. + oai:arXiv.org:2512.16526v1 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1134/S1063772925702087 + Astronomy Reports, 2025, vol 69, No 9, pp 819-833 + M. V. Popov, T. V. Smirnova - Weighing the Milky Way's Satellite Galaxies Using Pulsar Accelerations - https://arxiv.org/abs/2512.10883 - arXiv:2512.10883v1 Announce Type: new -Abstract: The properties of dwarf galaxies orbiting the Milky Way (MW) are useful for testing models of the formation of our Galaxy, and by extension various theories of cosmology. Recent efforts to measure the masses of the MW's satellite dwarf galaxies have relied on the motions and positions of stars in the MW's disk and halo, which are perturbed by the passage of satellite galaxies. As there are many known processes in our Galaxy that lead to observed disequilibrium in stars, these kinematic methods have been limited by the inherent difficulty in identifying only the perturbations due to particular satellite galaxies. We present a novel method for determining the masses of two MW satellite galaxies -- the Large Magellanic Cloud (LMC) and the Sagittarius Dwarf Spheroidal Galaxy (Sgr dSph) -- using only direct, instantaneous acceleration data derived from extremely precise timing of millisecond pulsars near the Sun. As the LMC and Sgr dSph orbit the MW, they cause wave-like distortions in the structure of the disk plus a large-scale offset in the centers of mass of the dark matter halo and the baryonic disk. These two effects lead to asymmetric accelerations above and below the disk midplane near the Sun, which is observed in the pulsar acceleration data. Notably, the amplitude of this asymmetry is shown to depend on the masses of the orbiting satellites. We analyze a grid of simulations with varying masses of each satellite. We find the total (dark + baryon) mass enclosed within the tidal radius at the present day for the LMC to be 4.1 $\pm$ 1.0 $\times$ 10$^{10}$ M$_\odot$ within a radius of 16.6 kpc, and for Sgr to be 3.5 $\pm$ 2.4 $\times$ 10$^8$ M$_\odot$ within a radius of 5 kpc. These results are generally consistent and competitive with previous determinations of the masses of these objects, but entirely independent of any stellar kinematic data for the first time. - oai:arXiv.org:2512.10883v1 + Galaxy evolution in compact groups - III. Structural analysis of galaxies and dynamical state of non-isolated compact groups + https://arxiv.org/abs/2512.16542 + arXiv:2512.16542v1 Announce Type: new +Abstract: Compact Groups (CGs) of galaxies are dense systems where projected separations are comparable to their optical diameters. A subset - non-isolated CGs - are embedded within major structures. Using multi-band S-PLUS data, we analyse galaxies in 122 non-isolated CGs within more massive systems such as larger groups and clusters. We compare them to galaxies in the host structures, hereafter surrounding group galaxies. Structural parameters were obtained with MorphoPLUS, a pipeline for multi-wavelength S\'ersic profile fitting. Dividing galaxies into early (ETG), transition, or late types (LTG), we find: (1) Non-isolated CGs host higher quenched fractions and more ETGs, especially for stellar masses $\log(M/M_\odot) > 10.2$, than surrounding groups. (2) S\'ersic indices increase with wavelength for all morphological types in both environments, whereas effective radii show a stronger morphology-dependent behaviour - ETGs become more compact towards redder bands, while LTGs exhibit flatter $Re(\lambda)$ trends. Environmental differences remain weak, with only a modest enhancement of the gradients for ETGs in non-isolated CGs. (3) Transition galaxies in CGs show a concentrated $R_e$-$n$ distribution and faint-end bimodality, consistent with ongoing morphological transformation absent in surrounding groups. (4) Phase-space analysis indicates that some CGs in clusters are projection artefacts, while others are genuine dense systems at various infall stages, from recent arrivals to ancient remnants. These results show that galaxies in non-isolated CGs follow distinct evolutionary paths compared to their surrounding groups galaxies, suggesting that the compact configuration plays a unique role beyond the influence of the larger-scale environment. + oai:arXiv.org:2512.16542v1 astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.3847/1538-4357/ae2bdd + Gissel P. Montaguth, Ana Laura O'Mill, Claudia Mendes de Oliveira, Ciria Lima-Dias, Sergio Torres-Flores, Antonela Monachesi, D. E. Olave-Rojas, Diego Pallero, Pedro K. Humire, Ricardo Demarco, Eduardo Telles, Paulo A. A. Lopes, Swayamtrupta Panda, Rodrigo F. Haack, Amanda R. Lopes, Alvaro Alvarez-Candal, Analia V. Smith Castelli, Antonio Kanaan, Tiago Ribeiro, William Schoenell + + + N-emitters as possible sign-posts of GC formation + https://arxiv.org/abs/2512.16549 + arXiv:2512.16549v1 Announce Type: new +Abstract: Based on the finding of unusual chemical abundance ratios of N-emitters, which resemble those of globular cluster (GC) stars, their compactness, high ISM densities and other properties, it has been suggested that N-emitters could indicate the formation sites of globulars. A recent statistical study of the N-emitter population has quantified the frequency $f_N$ of these rare objects and their redshift evolution (Morel et al. 2025). Using these results we here test if N-emitters trace the formation of GCs and use the observed cosmic star-formation rate density evolution to predict the cosmological evolution of the GC population with time, their age distribution, and the total present-day stellar mass density formed in globulars. The predicted age distribution of GCs strongly resembles the typical asymmetric observed distributions in the Galaxy and ellipiticals, with a peak at $\sim 11.5-12$ Gyr and a longer tail extending to younger ages. We derive a total stellar mass density formed in N-emitters down to redshift zero of $(2-7) \times 10^5$ M$_{\odot}$ Mpc$^{-3}$, which matches within a factor $\sim 2$ the observed fraction of stellar mass found in the GC population at $z=0$. These results provide additional indirect arguments supporting the hypothesis that N-emitters could represent sign-posts of a short phase of GC formation. + oai:arXiv.org:2512.16549v1 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Thomas Donlon II, Sukanya Chakrabarti, Jason A. S. Hunt + D. Schaerer, R. Marques-Chaves, H. Atek, N. Prantzos, C. Charbonnel, M. Talia, I. Morel, M. Dessauges-Zavadsky - Impact of geometry on 1D molecular-kinetics simulations of acoustic-gravity wave propagation into the exosphere - https://arxiv.org/abs/2512.10887 - arXiv:2512.10887v1 Announce Type: new -Abstract: Direct Simulation Monte Carlo (DSMC) calculations of acoustic gravity wave propagation into the exobase region of a Mars-like atmosphere reveal that radial geometry can reduce wave-driven heating compared to a Cartesian model. We examine two acoustic wave (AW) modes with periods of 11 minutes (AW1) and 5.5 minutes (AW2) propagating from 100 to 320 km altitude using a radial molecular kinetics model. The wave-driven heating was reduced by 40-56% with cycle-averaged temperature gradient $\langle dT/dr \rangle$ decreasing from 9.4 K per scale height H0 to 5.6 K/H$_0$ for AW1 and from 4.4 K/H$_0$ to 1.9 K/H$_0$ for AW2 when accounting for planetary curvature. While the growth in wave density amplitude was attenuated for the 1D radial geometry as well, the heating differences are more pronounced, with both effects driven by geometric spreading accumulating as waves propagate into increasingly rarefied regions. These findings suggest that accounting for curvature effects is crucial when conducting DSMC estimates of acoustic wave contributions to thermospheric heating and atmospheric escape, as Cartesian-based derived counterparts may be overestimated by factors of 1.7-2.3 for these frequencies. - oai:arXiv.org:2512.10887v1 + Warm Jupiter Tidal Migration Can Spare Inner Planets; Hot Jupiter Tidal Migration May Not + https://arxiv.org/abs/2512.16550 + arXiv:2512.16550v1 Announce Type: new +Abstract: In this work, we investigate the dynamical survival of short-period inner planets during the high-eccentricity tidal migration of companion exterior giant planets. Using a combination of analytic arguments and N-body simulations including equilibrium tides and general relativistic precession, we find the boundary in parameter space where an inner companion can remain dynamically stable. We find that survival requires a periastron separation exceeding roughly 14 mutual Hill radii at closest approach. Below this threshold, secular eccentricity exchange, orbit crossing, and/or tidal evolution can lead to the destruction of the inner planet. We apply our methodology to the current exoplanet sample and find that none of the known systems containing a short-period giant and an inner companion could have assembled via high-eccentricity tidal migration. However, warm Jupiters with larger periastron distances ($q_{\mathrm{out}} \sim 0.05-0.08$ AU, corresponding to final observed semi-major axis values $a_{\mathrm{out}} \sim 0.10-0.16$ AU) can allow the survival of short-period inner planets while potentially also circularizing on $\lesssim 1$ Gyr timescales. Our results provide a framework for distinguishing disk migration from tidal migration in observed multi-planet systems containing close-in gas giants. + oai:arXiv.org:2512.16550v1 astro-ph.EP - physics.ao-ph - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - 10.1016/j.icarus.2025.116900 - Icarus, 447 (2026), 116900 - Jose A. Perez Chavez, Orenthal J. Tucker, Shane R. Carberry Mogan, Robert E. Johnson, Christopher Blaszczak-Boxe + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Juliette Becker + + + Decoupling perturbations from background in $f(Q)$ gravity: the square-root correction and the alleviation of the $\sigma_8$ tension + https://arxiv.org/abs/2512.16551 + arXiv:2512.16551v1 Announce Type: new +Abstract: We investigate a perturbation-level modification of symmetric teleparallel gravity of the form $f(Q)=F(Q)+M\sqrt{Q}$ and assess its ability to ease the $\sigma_8$ tension. The square-root term leaves the background expansion unchanged while modifying the effective gravitational coupling, providing a pure decoupling between background cosmology and structure-growth evolution. Using the latest redshift-space distortion data, including DESI DR2 Full-Shape measurements, we constrain $M$ and $\sigma_8$ across three representative backgrounds: $\Lambda$CDM, an $H_0$-tension-reducing model, and a DESI-motivated dynamical dark energy scenario. In all cases, the square-root correction suppresses growth and can reconcile $\sigma_8$ with Planck at the $1\sigma$ level, with the strongest improvement occurring in the $H_0$-tension-oriented background. A residual degeneracy between $M$ and $\sigma_8$ remains, indicating that future multi-probe analyses combining lensing and full-shape clustering will be required to determine whether the $\sqrt{Q}$ term represents a genuine signal of modified gravity. + oai:arXiv.org:2512.16551v1 + astro-ph.CO + gr-qc + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Chunyu Li, Xin Ren, Yuhang Yang, Emmanuel N. Saridakis, Yi-Fu Cai - The LISA Astrophysics "Disc-IMRI" Code Comparison Project: Intermediate-Mass-Ratio Binaries in AGN-Like Discs - https://arxiv.org/abs/2512.10893 - arXiv:2512.10893v1 Announce Type: new -Abstract: Upcoming space-based gravitational wave detectors such as LISA, the Laser Interferometer Space Antenna, will be sensitive to extreme- and intermediate-mass-ratio inspirals (EMRIs and IMRIs). These binaries are comprised of a supermassive black hole and a stellar-mass object or intermediate-mass black hole. Their detection will probe the structure of galactic nuclei and enable tests of general relativity. As these events will be observed over thousands of orbital cycles, they will be extremely sensitive to both the underlying spacetime and astrophysical environment, demanding exquisite theoretical models on both fronts to avoid biased or even erroneous results. In particular, many (E/)IMRIs are expected to occur within accretion discs around supermassive black holes, and the nonlinearities present when modeling these systems require numerical simulations. In preparation for future modeling of LISA sources, we have conducted a comparison between eight different hydrodynamical codes and applied them to the problem of a q = 10^{-4} mass ratio binary interacting with an accretion disc. Thicker discs appear more lenient, and all codes at sufficiently high resolutions are in good agreement with each other and analytical predictions. For thinner discs, beyond the reach of analytical models, we find substantial disagreement between 2D and 3D simulations and between different codes, including both the magnitude and sign of the torque. With time and energy efficiency in mind, codes that leverage moving meshes or grid-based Lagrangian remapping seem preferable, as do codes that can leverage graphical processing units and other energy-efficient hardware. - oai:arXiv.org:2512.10893v1 + Double shell structure in supernova 2024ggi + https://arxiv.org/abs/2512.16554 + arXiv:2512.16554v1 Announce Type: new +Abstract: We built a simple toy model of a core-collapse supernova (CCSN) ejecta composed of two shells, an outer low-mass spherical shell and an inner elongated massive shell, and show that it can reproduce the evolution of the photospheric radius of SN 2024ggi, Rph(t). During the first week, the larger spherical shell, the S-shell, forms the photosphere. As the shell expands and becomes increasingly transparent, the photosphere moves inward along the mass coordinate, although it grows in size. When the photosphere reaches the long axis of the elongated inner shell, the E-shell begins to contribute to the photosphere, ultimately comprising the entire photosphere. The simple toy model explains the transition of Rph(t) from being concave (decreasing slope) to convex (increasing slope). A single-shell model predicts only concave behavior. The structure of a spherical shell with an inner elongated shell is motivated by the morphologies of several CCSN remnants whose structures have been attributed to multiple pairs of jets in the framework of the jittering jets explosion mechanism (JJEM). The deduced multiple-shell ejecta of SN 2024ggi in this study, and of SN 2023ixf in an earlier study, as well as studies of the polarization of SN 2024ggi, are better compatible with the JJEM than with the neutrino-driven mechanism. Our study supports the growing evidence that the JJEM is the primary explosion mechanism of CCSNe. + oai:arXiv.org:2512.16554v1 astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Andrea Derdzinski, Alexander J. Dittmann, Alessia Franchini, Alessandro Lupi, No\'e Brucy, Pedro R. Capelo, Fr\'ed\'eric S. Masset, Rapha\"el Mignon-Risse, Michael Rizzo Smith, Edwin Santiago-Leandro, Martina Toscani, David A. Velasco-Romero, Robert Wissing, Mudit Garg, Lucio Mayer, Roberto Serafinelli, Lazaros Souvaitzis, Daniel J. D'Orazio, Jonathan Menu + Kobi Shiran (Technion, Israel), Noam Soker (Technion, Israel) - Updated and Projected Cosmic Microwave Background Bounds on WIMP Annihilation - https://arxiv.org/abs/2512.10896 - arXiv:2512.10896v1 Announce Type: new -Abstract: We derive updated Cosmic Microwave Background (CMB) constraints on annihilating dark matter, and present forecasts for upcoming CMB surveys. We show that the addition of recent temperature, polarization, and lensing data from ground-based experiments yields only minor improvements ($\approx 10\%$) compared to Planck bounds, confirming that the sensitivity remains dominated by the large-scale E-mode polarization. Forecasts, using a LiteBIRD-like setup, indicate that pairing a low-noise, wide-sky satellite at $\ell < 200$ with high-resolution ground observations nearly saturates the cosmic-variance limit, improving bounds by $\approx 60\%$, where our derived 95th percentile limit is $p_{\rm ann} < 1.27{\times}10^{-28}\,\mathrm{cm^{3}\,s^{-1}\,GeV^{-1}}$. We also consider the inclusion of B-mode polarization for a realistic future experiment. - oai:arXiv.org:2512.10896v1 - astro-ph.CO - hep-ph - Fri, 12 Dec 2025 00:00:00 -0500 + Prompt Searches for Very-High-Energy {\gamma}-Ray Counterparts to IceCube Astrophysical Neutrino Alerts + https://arxiv.org/abs/2512.16562 + arXiv:2512.16562v1 Announce Type: new +Abstract: The search for sources of high-energy astrophysical neutrinos can be significantly advanced through a multi-messenger approach, which seeks to detect the gamma rays that accompany neutrinos as they are produced at their sources. Multi-messenger observations have so far provided the first evidence for a neutrino source, illustrated by the joint detection of the flaring blazar TXS 0506+056 in highenergy (HE, E > 1 GeV) and very-high-energy (VHE, E > 100 GeV) gamma rays in coincidence with the high-energy neutrino IceCube-170922A, identified by IceCube. Imaging atmospheric Cherenkov telescopes (IACTs), namely FACT, H.E.S.S., MAGIC, and VERITAS, continue to conduct extensive neutrino target-of-opportunity follow-up programs. These programs have two components: followup observations of single astrophysical neutrino candidate events (such as IceCube-170922A), and observation of known gamma-ray sources after the identification of a cluster of neutrino events by IceCube. Here we present a comprehensive analysis of follow-up observations of high-energy neutrino events observed by the four IACTs between September 2017 (after the IceCube-170922A event) and January 2021. Our study found no associations between gamma-ray sources and the observed neutrino events. We provide a detailed overview of each neutrino event and its potential counterparts. Furthermore, a joint analysis of all IACT data is included, yielding combined upper limits on the VHE gamma-ray flux. + oai:arXiv.org:2512.16562v1 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Charlotte Myers, Dominic Agius, Daniele Gaggero, Angelo Ricciardone + 10.3847/1538-4357/ae2c4e + J. Abhir, A. Biland, K. Brand, T. Bretz, D. Dorner, L. Eisenberger, D. Elsaesser, P. G\"unther, S. Hasan, D. Hildebrand, K. Mannheim, M. Linhoff, F. Pfeifle, W. Rhode, B. Schleicher, V. Sliusar, M. Vorbrugg, R. Walter, F. Aharonian, F. Ait Benkhali, J. Aschersleben, H. Ashkar, M. Backes, V. Barbosa Martins, R. Batzofin, Y. Becherini, D. Berge, M. B\"ottcher, C. Boisson, J. Bolmont, J. Borowska, R. Brose, A. Brown, F. Brun, B. Bruno, S. Casanova, J. Celic, M. Cerruti, A. Chen, M. Chernyakova, J. Chibueze, O. Chibueze, B. Cornejo, G. Cotter, G. Cozzolongo, J. Damascene Mbarubucyeye, J. de Assis Scarpin, A. Delgado Giles, A. Djannati-Ata\"i, J. Djuvsland, A. Dmytriiev, K. Egberts, K. Egg, S. Einecke, J. -P. Ernenwein, C. Esca\~n, K. Feijen, M. Filipovic, G. Fontaine, S. Funk, S. Gabici, J. F. Glicenstein, P. Goswami, G. Grolleron, B. He{\ss}, J. A. Hinton, M. Holler, M. Jamrozy, F. Jankowsky, I. Jung-Richardt, E. Kasai, K. Katarzy\'n, H. Katjaita, D. Kerszberg, R. Khatoon, B. Kh\'elifi, W. Klu\'z, Nu. Komin, R. Konno, K. Kosack, D. Kostunin, G. Kukec Mezek, R. G. Lang, A. Lemi\`ere, M. Lemoine-Goumard, J. -P. Lenain, A. Luashvili, J. Mackey, V. Marandon, G. Mart\'i-Devesa, R. Marx, M. Mayer, A. Mehta, A. Mitchell, R. Moderski, M. O. Moghadam, L. Mohrmann, E. Moulin, M. de Naurois, J. Niemiec, E. de Ona Wilhelmi, S. Panny, M. Panter, R. D. Parsons, U. Pensec, P. Pichard, G. P\"uhlhofer, M. Punch, A. Quirrenbach, M. Regeard, O. Reimer, H. Ren, F. Rieger, G. Rowell, B. Rudak, K. Sabri, V. Sahakian, H. Salzmann, M. Sasaki, J. Sch\"afer, F. Sch\"ussler, H. M. Schutte, M. Senniappan, J. N. S. Shapopi, A. Sharma, H. Sol, S. Spencer, {\L}., R. Steenkamp, S. Steinmassl, C. Steppa, T. Takahashi, T. Tanaka, A. M. Taylor, M. Tsirou, C. van Eldik, M. Vecchi, C. Venter, J. Vink, T. Wach, S. J. Wagner, A. Wierzcholska, M. Zacharias, A. A. Zdziarski, A. Zech, N. \.Zywucka, S. Abe, J. Abhir, A. Abhishek, A. Aguasca-Cabot, I. Agudo, T. Aniello, S. Ansoldi, L. A. Antonelli, A. Arbet Engels, C. Arcaro, M. Artero, K. Asano, A. Babi\'c, C. Bakshi, U. Barres de Almeida, J. A. Barrio, L. Barrios-Jim\'enez, I. Batkovi\'c, J. Baxter, J. Becerra Gonz\'alez, W. Bednarek, E. Bernardini, J. Bernete, A. Berti, J. Besenrieder, C. Bigongiari, A. Biland, O. Blanch, H. B\"okenkamp, G. Bonnoli, \v{Z}, E. Bronzini, I. Burelli, A. Campoy-Ordaz, A. Carosi, R. Carosi, M. Carretero-Castrillo, A. J. Castro-Tirado, D. Cerasole, G. Ceribella, Y. Chai, A. Chilingarian, A. Cifuentes, J. L. Contreras, J. Cortina, S. Covino, G. D'Amico, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, C. Delgado Mendez, F. Di Pierro, R. Di Tria, L. Di Venere, A. Dinesh, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, L. Eisenberger, D. Elsaesser, J. Escudero, L. Fari\~na, A. Fattorini, L. Foffano, L. Font, S. Fr\"ose, Y. Fukazawa, S. Gasparyan, M. Gaug, J. G. Giesbrecht Paiva, N. Giglietto, F. Giordano, P. Gliwny, N. Godinovi\'c, T. Gradetzke, R. Grau, D. Green, J. G. Green, P. G\"unther, D. Hadasch, A. Hahn, T. Hassan, L. Heckmann, D. Hrupec, R. Imazawa, D. Israyelyan, I. Jim\'enez Mart\'inez, J. Jim\'enez Quiles, J. Jormanainen, S. Kankkunen, T. Kayanoki, D. Kerszberg, J. Konrad, P. M. Kouch, H. Kubo, J. Kushida, M. L\'ainez, A. Lamastra, E. Lindfors, S. Lombardi, F. Longo, R. L\'opez-Coto, M. L\'opez-Moya, A. L\'opez-Oramas, S. Loporchio, L. Luli\'c, E. Lyard, P. Majumdar, M. Makariev, M. Mallamaci, G. Maneva, M. Manganaro, S. Mangano, S. Marchesi, M. Mariotti, M. Mart\'inez, P. Maru\v{s}, A. Mas-Aguilar, D. Mazin, S. Menchiari, J. M\'endez Gallego, D. Miceli, J. M. Miranda, R. Mirzoyan, M. Molero Gonz\'alez, E. Molina, H. A. Mondal, A. Moralejo, T. Nakamori, C. Nanci, V. Neustroev, M. Nievas Rosillo, C. Nigro, L. Nikoli\'c, K. Nilsson, K. Nishijima, K. Noda, S. Nozaki, A. Okumura, J. Otero-Santos, S. Paiano, D. Paneque, J. M. Paredes, M. Peresano, M. Persic, M. Pihet, F. Podobnik, P. G. Prada Moroni, E. Prandini, M. Rib\'o, J. Rico, T. Saito, S. Sakurai, K. Satalecka, F. G. Saturni, K. Schmitz, F. Schmuckermaier, J. L. Schubert, A. Sciaccaluga, G. Silvestri, J. Sitarek, V. Sliusar, D. Sobczynska, A. Stamerra, J. Stri\v{s}, D. Strom, M. Strzys, Y. Suda, H. Tajima, M. Takahashi, R. Takeishi, P. Temnikov, K. Terauchi, T. Terzi\'c, A. Tutone, S. Ubach, J. van Scherpenberg, M. Vazquez Acosta, S. Ventura, G. Verna, I. Viale, A. Vigliano, C. F. Vigorito, E. Visentin, V. Vitale, I. Vovk, R. Walter, F. Wersig, M. Will, T. Yamamoto, P. K. H. Yeung, S. Yoo, A. Acharyya, A. Archer, P. Bangale, J. T. Bartkoske, W. Benbow, J. H. Buckley, Y. Chen, J. L. Christiansen, A. J. Chromey, M. Errando, S. Feldman, Q. Feng, S. Filbert, L. Fortson, A. Furniss, W. Hanlon, O. Hervet, C. E. Hinrichs, J. Holder, Z. Hughes, T. B. Humensky, W. Jin, M. N. Johnson, P. Kaaret, M. Kertzman, M. Kherlakian, D. Kieda, T. K. Kleiner, N. Korzoun, M. J. Lang, M. Lundy, G. Maier, M. J. Millard, J. Millis, P. Moriarty, R. Mukherjee, W. Ning, R. A. Ong, A. Pandey, M. Pohl, J. Quinn, P. L. Rabinowitz, K. Ragan, P. T. Reynolds, D. Ribeiro, E. Roache, I. Sadeh, A. C. Sadun, L. Saha, M. Santander, G. H. Sembroski, R. Shang, D. Tak, A. K. Talluri, J. V. Tucci, J. Valverde, V. V. Vassiliev, D. A. Williams, S. L. Wong, S. Buson, R. Abbasi, M. Ackermann, J. Adams, S. K. Agarwalla, J. A. Aguilar, M. Ahlers, J. M. Alameddine, S. Ali, N. M. Amin, K. Andeen, C. Arg\"u, Y. Ashida, S. Athanasiadou, S. N. Axani, R. Babu, X. Bai, J. Baines-Holmes, A. Balagopal V., S. W. Barwick, S. Bash, V. Basu, R. Bay, J. J. Beatty, J. Becker Tjus, P. Behrens, J. Beise, C. Bellenghi, B. Benkel, S. BenZvi, D. Berley, E. Bernardini, D. Z. Besson, E. Blaufuss, L. Bloom, S. Blot, I. Bodo, F. Bontempo, J. Y. Book Motzkin, C. Boscolo Meneguolo, S. B\"o, O. Botner, J. B\"o, J. Braun, B. Brinson, Z. Brisson-Tsavoussis, R. T. Burley, D. Butterfield, M. A. Campana, K. Carloni, J. Carpio, S. Chattopadhyay, N. Chau, Z. Chen, D. Chirkin, S. Choi, B. A. Clark, A. Coleman, P. Coleman, G. H. Collin, D. A. Coloma Borja, A. Connolly, J. M. Conrad, D. F. Cowen, C. De Clercq, J. J. DeLaunay, D. Delgado, T. Delmeulle, S. Deng, P. Desiati, K. D. de Vries, G. de Wasseige, T. DeYoung, J. C. D\'i, S. DiKerby, T. Ding, M. Dittmer, A. Domi, L. Draper, L. Dueser, D. Durnford, K. Dutta, M. A. DuVernois, T. Ehrhardt, L. Eidenschink, A. Eimer, P. Eller, E. Ellinger, D. Els\"a, R. Engel, H. Erpenbeck, W. Esmail, S. Eulig, J. Evans, P. A. Evenson, K. L. Fan, K. Fang, K. Farrag, A. R. Fazely, A. Fedynitch, N. Feigl, C. Finley, L. Fischer, D. Fox, A. Franckowiak, S. Fukami, P. F\"u, J. Gallagher, E. Ganster, A. Garcia, M. Garcia, G. Garg, E. Genton, L. Gerhardt, A. Ghadimi, C. Glaser, T. Gl\"u, J. G. Gonzalez, S. Goswami, A. Granados, D. Grant, S. J. Gray, S. Griffin, S. Griswold, K. M. Groth, D. Guevel, C. G\"u, P. Gutjahr, C. Ha, C. Haack, A. Hallgren, L. Halve, F. Halzen, L. Hamacher, M. Ha Minh, M. Handt, K. Hanson, J. Hardin, A. A. Harnisch, P. Hatch, A. Haungs, J. H\"a, K. Helbing, J. Hellrung, B. Henke, L. Hennig, F. Henningsen, L. Heuermann, R. Hewett, N. Heyer, S. Hickford, A. Hidvegi, C. Hill, G. C. Hill, R. Hmaid, K. D. Hoffman, D. Hooper, S. Hori, K. Hoshina, M. Hostert, W. Hou, M. Hrywniak, T. Huber, K. Hultqvist, K. Hymon, A. Ishihara, W. Iwakiri, M. Jacquart, S. Jain, O. Janik, M. Jansson, M. Jeong, M. Jin, N. Kamp, D. Kang, W. Kang, X. Kang, A. Kappes, L. Kardum, T. Karg, M. Karl, A. Karle, A. Katil, M. Kauer, J. L. Kelley, M. Khanal, A. Khatee Zathul, A. Kheirandish, H. Kimku, J. Kiryluk, C. Klein, S. R. Klein, Y. Kobayashi, A. Kochocki, R. Koirala, H. Kolanoski, T. Kontrimas, L. K\"o, C. Kopper, D. J. Koskinen, P. Koundal, M. Kowalski, T. Kozynets, A. Kravka, N. Krieger, J. Krishnamoorthi, T. Krishnan, K. Kruiswijk, E. Krupczak, A. Kumar, E. Kun, N. Kurahashi, N. Lad, C. Lagunas Gualda, L. Lallement Arnaud, M. Lamoureux, M. J. Larson, F. Lauber, J. P. Lazar, K. Leonard DeHolton, A. Leszczy\'n, J. Liao, C. Lin, Y. T. Liu, M. Liubarska, C. Love, L. Lu, F. Lucarelli, W. Luszczak, Y. Lyu, M. Macdonald, J. Madsen, E. Magnus, Y. Makino, E. Manao, S. Mancina, A. Mand, I. C. Mari\c{s}, S. Marka, Z. Marka, L. Marten, I. Martinez-Soler, R. Maruyama, J. Mauro, F. Mayhew, F. McNally, J. V. Mead, K. Meagher, S. Mechbal, A. Medina, M. Meier, Y. Merckx, L. Merten, J. Mitchell, L. Molchany, S. Mondal, T. Montaruli, R. W. Moore, Y. Morii, A. Mosbrugger, M. Moulai, D. Mousadi, E. Moyaux, T. Mukherjee, R. Naab, M. Nakos, U. Naumann, J. Necker, L. Neste, M. Neumann, H. Niederhausen, M. U. Nisa, K. Noda, A. Noell, A. Novikov, A. Obertacke, V. O'Dell, A. Olivas, R. Orsoe, J. Osborn, E. O'Sullivan, V. Palusova, H. Pandya, A. Parenti, N. Park, V. Parrish, E. N. Paudel, L. Paul, C. P\'e, T. Pernice, T. C. Petersen, J. Peterson, M. Plum, A. Pont\'e, V. Poojyam, Y. Popovych, M. Prado Rodriguez, B. Pries, R. Procter-Murphy, G. T. Przybylski, L. Pyras, C. Raab, J. Rack-Helleis, N. Rad, M. Ravn, K. Rawlins, Z. Rechav, A. Rehman, I. Reistroffer, E. Resconi, S. Reusch, C. D. Rho, W. Rhode, L. Ricca, B. Riedel, A. Rifaie, E. J. Roberts, M. Rongen, A. Rosted, C. Rott, T. Ruhe, L. Ruohan, D. Ryckbosch, J. Saffer, D. Salazar-Gallegos, P. Sampathkumar, A. Sandrock, G. Sanger-Johnson, M. Santander, S. Sarkar, J. Savelberg, M. Scarnera, P. Schaile, M. Schaufel, H. Schieler, S. Schindler, L. Schlickmann, B. Schl\"u, F. Schl\"u, N. Schmeisser, T. Schmidt, F. G. Schr\"o, L. Schumacher, S. Schwirn, S. Sclafani, D. Seckel, L. Seen, M. Seikh, S. Seunarine, P. A. Sevle Myhr, R. Shah, S. Shefali, N. Shimizu, B. Skrzypek, R. Snihur, J. Soedingrekso, A. S{\o}, D. Soldin, P. Soldin, G. Sommani, C. Spannfellner, G. M. Spiczak, C. Spiering, J. Stachurska, M. Stamatikos, T. Stanev, T. Stezelberger, T. St\"u, T. Stuttard, G. W. Sullivan, I. Taboada, S. Ter-Antonyan, A. Terliuk, A. Thakuri, M. Thiesmeyer, W. G. Thompson, J. Thwaites, S. Tilav, K. Tollefson, S. Toscano, D. Tosi, A. Trettin, A. K. Upadhyay, K. Upshaw, A. Vaidyanathan, N. Valtonen-Mattila, J. Valverde, J. Vandenbroucke, T. Van Eeden, N. van Eijndhoven, L. Van Rootselaar, J. van Santen, J. Vara, F. Varsi, M. Venugopal, M. Vereecken, S. Vergara Carrasco, S. Verpoest, D. Veske, A. Vijai, J. Villarreal, C. Walck, A. Wang, E. H. S. Warrick, C. Weaver, P. Weigel, A. Weindl, J. Weldert, A. Y. Wen, C. Wendt, J. Werthebach, M. Weyrauch, N. Whitehorn, C. H. Wiebusch, D. R. Williams, L. Witthaus, M. Wolf, G. Wrede, X. W. Xu, J. P. Yanez, Y. Yao, E. Yildizci, S. Yoshida, R. Young, F. Yu, S. Yu, T. Yuan, A. Zander Jurowitzki, A. Zegarelli, S. Zhang, Z. Zhang, P. Zhelnin, P. Zilberman, F. D'Ammando - A vision for ground-based astronomy beyond the 2030s: How to build ESO's next big telescope sustainably - https://arxiv.org/abs/2512.10902 - arXiv:2512.10902v1 Announce Type: new -Abstract: Astronomy is the study of the Universe and all the objects that it comprises. Our attention is therefore usually focused beyond Earth, home to the only form of life known today. However, how can we continue to explore the secrets of the Universe, if we stand by and watch our only home burn? We know that there is no Planet B. It is therefore urgent that, as astronomers, we collectively work to protect the Earth, allowing future generations the opportunity to continue to uncover the secrets of the cosmos. As astronomical facilities account for the majority of our community's carbon footprint, we propose guidelines that we hold crucial for the European Southern Observatory (ESO) to consider in the context of the Expanding Horizons programme as it plans a next-generation, transformational facility. - oai:arXiv.org:2512.10902v1 - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + A Tidal Disruption Event from an Intermediate-mass Black Hole Revealed by Comprehensive Multi-wavelength Observations + https://arxiv.org/abs/2512.16568 + arXiv:2512.16568v1 Announce Type: new +Abstract: Tidal disruption events (TDEs) occur when a star crosses the tidal radius of a black hole (BH) and is ripped apart, providing a novel and powerful way to probe dormant BHs over a wide mass range. In this study, we present our late-time observations and comprehensive multi-wavelength analyses of an extraordinary TDE at the center of a dwarf galaxy, which exhibited successive flares in the optical, X-ray, and radio bands. Notably, we discovered an unexpected high-state X-ray plateau phase following the peak until the present time. Along with its reported prolonged rise lasting at least 550 days, these unique characteristics are consistent with the scenario of a TDE caused by an intermediate-mass black hole (IMBH) with a mass of approximately $(1-6) \times 10^5$ solar masses. Furthermore, scaling relations derived from the host-galaxy properties indicated a similar BH mass in concert. This discovery highlights the invaluable role of TDEs in the search for elusive IMBHs. + oai:arXiv.org:2512.16568v1 + astro-ph.HE + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Laurane Fr\'eour, Mathilde Bouvier, Tony Mroczkowski, Callie Clontz, Fatemeh Zahra Majidi, Vasundhara Shaw, Olivier Absil, Anna Cabr\'e, Olivier Lai, Dylan Magill, Jake D. Turner + Jialai Wang, Mengqiu Huang, Yongquan Xue, Ning Jiang, Shifeng Huang, Yibo Wang, Jiazheng Zhu, Shifu Zhu, Lixin Dai, Chichuan Jin, Bin Luo, Xinwen Shu, Mouyuan Sun, Tinggui Wang, Fan Zou - A Stellar Magnesium to Silicon ratio in the atmosphere of an exoplanet - https://arxiv.org/abs/2512.10904 - arXiv:2512.10904v1 Announce Type: new -Abstract: The elemental compositions of exoplanets encode information about their formation environments and internal structures. While volatile ratios such as carbon-to-oxygen (C/O) are used to trace formation location, the rock-forming elements - magnesium (Mg), silicon (Si), and iron (Fe) - govern interior mineralogy and are commonly assumed to reflect the host star's abundances. Yet this assumption remains largely untested. Ultra-hot Jupiters, gas-giant exoplanets with dayside temperatures above 3000 K, provide rare access to refractory elements that remain gaseous. Here we present high-resolution thermal emission spectroscopy of the exoplanet WASP-189b (Teq = 3354^{+27}_{-34} K) obtained with the Immersion Grating Infrared Spectrometer (IGRINS) on Gemini South. We detect neutral iron (Fe I), magnesium (Mg I), silicon (Si I), water (H_2O), carbon monoxide (CO), and hydroxyl (OH) at signal-to-noise ratios exceeding 4, and retrieve their elemental abundances. We show that the Mg/Si, Fe/Mg, and Si/Fe ratios are consistent with stellar values, while the refractory-to-volatile ratio is enhanced by roughly a factor of ~2. These findings demonstrate that giant-planet atmospheres can preserve stellar-like rock-forming ratios, providing an empirical validation of the stellar-proxy assumption that underpins planetary composition and formation models across exoplanet systems. - oai:arXiv.org:2512.10904v1 + Probing thermal gradients of habitable-zone rocky planets using direct imaging as an anti-indicator of a global surface ocean + https://arxiv.org/abs/2512.16575 + arXiv:2512.16575v1 Announce Type: new +Abstract: Future direct-imaging missions, such as the Large Interferometer for Exoplanets (LIFE), aim to observe thermal emission from potentially habitable planets to characterize their surface environments and search for signs of life. Previous studies of directly imaged Earth-like planets have mainly examined the signatures of atmospheric composition, often using one-dimensional models, while the effect of horizontal temperature gradients has received limited attention. Because a pronounced horizontal temperature gradient may signal the absence of a global ocean, we investigate its detectability through thermal-emission direct imaging. Adopting Teegarden's Star b (zero-albedo equilibrium temperature $\sim 280$~K) as a benchmark, we compute three-dimensional atmospheric structures with and without a global ocean using the ROCKE-3D general circulation model and simulate geometry-dependent thermal emission spectra. We show that the temperature gradients that disfavor a global-ocean scenario manifest in both orbital phase variation and spectral shape of the snapshot spectra. The phase variation is more readily detectable: one-day integrations with LIFE at two orbital phases would reveal flux variations in no-ocean cases with 1-10~bar atmospheres, depending on background atmospheric composition. Shapshot spectra provide complementary diagnostics of global temperature contrast, the running brightness temperature of the continuum and detailed absorption band shapes, but require integration a few times longer. These three-dimensional effects, if neglected, can bias interpretations based on one-dimensional models. We also assess their detectability for other nearby exoplanets. Our results highlight the need to incorporate three-dimensional atmospheric structures when characterizing rocky exoplanets, both to constrain surface conditions and to avoid misinterpretation of spectral data. + oai:arXiv.org:2512.16575v1 astro-ph.EP - astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Jorge A. Sanchez, Peter C. B. Smith, Krishna Kanumalla, Luis Welbanks, Michael R. Line, Stefan Pelletier, Steven Desch, Patrick Young, Jennifer Patience, Jacob Bean, Matteo Brogi, Dan Jaffe, Gregory N. Mace, Megan Weiner Mansfield, Vatsal Panwar, Vivien Parmentier, Lorenzo Pino, Arjun Baliga Savel, Lennart van Sluijs, Joost P. Wardenier + Yuka Fujii, Daniel Angerhausen, Taro Matsuo, Eric T. Wolf + + + JWST MIRI color classification of mid-infrared selected galaxies: MIRI color classification toward cosmic noon + https://arxiv.org/abs/2512.16589 + arXiv:2512.16589v1 Announce Type: new +Abstract: We investigated the James Webb Space Telescope photometric color classification of mid-infrared (MIR) selected galaxies at high redshifts, toward cosmic noon. The aim of the present work is to obtain a z-dependent mid-infrared (MIR) photometric galaxy classification tool based on broad spectral emission and absorption lines using the JWST Mid-Infrared Instrument (MIRI) and its broadband filters. We used the largest Spitzer MIR spectral database to obtain synthetic photometry in the JWST/MIRI filters. We formed MIRI filter combinations to trace the strong polycyclic aromatic hydrocarbon (PAH) emission features and the 9.7 micron silicate feature in seven redshift windows from z = 0.25-2.10. Results. We present z-dependent MIRI color-color plots that separate active galactic nuclei (AGN), star-forming galaxies (SFGs), and silicate absorption-dominated galaxies up to z$\sim$2. We applied the photometric MIR colors to the largest ($\sim$34 arcmin square) MIRI survey called the Systematic Mid-infrared Instrument Legacy Extragalactic Survey (SMILES), to identify AGN, SFGs, and Si-absorption dominated galaxies out to substantial redshifts. Our JWST/MIRI SFGs sample includes galaxies with total IR luminosities of $10^{9.2} \sim 10^{11.9} L_{\odot}$ at 0.9 $\leq$z < 1.57. The majority of them are consistent with the z$\sim$1 main sequence. We also identified the first examples of z$\sim$1 galaxies with deep silicate absorption. + oai:arXiv.org:2512.16589v1 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1051/0004-6361/202554884 + Astronomy & Astrophysics, 2025, Volume 704, id.A71 + Ece Kilerci, Tomotsugu Goto, Matthew A. Malkan, Seong Jin Kim, Chih-Teng Ling, Cossas C. -K Wu, Tetsuya Hashimoto, Simon C. -C. Ho, Amos Y. -A. Chen, Ersin Gogus - Shedding Light on Large Space-Based Telescopes: Modeling Stray Light due to Primary Mirror Damage from Micrometeoroid Impacts - https://arxiv.org/abs/2512.10915 - arXiv:2512.10915v1 Announce Type: new -Abstract: A large space-based telescope aimed at detecting and characterizing the atmospheres of Earth-like planets orbiting Sun-like stars will require unprecedented contrast and stability. However, damage to the primary mirror due to micrometeoroid impacts will provide a stochastic, time-dependent source of stray light in the coronagraph's field of view that could significantly lengthen exposure times and reduce the expected science yield. To better quantify the impact of stray light and inform the Habitable Worlds Observatory mission design process, we present estimates of stray light in different micrometeoroid damage scenarios for a broad range of targets, and use that to find the expected decrease in science yield (i.e., the expected number of detected exoEarth candidates). We find that stray light due to micrometeoroid damage may significantly reduce yield, by 30% -- 60% in some cases, but significant uncertainties remain due to the unknown maximum expected impactor energy, and the relationship between impact energy and expected crater size. Micrometeoroid damage therefore needs further exploration, as it has the potential to reduce scientific yield, and in turn drive the development of mitigation strategies, selection of telescope designs, and selection of observing priorities in the future. - oai:arXiv.org:2512.10915v1 + An effective $\boldsymbol{\Lambda}$-Szekeres modelling of the local Universe with Cosmicflows-4 + https://arxiv.org/abs/2512.16591 + arXiv:2512.16591v1 Announce Type: new +Abstract: We develop an effective description of the local cosmic environment, namely, for redshift $z \lesssim 0.1$, to quantify the bias induced by local structure on cosmological observables. Our approach models the metric of the nearby Universe as a superposition of multi-structured $\Lambda$-Szekeres patches, calibrated against the HAMLET peculiar velocity and density field reconstructions of Cosmicflows-4. From this framework we compute the fully inhomogeneous and anisotropic quasilocal expansion field predicted by our model, and use it to assess the impact of local structure on estimates of $H_0$. For this purpose we analyse low-redshift Type Ia supernovae from the Pantheon+ catalogue. We find that accounting for the local structure increases the Hubble tension, yielding a shift in the best-fit value of the Hubble constant of order $\Delta H_0 \approx 0.5\ \mathrm{km\,s^{-1}Mpc^{-1}}$. + oai:arXiv.org:2512.16591v1 + astro-ph.CO + gr-qc + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Marco Galoppo, Leonardo Giani, Morag Hills, Aur\'elien Valade + + + Closed Form Expressions for the Potentials and Accelerations of Generalized Ring Models + https://arxiv.org/abs/2512.16618 + arXiv:2512.16618v1 Announce Type: new +Abstract: We present several closed-form expressions of useful mass distributions. These include the potentials and accelerations of circular rings and arcs, the potentials of uniform density rings and arcs at arbitrary eccentricities, and the potentials and accelerations of rings and arcs when the mass is time-averaged over a Kepler orbit. We show that these expressions can be expressed, often simply, in terms of elliptic functions of complex arguments. We show that in a few limiting cases, the expressions are entirely real. We expect that these expressions will allow for more rapid modeling in many areas of celestial mechanics. + oai:arXiv.org:2512.16618v1 astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Zachary Murray + + + Observing spatial and temporal variations in the atmospheric chemistry of rocky exoplanets: prospects for mid-infrared spectroscopy + https://arxiv.org/abs/2512.16619 + arXiv:2512.16619v1 Announce Type: new +Abstract: Future telescopes such as the Large Interferometer For Exoplanets (LIFE) will enable mid-infrared characterisation of the atmospheres of nearby rocky exoplanets. Whilst 4D spatial and temporal variations of Earth as an exoplanet are below spectroscopic detection limits, such variability is planet-specific. We investigate LIFE's ability to detect 4D variability in the atmospheres of tidally locked exoplanets. We create daily synthetic LIFE observations of Proxima Centauri b in a 1:1 and an eccentric 3:2 spin-orbit resonance (SOR), using LIFEsim on spectra from daily 3D climate-chemistry model output of an aquaplanet with Earth-like composition. Hemispheric distributions of temperature, clouds, and chemical species determine spectral signatures and variability with orbital phase angle. Such variability dictates the extent to which parameters can be reliably inferred from snapshot spectra at arbitrary viewing geometries. In the 1:1 SOR, MIR spectra vary significantly with viewing geometry and indirectly probe atmospheric circulation. Nightside temperature inversions generate O3, CO2, and H2O emission features, though these lie below LIFE's detection threshold, and instead O3 features disappear at certain phase angles. In contrast, the 3:2 SOR yields a more homogeneous atmosphere with weaker phase variability but enhanced bolometric flux due to eccentric heating. Phase-resolved LIFE observations confidently distinguish between the SORs and capture seasonal O3 variability for golden targets like Proxima Centauri b. In case of abiotic O2/O3 build-up, the O3 variability presents a potential false positive scenario. Hence, LIFE can disentangle different spin-orbit states and resolve 4D atmospheric variability, enabling daily characterisation of the 4D physical and chemical state of nearby terrestrial worlds. Importantly, this characterisation requires phase-resolved rather than snapshot spectra. + oai:arXiv.org:2512.16619v1 + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Marrick Braam, Daniel Angerhausen + + + The high-redshift radio galaxy 3C 294 at low frequencies: radio detection of the X-ray Ghost + https://arxiv.org/abs/2512.16621 + arXiv:2512.16621v1 Announce Type: new +Abstract: We report on the very first radio detection associated with the peculiar hourglass-morphology X-rays surrounding 3C 294 at z=1.8. Using International Low Frequency Array (LOFAR) data at 144 MHz and Chandra data at 0.3-6 keV, we find that the co-spatial diffuse radio and X-ray emission is well described by synchrotron and inverse-Compton processes by the same electron population. Through modelling of this rare low-energy plasma, we find that the most defining property of the electrons up-scattering CMB photons at this redshift is very low electron Lorentz factors ($\gamma_{\text{max}}\ll 10^{4}$ and $\gamma_{\text{break}}\lesssim 10^{3}$) in the lobe: deep low frequency (<150 MHz) observations are critical to the detection of radio lobes at high redshift. The physical conditions imply a total energy in the diffuse emission significantly greater than that implied by the temperature of the protocluster gas: 3C 294 is one of the most powerful known radio-loud systems in a dense protocluster environment. Through resolved spectral analysis of archival radio data up to 15 GHz, we find evidence that the inner hotspots are due to restarted activity, while the outer hotspots remain energetic, suggesting a rapid duty cycle while the jet precesses. This allowed the low-energy aged plasma driving the X-rays to remain spatially distinct from the high-energy plasma. Together, our results promise a revelation of AGN-related radio emission at high redshift using future low-frequency arrays such as SKA-LOW. + oai:arXiv.org:2512.16621v1 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Vijay H. Mahatma, Andrew C. Fabian, Leah K. Morabito + + + Cygnus X-3: A variable petaelectronvolt gamma-ray source + https://arxiv.org/abs/2512.16638 + arXiv:2512.16638v1 Announce Type: new +Abstract: We report the discovery of variable $\gamma$-rays up to petaelectronvolt from Cygnus X-3, an iconic X-ray binary.The $\gamma$-ray signal was detected with a statistical significance of approximately 10 $\sigma$ by the Large High Altitude Air Shower Observatory (LHAASO).Its intrinsic spectral energy distribution (SED), extending from 0.06 to 3.7 PeV, shows a pronounced rise toward 1 PeV after accounting for absorption by the cosmic microwave background radiation.The detected month-scale variability,together with a 3.2$\sigma$ evidence for orbital modulation, suggests that the PeV $\gamma$-rays originate within, or in close proximity to, the binary system itself.The observed energy spectrum and temporal modulation can be naturally explained by $\gamma$-ray production through photomeson processes in the innermost region of the relativistic jet, where protons need to be accelerated to tens of PeV energies. + oai:arXiv.org:2512.16638v1 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + LHAASO Collaboration + + + The Preliminary Mauve Science Programme: Science themes identified for the first year of operations + https://arxiv.org/abs/2512.16675 + arXiv:2512.16675v1 Announce Type: new +Abstract: Mauve is a low-cost small satellite developed and operated by Blue Skies Space Ltd. The payload features a 13 cm telescope connected with a fibre that feeds into a UV-Vis spectrometer. The detector covers the 200-700 nm range in a single shot, obtaining low resolution spectra at R~20-65. Mauve has launched on 28th November 2025, reaching a 510 km Low-Earth Sun-synchronous orbit. The satellite will enable UV and visible observations of a variety of stellar objects in our Galaxy, filling the gaps in the ultraviolet space-based data. The researchers that have already joined the mission have defined the science themes, observational strategy and targets that Mauve will observe in the first year of operations. To date, 10 science themes have been developed by the Mauve science collaboration for year 1, with observational strategies that include both long duration monitoring and short cadence snapshots. Here, we describe these themes and the science that Mauve will undertake in its first year of operations. + oai:arXiv.org:2512.16675v1 + astro-ph.SR astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Mauve Science Collaboration, Marcel Agueros, Don Dixon, Chuanfei Dong, Girish M. Duvvuri, Patrick Flanagan, Christopher Johns-Krull, Hongpeng Lu, Hiroyuki Maehara, Kosuke Namekata, Alejandro Nunez, Elena Pancino, Sharmila Rani, Anusha Ravikumar, T. A. A. Sigut, Keivan Stassun, Jamie Stewart, Kriszti\'an Vida, Emma Whelan, Benjamin Wilcock, Sharafina Razin, Arianna Saba, Giovanna Tinetti, Marcell Tessenyi, Jonathan Tennyson + + + Einstein Probe Discovery of an X-ray Flare from K-type Star PM J23221-0301 + https://arxiv.org/abs/2512.16679 + arXiv:2512.16679v1 Announce Type: new +Abstract: Stellar flares are an intense stellar activity that can significantly impact the atmospheric composition of the surrounding planets and even the possible existence of life. During such events, the radiative energy of the star is primarily concentrated in the optical and X-ray bands, with the X-ray flux potentially increasing by tens or even hundreds of times. Einstein Probe (EP) detected a new X-ray transient EP J2322.1-0301 on 27 September 2024. Its spatial localization shows a high positional coincidence with the nearby high proper motion K-type star PM J23221-0301. Follow-up X-ray observations confirmed the flux enhancement of the source, while optical spectroscopic monitoring revealed time-variable features, particularly the disappearance of the H-alpha emission line. This X-ray flare is consistent with a characteristic fast-rise-exponential-decay (FRED) light curve, with a rise timescale of 1.4 ks, a decay timescale of 5.7 ks, and a total duration of about 7.1 ks. The peak luminosity in the 0.5-4.0 keV energy band reached about 1.3 x 10^31 erg s^-1, with a total energy release of about 9.1 x 10^34 erg, consistent with the empirical energy correlations observed in magnetic-reconnection-driven stellar flares, as inferred from the multitemperature plasma structure and H-alpha-X-ray energy correlation. This discovery underscores EP's capability in understanding stellar magnetic activity via observing stellar transients. + oai:arXiv.org:2512.16679v1 + astro-ph.HE + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Guoying Zhao, WeiKang Zheng, Rong-Feng Shen, Qingcang Shui, Dongyue Li, Chang Zhou, Tianci Zheng, Weimin Yuan, Chong Ge, Junfeng Wang, Alexei V. Filippenko, Thomas G. Brink, Jordan Forman, Mayra Gutierrez, Isabelle Jones, Ravjit Kaur, Naunet Leonhardes-Barboza, Petra Mengistu, Avi Patel, Andrew Skemer, Anavi Uppal, Nicole Wolff, Michele N. Woodland + + + Comparison of General Circulation Models of the Venus upper atmosphere + https://arxiv.org/abs/2512.16693 + arXiv:2512.16693v1 Announce Type: new +Abstract: In the context of future Venusian missions, it is crucial to improve our understanding of Venus upper atmosphere through 3D modeling, notably for spacecraft orbit computation. This study compares three General Circulation Models (GCMs) of the Venusian atmosphere up to the exosphere: the Venus Planetary Climate Model (Venus PCM), the Venus Thermospheric Global Model (VTGCM) and the Tohoku University GCM (TUGCM), focusing on their nominal simulations (e.g. composition, thermal structure and heating/cooling rates). Similarities and discrepancies among them are discussed in this paper, together with data-models comparison. The nominal simulations analyzed in this study fail to accurately reproduce the daytime observations of Pioneer Venus, notably overestimating the exospheric temperature. This is linked to an underestimation of the atomic oxygen (O) abundance in the three GCMs, and suggests the need of additional O production in the thermosphere. The selection of solar spectrum is also the main reason for the discrepancies between the models in terms of temperature dependence on solar activity. A list of recommendations is proposed aiming at improving the modeling of Venus' upper atmosphere, among them: 1. Standardize the EUV-UV solar spectrum input. 2. Update the near-infrared heating scheme with Venus Express-Era data. 3. Reassess Radiative cooling schemes. 4. Investigate the underestimated atomic Oxygen abundance. + oai:arXiv.org:2512.16693v1 + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Megan T. Gialluca, Jonathan W. Arenberg, Chris Stark, Blake Shepherd, Victoria S. Meadows, Aki Roberge, Tyler D. Robinson, Robert Podgurski + 10.1016/j.icarus.2025.116901 + Icarus, March 2026, Volume 447 + Antoine Martinez, Hiroki Karyu, Amanda Brecht, Gabriella Gilli, Sebastien Lebonnois, Takeshi Kuroda, Aurelien Stolzenbach, Francisco Gonzalez Galindo, Stephen Bougher, Hitoshi Fujiwara - Detection prospects for heavy WIMP dark matter near supermassive black holes, particularly in M31 - https://arxiv.org/abs/2512.10923 - arXiv:2512.10923v1 Announce Type: new -Abstract: This work analyzes the detection prospects for weakly interacting massive particles (WIMPs) in dark matter (DM) density spikes around nearby supermassive black holes (SMBHs) by observations in very high energy gamma-ray band. Such spikes are unique targets, which provide a possibility to discover the basic thermal s-wave annihilating WIMP with any mass up to the theoretical unitarity limit ~ 100 TeV. All relevant SMBHs were checked, and only MW* and M31* were identified as worthwhile objects. Cherenkov Telescope Array (CTA) sensitivity to heavy WIMPs in M31* was estimated. It was obtained that CTA will be able to probe a major part of TeV-scale WIMP parameter space in case of optimistic spike density configuration in M31*. In certain scenarios, M31* may yield even stronger constraints than MW*. Relevant systematic uncertainties were explored. - oai:arXiv.org:2512.10923v1 + Discovery of two new millisecond pulsars towards the Galactic bulge + https://arxiv.org/abs/2512.16699 + arXiv:2512.16699v1 Announce Type: new +Abstract: The mysterious Galactic Center Excess of gamma rays could be explained by a large population of millisecond pulsars hiding in the Galactic bulge, too faint to be detected as individual high-energy point sources by the Fermi Large Area Telescope, as well as too fast and too dispersed to be detected in shallow radio pulsation surveys. Motivated by an innovative candidate selection method, we aim at detecting millisecond pulsars associated with the Galactic Center Excess by carrying deep radio pulsation searches towards promising candidates detected in the inner Galaxy, in X rays by Chandra, and in radio or gamma rays by the Very Large Array or Fermi. We conducted deep radio observation and follow-up campaigns with MeerKAT, the Murriyang and the Green Bank telescopes towards 9 X-ray candidate sources. We here report the detection of two new millisecond pulsars, including a black widow candidate, towards the Galactic bulge: PSRs J1740-2805 and J1740-28. These discoveries double the number of MSPs discovered within the innermost 2 degree from the Galactic center. + oai:arXiv.org:2512.16699v1 astro-ph.HE - astro-ph.CO - hep-ph - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Andrei E. Egorov + J. Berteaud, F. Calore, M. Clavel, S. Dai, J. S. Deneva, S. Hyman, F. K. Schinzel, A. Ridolfi, S. M. Ransom, F. Abbate, C. J. Clark, M. Kramer, T. Thongmeearkom, B. W. Stappers, E. D. Barr, R. P. Breton - Signatures of star formation inside galactic outflows - https://arxiv.org/abs/2512.10924 - arXiv:2512.10924v1 Announce Type: new -Abstract: Observations have suggested that galactic outflows contain substantial amounts of dense and clumpy molecular gas, creating favourable conditions for igniting star formation. Indeed, theoretical models and hydrodynamical simulations have suggested that stars could form within galactic outflows, representing a new mode of star-formation that differs significantly from the typical star formation in star forming discs. In this paper, we examine 12 local galaxies with powerful Active Galactic Nuclei and high star-formation rate using spectroscopic data from the X-shooter spectrograph at the Very Large Telescope. We investigate the excitation mechanism and physical properties of these outflows via spatially resolved diagnostic diagrams (along with tests to rule out contribution by shocks and external photoionisation). Out of the seven galaxies with clearly detected outflows, we find robust evidence for star formation within the outflow of one galaxy (IRAS 20551-4250), with two additional galaxies showing tentative signs (IRAS 13120-5453 and F13229-2934). Therefore, our findings support previous results that star formation inside outflows can be a relatively common phenomenon among these active galaxies and may have played an important role in the formation and evolution of the spheroidal component of galaxies. - oai:arXiv.org:2512.10924v1 + On the Origin of Kinematic Structure in the Young Association Serpens OB2 + https://arxiv.org/abs/2512.16708 + arXiv:2512.16708v1 Announce Type: new +Abstract: The Serpens OB2 association (l ~ 18.5 deg, b ~ 1.9 deg, d = 1950 +/- 30 pc) is a large star-forming complex ~65 pc above the Galactic midplane, with a clumpy, elongated structure extending ~50 pc parallel to the plane. We analyse a sample of probable association members, including OB stars and low-to-intermediate-mass young stellar objects (YSOs) from the SPICY catalogue. While both populations are found throughout the association, the OB stars lie preferentially on the side nearest the Galactic plane, while the YSOs are generally younger and more strongly clustered around molecular-cloud clumps detected in 13CO MWISP data. Using Gaia DR3 proper motions to probe the association's internal kinematics, we find aligned stellar velocities on length scales <2 pc, two-point velocity statistics that show increasing velocity differences and predominantly divergent motions at larger separations, and distinct velocities for star clusters within the association. Finally, the association exhibits gradual, but statistically significant global expansion perpendicular to the Galactic plane, with a spatial gradient of 0.10 +/- 0.02 km/s/pc. The expansion of the H II region Sh 2-54, powered by the association's OB stars, may be accelerating the star-forming cloud away from the plane given the system's geometry, plausibly inducing the vertical stellar velocity gradient. The clumpy stellar distribution, correlated velocities on small scales, and increasingly divergent motions on larger scales are consistent with an initial velocity field inherited from a turbulent molecular cloud modified by stellar feedback. Ser OB2 demonstrates that the multi-scale expansion of an OB association can begin even while star formation is still ongoing throughout the complex. + oai:arXiv.org:2512.16708v1 astro-ph.GA + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Michael A. Kuhn (University of Hertfordshire), Robert A. Benjamin (University of Wisconsin-Whitewater), Simran S. Singh (University of Hertfordshire) + + + Simulation-based inference with neural posterior estimation applied to X-ray spectral fitting - III Deriving exact posteriors with dimension reduction and importance sampling + https://arxiv.org/abs/2512.16709 + arXiv:2512.16709v1 Announce Type: new +Abstract: Simulation-based inference (SBI) with neural posterior estimation (NPE) provides rapid X-ray spectral fitting in both Gaussian and Poisson regimes by learning approximate parameter posteriors from simulations. We investigate auto-encoders for compressing high-resolution X-ray spectra, motivated by newAthena X-ray Integral Field Unit (X-IFU), and use likelihood-based importance sampling to refine NPE outputs. Our auto-encoder maps spectra to a low-dimensional latent space and is trained with a custom loss equal to the Cash statistic (C-stat) between simulated and reconstructed spectra. A neural density estimator is then trained on the latent representations. Both models are trained in multiple rounds: at each round, new simulations are drawn from a truncated proposal concentrated around the observation, improving efficiency as the proposal contracts. After NPE convergence, we apply likelihood-based importance sampling to correct the learned posterior. To assess information retention, we train a diagnostic network that predicts the original spectral parameters from the latent space, and we also train a network to learn the likelihood directly to accelerate importance sampling. On X-IFU-like simulations, the auto-encoder and multi-round NPE outperforms PCA and hand-crafted spectral summaries in accuracy and robustness. After importance sampling, the resulting posteriors are statistically indistinguishable from those obtained with nested sampling. On a standard laptop, the full pipeline (simulation, compression, inference, correction) delivers 10x speedups. We further demonstrate the approach on XRISM/Resolve and on lower-resolution NICER and XMM-Newton EPIC-pn data, confirming applicability across instruments and resolutions. Overall, NPE on compressed spectra paired with likelihood-based importance sampling offers an exact yet efficient alternative for Bayesian X-ray spectral fitting. + oai:arXiv.org:2512.16709v1 astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Didier Barret, Simon Dupourqu\'e + + + Multiwavelength identification of millisecond pulsar candidates in the Galactic bulge + https://arxiv.org/abs/2512.16712 + arXiv:2512.16712v1 Announce Type: new +Abstract: The existence of a population of millisecond pulsars in the Galactic bulge is supported, along with other evidence, by the Fermi GeV excess, an anomalous {\gamma}-ray emission detected almost 15 years ago in the direction of the Galactic center. However, radio surveys searching for pulsations have not yet revealed bulge millisecond pulsars. Identifying promising bulge millisecond pulsar candidates is key to motivating pointed radio pulsation searches. Candidates are often selected among steep-spectrum or polarized radio sources, but multiwavelength information can also be exploited: The aim of this work is to pinpoint strong candidates among the yet unidentified X-ray sources. We investigated the multiwavelength counterparts of sources detected by the Chandra X-ray observatory that have spectral properties expected for millisecond pulsars in the Galactic bulge. We considered that ultraviolet, optical, and strong infrared counterparts indicate that an X-ray source is not a bulge pulsar, while a radio or a faint infrared counterpart makes it a promising candidate. We identify a large population of more than a thousand X-ray sources without optical, ultraviolet, or strong infrared counterparts. Among them, five are seen for the first time in unpublished radio imaging data from the Very Large Array. We provide the list of promising candidates, for most of which follow-up pulsation searches are ongoing. + oai:arXiv.org:2512.16712v1 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + 10.1051/0004-6361/202449473 + Astronomy & Astrophysics, Volume 690, id.A330, 9 pp., October 2024 + J. Berteaud, F. Calore, M. Clavel, J. Marvil, S. Hyman, F. K. Schinzel, M. Kerr + + + Evidence of Possible Spectral Variability in the Patroclus-Menoetius Binary System + https://arxiv.org/abs/2512.16714 + arXiv:2512.16714v1 Announce Type: new +Abstract: We present new visible-wavelength spectroscopic observations of the Patroclus-Menoetius binary system in the Jupiter Trojan population. Motivated by previously published spectra from different instruments that showed evidence of significant longitudinal variability, we obtained two spectra spanning 440-680 nm at near-opposite rotational phases with the Gemini Multi-Object Spectrograph on the Gemini South telescope during the late 2024 apparition. The same solar analog was used for both observations to remove one source of inconsistency. We measured spectral slopes of 2.51% $\pm$ 0.05%/100 nm and 8.13% $\pm$ 0.05%/100 nm at the two different rotational phases. The first of these measurements was serendipitously obtained during an occultation of Menoetius by Patroclus. Although the statistical significance of the spectral slope discrepancy persists even after considering possible systematic errors stemming from differences in slit position angles and air masses between the asteroid and solar analog exposures, we consider this report of variability to be tentative. We briefly explore several scenarios that could explain the measured spectral slope variability. Additional follow-up observations are necessary to definitively confirm and characterize any inhomogeneities across the surface, which will have major implications for the 2033 flyby of Patroclus-Menoetius by the Lucy spacecraft. + oai:arXiv.org:2512.16714v1 + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.3847/PSJ/ae2750 + Ian Wong et al 2025 Planet. Sci. J. 6 295 + Ian Wong, William M. Grundy, Joshua P. Emery, Richard P. Binzel, Oriel A. Humes, Simone Marchi, Pippa M. Molyneux, Keith S. Noll + + + A finite temperature framework for quark matter with color-superconducting phases + https://arxiv.org/abs/2512.16720 + arXiv:2512.16720v1 Announce Type: new +Abstract: Current observations of neutron stars and measurements of gravitational waves only provide constraints on the zero temperature ($T=0$) equation of state (EoS) of dense matter. The detection of the post-merger gravitational-wave signal from a binary neutron star merger would additionally provide access to finite-temperature properties of the EoS which contain more information about the composition and the interactions of dense matter than the cold EoS alone. In particular deconfined quark matter may be probed by its characteristic finite temperature effects. This is especially the case for color-superconducting phases, in which the quasiparticle contribution to the thermal pressure is exponentially suppressed at low temperatures. Here we develop a new finite $T$ framework to model the thermal EoS for dense quark matter based on the cold quark matter EoS which is useful for numerical relativity simulations. We test the validity of the framework against a three-flavor NJL mean-field calculation, both with and without diquark pairing. We find that even for the complicated phase diagram of the NJL model including multiple different phases the framework is accurate to the few percent level for temperatures up to $T\sim 50\,$MeV. + oai:arXiv.org:2512.16720v1 + astro-ph.HE + gr-qc + hep-ph + nucl-th + Fri, 19 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Dily Duan Yi Ong, Francesco D'Eugenio, Roberto Maiolino, Santiago Arribas, Francesco Belfiore, Enrica Bellocchi, Stefano Carniani, Sara Cazzoli, Giovanni Cresci, Andrew Fabian, Wako Ishibashi, Filippo Mannucci, Alessandro Marconi, Helen Russell, Eckhard Sturm, Giacomo Venturi + Hosein Gholami, Marco Hofmann, D\'ebora Mroczek, Jacquelyn Noronha-Hostler - Evidence of galaxy cluster rotation in the cosmic microwave background - https://arxiv.org/abs/2512.10951 - arXiv:2512.10951v1 Announce Type: new -Abstract: We report the first robust evidence for the rotational kinematic Sunyaev-Zel'dovich (rkSZ) effect, produced by the Thomson scattering of cosmic microwave background (CMB) photons off rotating intracluster gas. By combining CMB intensity and polarization measurements from the $\it{Planck}$ satellite with spectroscopic member-galaxy redshifts from the Sloan Digital Sky Survey in a sample of 25 X-ray cross-matched, low-redshift ($0.02< z< 0.09)$, massive ($10^{13.9}\lesssim M_{\rm 500c}/M_\odot \lesssim 10^{14.6}$) galaxy clusters, we detect a dipolar rkSZ signature aligned with the estimated rotation direction of each cluster, ruling out a chance fluctuation at 99.98% confidence (3.6$\sigma$). The significance of this measurement is enhanced by several new methodological improvements for isolating the rkSZ signal from primary CMB fluctuations and noise. The amplitude and shape of the signal are qualitatively consistent with predictions from state-of-the-art hydrodynamical simulations. These results establish a new tool with which to probe the dynamical state of galaxy clusters using CMB data. - oai:arXiv.org:2512.10951v1 + A faint M$_{\rm UV} = -14.5$ Lyman continuum leaker in the reionization epoch: unprecedented Ly$\alpha$ properties at z=5.725 + https://arxiv.org/abs/2512.16728 + arXiv:2512.16728v1 Announce Type: new +Abstract: We report the unprecedented Ly$\alpha$ properties of AMORE6, an extremely metal-poor ($12+\log({\rm O/H}) < 6$), low-mass ($M_\star = 4.4\times10^{5}\,M_\odot$), and ultra-compact (effective radius $\lesssim30$ pc) dwarf galaxy at $z=5.7253$, gravitationally lensed by the cluster A2744. A prominent, narrow, and nearly-symmetric Ly$\alpha$ emission line is detected at the systemic redshift (the latter traced by H$\beta$, from JWST/NIRCam slitless spectroscopy), with rest-frame $EW=150\pm10$ \r{A}, $\rm FWHM=58\pm1$ km s$^{-1}$, and a slight asymmetry, resulting in a $\rm \sim10\%$ flux excess in the red wing of the line. The negligible velocity offset from systemic ($dv = 4\pm67$ km s$^{-1}$, $3\sigma$ uncertainty), together with the sharpness and symmetry of the profile, indicates minimal radiative transfer effects implying a neutral hydrogen column density consistent with an optically thin medium, compatible with a non-zero ionizing photon escape fraction. If indirect spectral diagnostics calibrated at $z<4.5$ remain the only viable tools to identify LyC leakers during reionization, then based on its strongest indicator (Ly$\alpha$), AMORE6 stands out as one of the most compelling LyC-leaking candidates yet discovered in the reionization epoch. + oai:arXiv.org:2512.16728v1 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + M. Messa, E. Vanzella, T. Morishita, M. Stiavelli, T. Treu, P. Bergamini, Z. Liu, A. Zanella, A. Bolamperti, A. Verhamme, T. Garel, C. Grillo, P. Rosati + + + Current observations favour phantom-enhanced nature of dark energy + https://arxiv.org/abs/2512.16731 + arXiv:2512.16731v1 Announce Type: new +Abstract: Our study shows that the more a dark energy model allows the equation of state to become phantom-like toward the past, the better it fits current observations which also may lead to stronger statistical tension with $\Lambda$CDM. In particular, models with greater flexibility in their redshift evolution, such as power-law type forms, are mildly preferred over more restrictive parametrizations with similar parameter dimensionality. For the dataset including DESY5, the deviation from $\Lambda$CDM reaches a significance of $6.26\sigma$. These results indicate that present data are sensitive to enhanced phantom behaviour and provide clear guidance for constructing phenomenologically viable dark energy parametrizations. + oai:arXiv.org:2512.16731v1 astro-ph.CO + gr-qc + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Md. Wali Hossain + + + The WINTER Observatory: A One-Degree InGaAs Survey Camera to study the Transient Infrared Sky + https://arxiv.org/abs/2512.16753 + arXiv:2512.16753v1 Announce Type: new +Abstract: The Wide-field Infrared Transient Explorer (WINTER) is a new near-infrared time-domain survey instrument installed on a dedicated 1-meter robotic telescope at Palomar Observatory. The project takes advantage of the recent technology advances in time-domain astronomy, robotic telescopes, large-format sensors, and rapid data reduction and alert software for timely follow up of events. Since June of 2023, WINTER robotically surveys the sky each night to a median depth of J_AB = 18.5 mag, balancing a variety of science programs including searching for kilonovae from gravitational-wave alerts, blind surveys to study galactic and extragalactic transients and variables, and building up reference images of the near-infrared sky. The project also serves as a technology demonstration for new large-format Indium Gallium Arsenide (InGaAs) sensors for near-infrared photometry without cryogenic cooling. WINTER's custom camera combines six InGaAs sensors with a novel tiled fly's-eye optical design to cover a >1 degree-squared field of view with 1 arcsecond pixels in the Y-, J-, and shortened-H-band filters (0.9 - 1.7 micron). This paper presents the design, performance, and early on-sky science of the WINTER observatory. + oai:arXiv.org:2512.16753v1 + astro-ph.IM astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.HE + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Danielle Frostig, Nathan Lourie, Viraj Karambelkar, Mansi M. Kasliwal, Andrew Malonis, Robert A. Simcoe, Robert Stein, John W. Baker, Kevin Burdge, Rick Burruss, Curt Corcoran, Kishalay De, Gabor Furesz, Nicolae Ganciu, Kari Haworth, Carolyn M. Heffner, Erik Hinrichsen, Jill Juneau, Geoffrey Mo, Josiah Purdum, Sam Rose, Cruz Soto, Jeffry Zolkower + + + N-body interactions and collisions in circumstellar disks for planar and inclined binary star configurations + https://arxiv.org/abs/2512.16758 + arXiv:2512.16758v1 Announce Type: new +Abstract: The discovery of exoplanets in binary star systems-now numbering about 850 of the nearly 4,600 known exoplanet systems-raises questions about whether observational bias or stellar companions inhibit planet formation. While most studies on terrestrial planet formation assume planar configurations, wide binaries likely feature random inclinations, potentially disrupting planet-forming disks. This study explores the evolution of embryo-planetesimal disks in S-type motion in misaligned binary systems, focusing on the stage after the gas phase when terrestrial planet formation begins and gravitational interactions dominate. Using our GPU-accelerated N-body code GANBISS, we simulate disks with 2,000 planetesimals and 25 planetary embryos, studying the influence of the planetesimals on the evolution of the embryos and tracking their growth through collisions. After the simulations, we analyse collision outcomes with an analytical model. Moreover, for certain inclined binary configurations, we compare dynamically excited (perturbed by the secondary star) with cold disks in inclined configurations, as the distribution after the gas phase in misaligned binaries remains unclear. Our simulations reveal two key outcomes: (i) embryos migrate slightly inward in misaligned systems, and (ii) The initial large oscillations in embryos' inclinations and nodes around the respective values of the secondary star dampen over time. Collision analysis shows distinct differences: planar systems favour accretive collisions, while inclined configurations exhibit more destructive events. These findings underscore the sensitivity of planet formation dynamics to binary star alignment and initial disk conditions. + oai:arXiv.org:2512.16758v1 + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/publicdomain/zero/1.0/ - Samuel Goldstein, J. Colin Hill + http://creativecommons.org/licenses/by/4.0/ + Maximilian Zimmermann, Elke Pilat-Lohinger - CWTHF: Subhalo Identification with Continuous Wavelet Transform - https://arxiv.org/abs/2512.09359 - arXiv:2512.09359v1 Announce Type: cross -Abstract: With advances in cosmology and computer science, cosmological simulations now resolve structures in increasingly fine detail. As key tracers of hierarchical structure formation, subhalos are among the most important objects within these simulations. In our previous work, we established that the continuous wavelet transform (CWT) can effectively extract clustering information and serve as a robust halo finder. Here, we extend the CWT framework to subhalo identification by adapting the CWTHF (Continuous Wavelet Transform Halo Finder) code. This extension extends the unbinding procedure, which enables the reliable identification of gravitationally bound substructures. The algorithm identifies density peaks within known halos or subhalos and segments the surrounding volume accordingly. Once a new subhalo is registered, its position is recorded to prevent duplicate detection. We validate our approach using the TNG50-2 and TNG100-1 simulations, as well as a single Friends-of-Friends (FOF) halo, by comparing the resulting CWT catalog against the reference SUBFIND catalog. Because the method inherits the original computational framework, our subhalo finder maintains a favorable linear time complexity of $\mathcal{O}(N)$. - oai:arXiv.org:2512.09359v1 + Strategies for Accurate Effective Point Spread Function (ePSF) Modelling on Undersampled Images + https://arxiv.org/abs/2512.16764 + arXiv:2512.16764v1 Announce Type: new +Abstract: Accurate modelling of the effective point spread function (ePSF) is essential for high-precision photometry and astrometry, particularly in undersampled imaging regimes. In this work, we build on a well-established ePSF modelling framework and its commonly used open-source Python implementation and demonstrate that several simple but effective modifications to existing ePSF modelling routines can significantly improve model accuracy. We use synthetic ePSFs to generate simulated datasets of stellar images, allowing us to evaluate the accuracy of ePSF models and determine the scale of the pixel-phase errors in resulting flux and position measurements. We systematically investigate how specific modelling choices affect ePSF accuracy, and evaluate the influence of oversampling, interpolation, gridpoint estimation, smoothing, star-sample distribution, and dithering on photometric precision. We apply our refined ePSF modelling routine to images from the Global Jet Watch observatories, demonstrating its improved ability to recover an accurate ePSF for real astronomical images. Our findings highlight the importance of tailoring the modelling approach to the specific characteristics of the instrument and detector, as well as to the nature of the available imaging data used to construct the ePSF model. These results provide practical guidance for optimising ePSF construction, thereby improving the reliability of photometric and astrometric measurements. + oai:arXiv.org:2512.16764v1 astro-ph.IM + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Emma Godden, Katherine M. Blundell + + + Dark energy and neutrinos along the cosmic expansion history + https://arxiv.org/abs/2512.16781 + arXiv:2512.16781v1 Announce Type: new +Abstract: Recent cosmological measurements are hinting that dark energy may evolve, with its equation of state, $w_\mathrm{DE}$, even showing oscillatory patterns. In this work, we employ a model-independent approach to jointly reconstruct $w_\mathrm{DE}$ and the sum of neutrino masses, $\sum m_\nu$, adopting the PCHIP method with seven fixed nodes in which we allow the two parameters to vary. We employ CMB, Baryon Acoustic Oscillations and Supernovae Ia data to constrain the values of $w_\mathrm{DE}$ and $\sum m_\nu$ at each node. We conduct three different analyses in which we reconstruct $w_\mathrm{DE}$: one with fixed $\sum m_\nu=0.06~\mathrm{eV}$; one in which we allow $\sum m_\nu$ to vary, and one in which we also reconstruct $\sum m_\nu$ using the PCHIP method. We find the dark energy equation of state to be consistent with the cosmological constant scenario, except when including DESI data and allowing for phantom crossing, where we find a $95\%$ CL deviation from $w_\mathrm{DE}=-1$ around $z\sim1.2$. For neutrino masses, we obtain looser constraints when focusing on phantom dark energy, that show further early and late relaxation when reconstructing the mass via the PCHIP method. + oai:arXiv.org:2512.16781v1 astro-ph.CO + hep-ph + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Pietro Ghedini, Rasmi Hajjar, Olga Mena + + + SNR 1987A : Spitzer data from days 6000 to 8000 revisited + https://arxiv.org/abs/2512.16801 + arXiv:2512.16801v1 Announce Type: new +Abstract: An excess emission has been observed by Spitzer in the [3, 5] micron range of the SNR 1987A spectrum. It is generally argued that this excess could be due to the presence of warm amorphous carbon dust in the equatorial ring (ER) around the supernova, but the proposed models all have problems. This prompted us to present an alternative view on the interpretation of the Spectral Energy Distribution (SED) of SNR 1987A from the near-IR wavelengths to the radio frequencies (from 3 micron up to 1.4 GHz), between 6000 and 8000 days after outburst. We argue that the origin of that excess could be attributed instead to a free-free emission. We show that under very specific conditions (the free-free is self-absorbed at a cut-off frequency imposed by the mass of the emitting region), it could be produced by collisional heating of the gas. We then discuss the time evolution of the various components of the SED. We establish a linear relationship between the growth of the warm carbon dust mass and that of the silicates dust during the analyzed period. Finally, we build the Spitzer light curves and we show that our models reproduce the observations pretty well, although our study clearly favors the free-free case. In conclusion, we argue that the free-free model provides a formally very good description of the data, however the model does require some very specific parameter choices, and results in an unusually low temperature for the ionized gas. + oai:arXiv.org:2512.16801v1 + astro-ph.SR astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 - cross + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Patrice Bouchet, Ren\'e Gastaud, Alain Coulais, Richard G. Arendt + + + Future Dark Energy Constraints from Atomic Clocks + https://arxiv.org/abs/2512.16804 + arXiv:2512.16804v1 Announce Type: new +Abstract: We show that atomic clock measurements provides an exceptionally sensitive Solar System probe of scalar tensor dark energy. By connecting variations in Newton's constant and differential clock drifts to the dynamics of a single dark energy scalar, we derive a direct constraint on the present day equation of state and our results force any locally coupled scalar dark energy into a very slowly rolling regime, giving the strongest bounds on the equation of state parameter. This is independent of potential shape or kinetic structure and rules out broad classes of canonical and non canonical models, leaving only near Lambda CDM behavior or fully decoupled fields as viable late time scalar dark energy, thereby leaving cosmological constant and minimally coupled scalar field models as the most consistent dark energy regimes. We also use results from Lunar Laser Ranging and photon trajectories to further strengthen our the depth of our constraints. + oai:arXiv.org:2512.16804v1 + astro-ph.CO + gr-qc + hep-th + Fri, 19 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by/4.0/ - Minxing Li, Yun Wang, Ping He + Oem Trivedi - Lateral Deformation of Large-scale Coronal Mass Ejections during the Transition from Non-radial to Radial Propagation - https://arxiv.org/abs/2512.09937 - arXiv:2512.09937v1 Announce Type: cross -Abstract: Many coronal mass ejections (CMEs) initially propagate non-radially, and then transition to radial propagation in the corona. This directional transition is a significant process that determines a CME's space weather effects but remains poorly understood. Based on multi-wavelength observations, we investigate the transition from non-radial to radial propagation in the low corona for two large-scale CMEs from the same active region on the solar limb. In the beginning, both CMEs move in a non-radial direction, beneath a system of overlying loops that are roughly parallel to the flux-rope axis. The CMEs laterally deform by bulging their upper flanks in the non-radial stage toward the higher corona, which results in the transition to a radial propagation direction approximately 25$^\circ$ away from the eruption site. After the directional transition, the non-radial-stage upper flank becomes the leading edge in the radial stage. Although the overlying loops do not strap over the flux rope, their strong magnetic tension force constrains the radial expansion of part of the CME during the transition by acting on the flux-rope legs. A major portion of the filament is displaced to the southern part of a CME in the radial stage, which implies the complexity of observational CME features. This study presents the first investigation of the lateral deformation during the transition of CMEs from non-radial to radial in the low corona, and makes an essential contribution to the complete CME evolution picture. - oai:arXiv.org:2512.09937v1 - physics.space-ph - astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 - cross + Connecting current and future dual AGN searches to LISA and PTA gravitational wave detections + https://arxiv.org/abs/2512.16844 + arXiv:2512.16844v1 Announce Type: new +Abstract: Dual active galactic nuclei (DAGN) mark an observable stage of massive black hole (MBH) pairing in galaxy mergers and are precursors to the MBH binaries that generate low-frequency gravitational waves. Using the large-volume ASTRID cosmological simulation, we construct DAGN catalogs matched to current (COSMOS-Web, DESI) and forthcoming (AXIS, Roman) searches. With realistic selection functions applied, ASTRID reproduces observed dual fractions, separations, and host-galaxy properties across redshifts. We predict a substantial population of small-separation (<5 kpc) duals that current surveys fail to capture, indicating that the apparent paucity of sub-kpc systems in COSMOS-Web is driven primarily by selection effects rather than a physical deficit. By following each simulated dual forward in time, we show that dual AGN are robust tracers of MBH mergers: ~30-70% coalesce within $\lesssim 1$ Gyr, and 20-60% of these mergers produce gravitational-wave signals detectable by LISA. Duals accessible to AXIS and Roman are the progenitors of ~10% of low-redshift LISA events and ~30% of the PTA-band stochastic background. Massive green-valley galaxies with moderate-luminosity AGN, together with massive star-forming hosts containing bright quasars at $z>1$, emerge as the most likely environments for imminent MBH binaries. These results provide a unified cosmological framework linking dual AGN demographics, MBH binary formation, and gravitational-wave emission, and they identify concrete, high-priority targets for coordinated electromagnetic and GW searches in upcoming multi-messenger surveys. + oai:arXiv.org:2512.16844v1 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by/4.0/ - Huidong Hu (NSSC, CAS), Chong Chen (HUTB, China), Yiming Jiao (NSSC, CAS), Bei Zhu (Space Eng. U., China), Rui Wang (NSSC, CAS), Xiaowei Zhao (NSMC, CMA), Liping Yang (NSSC, CAS) + Nianyi Chen, Yihao Zhou, Ekaterine Dadiani, Tiziana Di Matteo, Cici Wang, Antonella Palmese, Yue Shen, Junyao Li, Adi Foord, Simeon Bird, Yueying Ni, Yanhui Yang, Rupert Croft - Two-dimensional PIC simulation of collective Thomson scattering in a beam-plasma system - https://arxiv.org/abs/2512.09949 - arXiv:2512.09949v1 Announce Type: cross -Abstract: Collective Thomson scattering (CTS) in a beam-plasma system is reproduced by using 2D PIC simulations and the characteristics of the scattered wave spectrum are examined. By formulating the geometric shape of the scattered wave spectrum in wave number space, where the velocity vector of the beam component and the wave vectors of the incident and scattered waves are arbitrary, it is demonstrated that the spectrum in 2D wave number space becomes asymmetric. The spectrum of scattered waves propagating in a specific direction is presented as a function of wavelength to show that the electron (ion) feature is amplified and becomes asymmetric or distorted when Buneman (ion acoustic) instability occurs. An additional simulation is conducted for a weak, linearly stable beam-plasma system with a hot beam, and confirmed that the obtained scattered wave spectrum shows asymmetric feature. The results are expected to be applicable to the interpretation of radar observations of ionospheric plasmas as well as CTS measurements in laboratory plasmas. - oai:arXiv.org:2512.09949v1 - physics.plasm-ph + BeppoSAX-WFC catalog of fast X-ray transients + https://arxiv.org/abs/2512.16845 + arXiv:2512.16845v1 Announce Type: new +Abstract: We performed a search for fast X-ray transients (FXTs), with durations longer than one second and less than one day, through data of the Wide Field Camera (WFC) instrument onboard the BeppoSAX X-ray observatory collected between June 1996 and April 2002. (..) We focused our search on gamma-ray bursts (GRBs), X-ray flashes (XRFs), X-ray flares from high-mass X-ray binaries and stellar flares, while Type-I and II X-ray bursts from Galactic neutron stars were excluded. 149 such fast transient events were detected. 63 of these are new to the literature. 38 flares are identified with 22 nearby stars. Three stars have never been seen flaring before in X-rays or optical (NLTT 51688, GR Dra and UCAC4 255-003783). We find that the MeV transient GRO J1753+57 is most likely the same object as GR Dra rather than an AGN as previously thought. Eleven flares were detected from known high-mass X-ray binaries with irregular wind accretion (four of which are of the subclass of supergiant fast X-ray transients). 100 GRBs were identified of which 24 have not been published before. We classify 37% of the X-ray detected GRBs as XRFs with relatively large X-ray to gamma-ray flux ratio, gamma-rays being measured with the BeppoSAX Gamma Ray Burst Monitor. The duration/spectral hardness distribution of all FXTs is bimodal, separating the group roughly in transients shorter and longer than 1 ksec and with relatively hard and soft spectra, respectively. We identify the 'short' FXTs as GRBs and XRFs and the `long' FXTs as flares from nearby late-type stars and X-ray binaries. The BeppoSAX-WFC FXT sample is found to be consistent with the one observed by Einstein Probe, when the sensitivity of the two instruments is taken into account. + oai:arXiv.org:2512.16845v1 astro-ph.HE - physics.space-ph - Fri, 12 Dec 2025 00:00:00 -0500 - cross + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + J. J. M. in 't Zand (SRON), C. Guidorzi (U. Ferrara,INAF-OAS), J. Heise (SRON), L. Amati (INAF-OAS), E. Kuulkers (ESA), F. Frontera (U. Ferrara,INAF-OAS), G. Gianfagna (INAF-IAPS), L. Piro (INAF-IAPS) + + + A Radio Search for Star-Planet Interaction in TOI-540 and SPECULOOS-3 + https://arxiv.org/abs/2512.16852 + arXiv:2512.16852v1 Announce Type: new +Abstract: We present the first targeted centimeter-band radio observations of two recently-discovered exoplanet systems that are prime candidates for magnetic star-planet interaction (SPI): TOI-540 and SPECULOOS-3. The targets were selected due to the small orbital separation of their known planets, as well as for indications of stellar magnetic activity, given that for SPI radio emission may be strongest when a sufficiently magnetized star hosts a close-in planet. The deep, multi-epoch Very Large Array (SPECULOOS-3) and MeerKAT (TOI-540) observations yield non-detections, with $3\sigma$ limits of $\lesssim 7.5$ $\mu$Jy ($4-8$ GHz) and $\lesssim 30-80$ $\mu$Jy ($0.8-1.7$ GHz), respectively. For SPECULOOS-3 b we rule out observable SPI for most of its orbit, while for TOI-540 b we sample a narrower range, around planetary transit. We model possible planetary magnetic field strength constraints for both systems, and conclude that our observations are sensitive enough to sample SPI emission in these systems if present and directed at us, even for a planetary field of only $\sim 1$ G. + oai:arXiv.org:2512.16852v1 + astro-ph.EP + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by/4.0/ - Yuma Sato, Shuichi Matsukiyo + Kevin N. Ortiz Ceballos, Yvette Cendes, Edo Berger - The meaning of "Big Bang" - https://arxiv.org/abs/2512.09950 - arXiv:2512.09950v1 Announce Type: cross -Abstract: What does ``Big Bang'' actually mean? What was the origin of these two words? It has often been said that the expression ``Big Bang'' began as an insult. Even if this were true, it would be just an irrelevant part of the whole issue. There are many more aspects hidden under this name, and which are seldom explained. They will be discussed in this work. In order to frame the analysis, help will be sought from the highly authoritative voices of two exceptional writers: William Shakespeare and Umberto Eco. Both Shakespeare and Eco have explored the tension existing between words and the realities they name. With the conclusion that names are, in general, just labels, simple stickers put to identify things. And this includes those given to great theorems or spectacular discoveries. Not even ``Pythagoras' theorem'' was discovered by Pythagoras, as is now well-known. Stigler's law of eponymy is recalled to further substantiate those statements. These points will be at the heart of the investigation carried out here, concerning the very important concept of ``Big Bang''. Everybody thinks to know what ``the Big Bang'' is, but only very few do know it, in fact. When Fred Hoyle first pronounced these two words together, on a BBC radio program, listeners were actually left with the false image that Hoyle was trying to destroy. That is, the tremendous explosion of Lema\^itre's primeval atom (or cosmic egg), which scattered all its enormous matter and energy content throughout the rest of the Universe. This image is absolutely wrong! As will be concluded, today the label ``Big Bang'' is used in several different contexts: (a) the Big Bang Singularity; (b) as the equivalent of cosmic inflation; (c) speaking of the Big Bang cosmological model; (d) to name a very popular TV program; and more. - oai:arXiv.org:2512.09950v1 - physics.pop-ph + Robust CMB B-mode analysis with Needlet-ILC and simulation-based inference + https://arxiv.org/abs/2512.16869 + arXiv:2512.16869v1 Announce Type: new +Abstract: We explore a novel analysis framework for parameter inference with large-scale CMB polarization data. Our method uses simulation-based inference combined with the needlet internal linear combination (NILC) algorithm and cross-correlation-based statistics to compress the data into a vector that is robust to model misspecification and small enough to be amenable to neural posterior estimation with normalizing flows. By leveraging this compressed data representation, our method enables the robust use of the anisotropic and non-Gaussian information in the foreground fields to more accurately separate the CMB polarization signal from these contaminants. Using an idealized ground-based experimental setup inspired by the Simons Observatory Small Aperture Telescopes, we demonstrate improved statistical constraining power for the tensor-to-scalar ratio $r$ compared to the (constrained) NILC algorithm and improved robustness to complex foregrounds compared to other techniques in the literature. Trained on a relatively simple semi-analytical foreground model, the method yields unbiased $r$ results across a range of PySM Galactic foreground simulations, including the high-complexity d12 model, for which we obtain $r=(1.09 \pm 0.27)\cdot 10^{-2}$ for input $r=0.01$ and sky fraction $f_{\mathrm{sky}} = 0.21$. We thus demonstrate the feasibility and advantages of a complete, maps-to-parameters, simulation-based analysis of large-scale CMB polarization for current ground-based observatories. + oai:arXiv.org:2512.16869v1 astro-ph.CO - gr-qc - math-ph - math.MP - physics.hist-ph - Fri, 12 Dec 2025 00:00:00 -0500 - cross + astro-ph.IM + Fri, 19 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Adriaan J. Duivenvoorden, Kristen Surrao, Adrian E. Bayer, Alexandre E. Adler, Nadia Dachlythra, Susanna Azzoni, J. Colin Hill + + + Discovering gravitational waveform distortions from lensing: a deep dive into GW231123 + https://arxiv.org/abs/2512.16916 + arXiv:2512.16916v1 Announce Type: new +Abstract: Gravitational waves (GWs) are unique messengers as they travel through the Universe without alteration except for gravitational lensing. Their long wavelengths make them susceptible to diffraction by cosmic structures, providing an unprecedented opportunity to map dark matter substructures. Identifying lensed events requires the analysis of thousands to millions of simulated events to reach high statistical significances. This is computationally prohibitive with standard GW parameter estimation methods. We build on top of state-of-the-art neural posterior algorithms to accelerate the lensed inference from CPU days to minutes with DINGO-lensing. We showcase its capabilities by reanalyzing GW231123, the most promising lensed candidate so far, and find that its statistical significance cannot exceed 4$\sigma$. We observe that 8% of GW231123-like nonlensed simulations favor lensing, which could be explained by the self-similarity of short-duration signals. Still, 58% of GW231123-like lensed simulations have larger support for lensing, showing that higher detection statistics are possible. Although GW231123 exposes the challenges of claiming the first GW lensing detection, our deep-learning methods have demonstrated to be powerful enough to enable the upcoming discovery of lensed GWs. + oai:arXiv.org:2512.16916v1 + astro-ph.CO + hep-ph + Fri, 19 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by/4.0/ - Emilio Elizalde + Juno C. L. Chan, Jose Mar\'ia Ezquiaga, Rico K. L. Lo, Joey Bowman, Lorena Maga\~na Zertuche, Luka Vujeva - Blandford-Znajek Jets and the Total Angular Momentum Evolution of a Black Hole Connected to a Cosmic String - https://arxiv.org/abs/2512.09966 - arXiv:2512.09966v1 Announce Type: cross -Abstract: Rotating black holes with strong magnetic fields lead to an outward energy flux in the form of jets governed by the Blandford-Znajek mechanism. These jets depend on factors such as accretion rate, magnetic flux and the spin of the black hole. When such rotating black holes get attached to a cosmic string, it leads to a further rotational energy extraction, leading to a reduced spin. We consider such a system and investigate the effect this reduced spin has on the jet power and its dependence on the cosmic string tension, $\mu$. It is shown that for a constant magnetic flux and accretion rate, the jet energy flux is inversely proportional to $\mu^2$. Interestingly, the rate of this energy flux varies with time and is again dependent on $\mu$. We also study the total angular momentum evolution of the black hole by considering four major effects: accretion, jets, cosmic string energy extraction and the Bardeen-Petterson effect. Further, we attempt to analyse the condition for the spin-down of a black hole due to these effects and find out that it is possible for both small and large string tensions, with a higher possibility for larger string tensions. Another interesting phenomenon that has been proposed is the alignment of the jet with the cosmic string. Additionally, the Bardeen-Petterson effect also leads to alignment or misalignment of the inner and outer disks depending on the alignment of the string. In this manuscript we propose that these results might have an observable effect and hence could serve as a potential detection method for cosmic strings. - oai:arXiv.org:2512.09966v1 + Density reconstruction from biased tracers: Testing the equivalence principle through consistency relations + https://arxiv.org/abs/2510.13803 + arXiv:2510.13803v1 Announce Type: cross +Abstract: Consistency relations of large-scale structure offer a unique and powerful test of the weak equivalence principle (EP) on cosmological scales. If the EP is violated, different tracers will undergo different accelerations in response to a uniform gravitational field, and this loss of universality manifests as a dipole with a characteristic $1/K$ scale dependence in the squeezed limit of the bispectrum. In this work we show that such a violation can be identified with a particular anti-symmetric {modulation} in the local cross-power spectrum of distinct tracers. Based on this observation, we propose to test the EP using quadratic estimators as a more practical alternative to the conventional approach of directly estimating the bispectrum. We apply our quadratic estimator to a DESI-like survey and forecast constraints on the overall amplitude of EP violation. Including mildly nonlinear scales in our reconstruction ($k_\mathrm{max}\simeq0.15\, h\,\mathrm{Mpc}^{-1}$), we find that our estimator is competitive with the more exhaustive direct bispectrum approach. This means surveys like DESI can already benefit from the quadratic estimator approach. + oai:arXiv.org:2510.13803v1 + astro-ph.CO + astro-ph.IM gr-qc - astro-ph.HE - hep-th - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - 10.1103/58tc-v253 - Journal = Physical Review D, volume = 112, issue = 4, pages = 043034, year = 2025, month = August, publisher = American Physical Society - Ishan Swamy, Deobrat Singh + Lawrence Dam, Omar Darwish - The Eschatian Hypothesis - https://arxiv.org/abs/2512.09970 - arXiv:2512.09970v1 Announce Type: cross -Abstract: The history of astronomical discovery shows that many of the most detectable phenomena, especially detection firsts, are not typical members of their broader class, but rather rare, extreme cases with disproportionately large observational signatures. Motivated by this, we propose the Eschatian Hypothesis: that the first confirmed detection of an extraterrestrial technological civilization is most likely to be an atypical example, one that is unusually "loud" (i.e., producing an anomalously strong technosignature), and plausibly in a transitory, unstable, or even terminal phase. Using a toy model, we derive conditions under which such loud civilizations dominate detections, finding for example that if a society is loud for only $10^{-6}$ of its lifetime, it must emit ${\gtrsim}1$% of its total observable energy budget during that phase to outrun quieter populations. The hypothesis naturally motivates agnostic anomaly searches in wide-field, multi-channel, continuous surveys as a practical strategy for a first detection of extraterrestrial technology. - oai:arXiv.org:2512.09970v1 - physics.pop-ph - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + Towards First Detection of the Solar MSW Transition With JUNO + https://arxiv.org/abs/2512.14824 + arXiv:2512.14824v1 Announce Type: cross +Abstract: Matter-induced neutrino flavor mixing (the Mikheyev-Smirnov-Wolfenstein, or MSW, effect) is a central prediction of the neutrino mixing framework, but it has not been conclusively observed. Direct observation of the energy-dependent MSW transition in the solar electron-neutrino survival probability would solve this, but backgrounds have been prohibitive. We show that our new technique for suppressing muon-induced spallation backgrounds will allow JUNO to measure the MSW transition at $>$4$\sigma$ significance in 10 years. This would strongly support upcoming multi-\$1B next-generation long-baseline experiments and their goals in cementing the neutrino mixing framework. + oai:arXiv.org:2512.14824v1 + hep-ph + astro-ph.HE + hep-ex + nucl-ex + nucl-th + Fri, 19 Dec 2025 00:00:00 -0500 cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - David Kipping + Obada Nairat, John F. Beacom, Kevin J. Kelly, Shirley Weishi Li - Can the 3 neutrino masses really be found using SN 1987A data? - https://arxiv.org/abs/2512.09971 - arXiv:2512.09971v1 Announce Type: cross -Abstract: Neutrino masses remain a significant unsolved problem in physics and their nonzero value proves the Standard Model is incomplete. Currently, the values of the three masses only have upper limits from cosmology and experiments like KATRIN. This paper shows that the SN 1987A neutrino data can remarkably yield values for the three neutrino masses, and not merely upper limits. Although this seemingly preposterous idea was suggested a dozen years ago by the author, here it is demonstrated in a much more convincing manner with many new elements, including a stronger statistical treatment, a theoretical linkage to possible CPT violation, and most importantly, a thorough explanation of why the method used to find the three masses from supernova SN 1987A neutrino data really works. The key to finding the three neutrino masses is realizing why three normally accepted assumotions are unjustified, The three rejected assumptions are:(a) the 5-hr early LSD (Mont Blanc) neutrinos are unrelated to SN 1987A, (b) any masses $>1 eV/c^2$ would be inconsistent with upper limits from KATRIN and other data, and (c) the spread in neutrino emission times from SN 1987A is too great for the method to work. - oai:arXiv.org:2512.09971v1 - hep-ph + Multiple mountains on a pulsar: implications for gravitational waves and the spin-down rate + https://arxiv.org/abs/2512.15200 + arXiv:2512.15200v1 Announce Type: cross +Abstract: A pulsar, i.e., a spinning neutron star, with a deformation could emit gravitational waves continuously. Such continuous waves, which have not been detected yet, will be very useful to study gravitational physics and to probe the extreme physics of neutron stars. While typically such waves from a pulsar are estimated considering an overall stellar ellipticity, there can be multiple irregularities or mountains in the stellar crust that the gravity of the star cannot smooth. In this paper, we consider this realistic situation and compute the strain, power, torque and the pulsar spin-down rate due to multiple mountains supported by the stellar crust. Here, we consider astronomically motivated mountain distributions and use the Brans-Dicke theory of gravity which has three polarization states: two tensors dominated by the time-varying quadrupole moment and one scalar dominated by the time-varying dipole moment. We also give the limiting results for general relativity. + oai:arXiv.org:2512.15200v1 + gr-qc astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - Robert Ehrlich + Paritosh Verma, Sudip Bhattacharyya - Gravitational-wave parameter estimation to the Moon and back: massive binaries and the case of GW231123 - https://arxiv.org/abs/2512.09978 - arXiv:2512.09978v1 Announce Type: cross -Abstract: We study the prospects of the Lunar Gravitational-Wave Antenna (LGWA), a proposed deci-Hz GW detector, to observe binary black holes (BBHs) and enable multiband science with ground-based detectors. We assess the detectability of the events observed by current instruments up to the GWTC-4.0 data release, and of simulated populations consistent with the latest reconstruction by the LIGO-Virgo-KAGRA Collaboration. We find that LGWA alone would have been able to observe more than one third of the events detected so far, and that it could detect $\sim\!90$ events merging in the ground-based band per year out to redshifts $z\sim3-5$. Current detectors at design sensitivity and 100% duty cycle could detect thousands of BBHs per year, with one to a few hundred multiband counterparts in LGWA. Third-generation (3G) detectors can observe most of the BBHs detected by LGWA merging in their frequency band in the simulated mass range $7\,{\rm M}_\odot\lesssim M_{\rm tot}\lesssim 600\,{\rm M}_\odot$, enabling systematic joint analyses of hundreds of events. The short time to merger from the deci-Hz band to the Hz-kHz band (typically months to a year) allows for early warning, targeted follow-up, and archival searches. Multiband observations of intermediate-mass BBHs in the deci-Hz band are particularly promising. We perform an injection study for a GW231123-like system (the most massive BBH detection to date, which accumulates $\sim 10^5$ inspiral cycles in LGWA) and show that deci-Hz observations can measure the chirp mass even better than 3G instruments and yield good sky localization and inclination measurement, even with a single observatory. Opening the deci-Hz band would substantially improve the prospects of GW astronomy for intermediate-mass BBHs. - oai:arXiv.org:2512.09978v1 + GRHayL: a modern, infrastructure-agnostic, extensible library for GRMHD simulations + https://arxiv.org/abs/2512.15846 + arXiv:2512.15846v1 Announce Type: cross +Abstract: Interpreting multi-messenger signals from neutron stars and black holes requires reliable general-relativistic magnetohydrodynamics (GRMHD) simulations across rapidly evolving high-performance-computing platforms, yet key algorithms are routinely rewritten within infrastructure-specific numerical-relativity codes, hindering verification and reuse. We present the General Relativistic Hydrodynamics Library (GRHayL), a modular, infrastructure-agnostic GR(M)HD library providing conservative-to-primitive recovery, reconstruction, flux/source and induction operators, equations of state, and neutrino leakage through an intuitive interface. GRHayL refactors and extends the mature IllinoisGRMHD code into reusable pointwise and stencil-wise kernels, enabling rapid development and cross-code validation in diverse frameworks, while easing adoption of new microphysics and future accelerators. We implement the same kernels in the Einstein Toolkit (Carpet and CarpetX) and BlackHoles@Home, demonstrating portability with minimal duplication. Validation combines continuous-integration unit tests with cross-infrastructure comparisons of analytic GRMHD Riemann problems, dynamical Tolman-Oppenheimer-Volkoff evolutions, and binary neutron-star mergers, showing comparable or improved behavior over legacy IllinoisGRMHD and established Einstein Toolkit codes. + oai:arXiv.org:2512.15846v1 gr-qc + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Samuel Cupp, Leonardo R. Werneck, Terrence Pierre Jacques, Samuel Tootle, Zachariah B. Etienne + + + Cosmological Neutron Stars Produce Diffuse Axion X-Ray Signatures + https://arxiv.org/abs/2512.15849 + arXiv:2512.15849v1 Announce Type: cross +Abstract: Axion-like particles can be abundantly produced through scattering processes in the cores of neutron stars (NSs). If they are ultralight ($m_a \lesssim 10^{-4}$ eV), then they can efficiently convert to detectable photons in the external NS magnetospheres, and if they are heavy ($m_a \gtrsim 1$ eV), then they can decay into photons before reaching Earth. In this work, we search for the resulting X-ray signatures from both of these channels summing over the $\textit{cosmological}$ NS population. We compare the predicted axion-induced X-ray signal to the cosmic X-ray background today as measured by a number of instruments such as NuSTAR, HEAO, Swift, and INTEGRAL. We model the axion-induced signal using NS cooling simulations and magnetic field evolution models. We find no evidence for axions and derive strong constraints for both ultralight and heavy axion scenarios, covering new parameter space for the axion-photon and axion-nucleon couplings. Our results rule out the axion-explanation of the Magnificent Seven X-ray excess from nearby isolated NSs. + oai:arXiv.org:2512.15849v1 + hep-ph astro-ph.CO astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - Francesco Iacovelli, Jacopo Tissino, Jan Harms, Emanuele Berti + Orion Ning, Kailash Raman, Benjamin R. Safdi - Dark matter mounds from the collapse of supermassive stars: a general-relativistic analysis - https://arxiv.org/abs/2512.09985 - arXiv:2512.09985v1 Announce Type: cross -Abstract: Recent work has highlighted the importance of a fully relativistic treatment of the dephasing of gravitational waves induced by dark-matter overdensities in extreme mass-ratio inspirals (EMRIs). However, a general-relativistic description of the dark matter phase-space distribution is currently available only for the case of a dark matter "spike" arising from adiabatic black hole growth. Here we develop a fully general-relativistic formalism for the more realistic scenario in which a supermassive stellar progenitor collapses to a black hole and produces a shallower dark matter overdensity, or "mound". We follow self-consistently the evolution of the supermassive star, its collapse, and the subsequent growth of the resulting black hole, together with the collisionless dark matter orbits. We find that in the regime where the collapse becomes non-adiabatic, the dark matter distribution function is significantly reshaped, with a clear depletion in the low-binding-energy region of phase space. Our results provide a more realistic prediction for the dark matter phase-space distribution around supermassive black holes, which is an essential step in our programme to use future EMRI observations to extract information about both the nature of dark matter and the formation history of the black hole. - oai:arXiv.org:2512.09985v1 + Particle Production by Time-Varying Dark Energy and the End of Cosmic Expansion + https://arxiv.org/abs/2512.15860 + arXiv:2512.15860v1 Announce Type: cross +Abstract: We consider various possible consequences of time-varying dark energy due to a quintessence scalar field whose energy density is partially converted to particles as the field evolves down its potential. This particle production acts as a source of thermal friction on the field that can make it difficult to distinguish whether dark energy is due to a radiating field rolling down a steep potential, a purely self-interacting field moving down a flatter potential, or a cosmological constant. By reducing the acceleration of the scalar field, thermal friction increases the amount of accelerated expansion and can cause a sizable bump in the quintessence equation of state. We take special interest in the case where a steep potential rapidly changes from positive to negative as the field evolves, resulting in the end of cosmic expansion and the beginning of contraction. Even in this case, we find that thermal friction lengthens the period of accelerated expansion and consequently delays the end of cosmic expansion, making it challenging to detect the impending transition to contraction using conventional cosmological tests. However, particle production can also provide alternative avenues for detection by generating a background of thermal dark radiation, partly comprised of neutrinos or other particles, whose energy density exceeds the remnant photon energy density. + oai:arXiv.org:2512.15860v1 gr-qc astro-ph.CO - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + hep-th + Fri, 19 Dec 2025 00:00:00 -0500 cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Roberto Caiozzo, Gianfranco Bertone, Piero Ullio, Rodrigo Vicente, Bradley J. Kavanagh, Daniele Gaggero + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Nicolas Patino, Paul J. Steinhardt - Constraining Gravitational Dark Matter with LHAASO and Fermi-LAT - https://arxiv.org/abs/2512.09997 - arXiv:2512.09997v1 Announce Type: cross -Abstract: We use diffuse Galactic high energy gamma ray data from LHAASO and Fermi-LAT to constrain gravitationally produced decaying dark matter (DM). Focusing on four benchmark candidates: a dark photon, a heavy right-handed neutrino (RHN), a pseudo-Nambu-Goldstone boson (pNGB), and a non-minimally coupled scalar we derive bounds on the DM mass and its couplings to the visible sector. For dark photons, RHNs, and pNGBs, the combined data constrain the relevant interaction strength to $\lesssim\mathcal{O}(10^{-30})$ for DM masses $\gtrsim\mathcal{O}$(TeV), while the non-minimally coupled scalar is limited to $\lesssim\mathcal{O}(10^{-10})$. Moreover, photon-dark photon oscillations yield strong constraints for massive dark photon beyond 10 GeV, closing a region of parameter space previously left unconstrained. - oai:arXiv.org:2512.09997v1 + Kination and the Inert Doublet Model + https://arxiv.org/abs/2512.15864 + arXiv:2512.15864v1 Announce Type: cross +Abstract: The inert doublet model is a two-Higgs-doublet extension of the standard model that provides a minimal and versatile framework for frozen-out dark matter. Assuming standard cosmology, if the dark matter mass ranges between approximately 120 GeV and 500 GeV then it turns out to be underabundant, as gauge interactions render its annihilation too efficient. In this work, we show that this mass window becomes allowed in cosmological scenarios where dark matter freeze-out occurs during a period with a stiff equation of state, $w > 1/3$, such as kination. This predictive setup satisfies all current experimental constraints while remaining within the reach of upcoming detection efforts. + oai:arXiv.org:2512.15864v1 hep-ph astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 cross - http://creativecommons.org/licenses/by/4.0/ - Basabendu Barman, Arindam Das, Prantik Sarmah, Rakesh Kumar SivaKumar + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Genevi\`eve B\'elanger, Nicol\'as Bernal, Andreas Goudelis, Alexander Pukhov - Stationary Stars Are Axisymmetric in Higher Curvature Gravity - https://arxiv.org/abs/2512.10343 - arXiv:2512.10343v1 Announce Type: cross -Abstract: The final equilibrium stage of stellar evolution can result in either a black hole or a compact object such as a white dwarf or neutron star. In general relativity, both stationary black holes and stationary stellar configurations are known to be axisymmetric, and black hole rigidity has been extended to several higher curvature modifications of gravity. In contrast, no comparable result had previously been established for stationary stars beyond general relativity. In this work we extend the stellar axisymmetry theorem to a broad class of diffeomorphism invariant metric theories. Assuming asymptotic flatness and standard smoothness requirements, we show that the Killing symmetry implied by thermodynamic equilibrium inside the star uniquely extends to the exterior region, thereby enforcing rotational invariance. This demonstrates that axisymmetry of stationary stellar configurations is not a feature peculiar to Einstein gravity but a universal property of generally covariant gravitational theories, persisting even in the presence of higher curvature corrections. - oai:arXiv.org:2512.10343v1 + Modeling the frequency-domain ringdown amplitude of comparable-mass mergers with greybody factors + https://arxiv.org/abs/2512.15877 + arXiv:2512.15877v1 Announce Type: cross +Abstract: It was recently shown that, in a binary coalescence, the greybody factor of the remnant black hole modulates the post-merger ringdown signal. In this work, we demonstrate that a simple four-parameter model based on the greybody factor accurately reproduces the frequency-domain amplitude of a large set of comparable-mass, aligned-spin numerical relativity waveforms from the SXS catalog, achieving mismatches of order ${\cal O}(10^{-5})$ and improving existing models by roughly two orders of magnitude. We also identify the optimal initial frequency for applying the model in the frequency domain and provide analytical fits of the model parameters in terms of the progenitor masses and aligned spins. Our results pave the way for new consistency tests of the ringdown phase, complementary to traditional black hole spectroscopy. + oai:arXiv.org:2512.15877v1 gr-qc astro-ph.HE - astro-ph.SR - hep-th - Fri, 12 Dec 2025 00:00:00 -0500 + hep-ph + Fri, 19 Dec 2025 00:00:00 -0500 cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Nitesh K. Dubey, Sanved Kolekar, Sudipta Sarkar + Romeo Felice Rosato, Sophia Yi, Emanuele Berti, Paolo Pani - Generation of proton beams at switchback boundary-like rotational discontinuities in the solar wind - https://arxiv.org/abs/2512.10406 - arXiv:2512.10406v1 Announce Type: cross -Abstract: Alfv\'enic rotational discontinuities (RDs) are abundant in the inner heliosphere and can be used to model the boundary of switchbacks, i.e. Alfv\'enic magnetic kinks. To investigate the effects of RDs on proton kinetics, we model a pair of switchback-boundary-like RDs with a hybrid Particle-In-Cell (PIC) approach in a 2D system. We find that, at one of the boundary RDs, a significant population of protons remains trapped over long times, creating a secondary beam-like component with temperature anisotropy $T_\perp/T_\|\gtrsim4$ in the proton velocity distribution function that excites ion cyclotron waves within the downstream portion of the transition layer. Further analysis suggests that the static electric field in the vicinity of the RD is the key factor in trapping the protons. This work indicates that switchback boundaries could represent a viable environment for the creation of proton beams in the heliosphere; it also highlights the need to investigate RD sub-structures, especially the embedded current systems of interplanetary RDs. Finally, this paper underscores the importance of high-resolution observations of the solar wind velocity distributions around RDs. - oai:arXiv.org:2512.10406v1 - physics.space-ph - astro-ph.SR - physics.plasm-ph - Fri, 12 Dec 2025 00:00:00 -0500 + Fifty shades of grayness: parameterizations of spectral distortions and applications in cosmology + https://arxiv.org/abs/2512.15893 + arXiv:2512.15893v1 Announce Type: cross +Abstract: Thermal distribution functions can only be of the Fermi-Dirac or Bose-Einstein types, whereas distorted spectra encompass any possible deviations from these shapes. It is fruitful to devise parameterizations of these distortions with only a few parameters which depend on the physical system considered. A method proposed by Stebbins consists in describing a distorted spectrum as a sum of thermalized spectra with a distribution of temperatures, the moments of which are the parameters of interest. After revisiting and extending this approach by working at the level of the number density distribution instead of the standard spectrum, we build another method which consists in describing the distorted spectrum by a polynomial modulating a reference thermalized spectrum. The distortion parameters are then the coefficients of a decomposition on a suitable orthonormal polynomial basis. We advocate that the latter is computationally easier and allows to describe a wide range of distortions. With this formalism, we efficiently describe the standard distortions of the cosmological backgrounds of neutrinos and photons, and we obtain model-independent constraints on nonstandard distortions of these cosmological relics. + oai:arXiv.org:2512.15893v1 + hep-ph + astro-ph.CO + Fri, 19 Dec 2025 00:00:00 -0500 cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Rong Lin, Fabio Bacchini, Jiansen He, Luca Pezzini, Jingyu Peng + Gabriela Barenboim, Julien Froustey, Cyril Pitrou, H\'ector Sanchis - Identification and Characterization of the Topside Bulge of the Venusian Ionosphere - https://arxiv.org/abs/2512.10464 - arXiv:2512.10464v1 Announce Type: cross -Abstract: Venus, in the absence of an intrinsic magnetic field, undergoes a direct interaction between its ionosphere and the solar wind. Previous missions, including Mariner, Venera, and the Pioneer Venus Orbiter (PVO), reported a recurring localized increase in electron density, often termed a "bulge," at altitudes between 160 and 200 km. This study investigates this topside bulge using over 200 dayside electron density profiles derived from the Venus Radio Science experiment (VeRa) onboard the Venus Express (VEX). We employ an automated, gradient-based classification algorithm to provide a quantitative and reproducible method for identifying and categorizing the bulge morphology into three types. Type 1 profiles exhibit a distinct secondary peak above the main V2 layer. Type 2 profiles display a shoulder-like feature near the bulge altitude. Type 3 bulges are not visually apparent but can be identified through residuals obtained after subtracting a Chapman layer fit to the V2 peak. The bulge is detected in over 80\% of the analyzed profiles, with a higher occurrence during periods of low solar activity and at lower solar zenith angles (SZA). Type 1 morphologies are only observed at low latitudes (within $\pm 40^\circ$). The peak altitude of the bulge negatively correlates with SZA, suggesting that thermospheric cooling toward the terminator significantly influences the bulge altitude. The occurrence patterns and morphological characteristics indicate that the bulge is likely influenced by external drivers, such as solar wind interaction, rather than being solely a result of local photochemical processes. - oai:arXiv.org:2512.10464v1 - physics.space-ph - astro-ph.EP - Fri, 12 Dec 2025 00:00:00 -0500 + Introduction to Symbolic Regression in the Physical Sciences + https://arxiv.org/abs/2512.15920 + arXiv:2512.15920v1 Announce Type: cross +Abstract: Symbolic regression (SR) has emerged as a powerful method for uncovering interpretable mathematical relationships from data, offering a novel route to both scientific discovery and efficient empirical modelling. This article introduces the Special Issue on Symbolic Regression for the Physical Sciences, motivated by the Royal Society discussion meeting held in April 2025. The contributions collected here span applications from automated equation discovery and emergent-phenomena modelling to the construction of compact emulators for computationally expensive simulations. + The introductory review outlines the conceptual foundations of SR, contrasts it with conventional regression approaches, and surveys its main use cases in the physical sciences, including the derivation of effective theories, empirical functional forms and surrogate models. We summarise methodological considerations such as search-space design, operator selection, complexity control, feature selection, and integration with modern AI approaches. We also highlight ongoing challenges, including scalability, robustness to noise, overfitting and computational complexity. Finally we emphasise emerging directions, particularly the incorporation of symmetry constraints, asymptotic behaviour and other theoretical information. Taken together, the papers in this Special Issue illustrate the accelerating progress of SR and its growing relevance across the physical sciences. + oai:arXiv.org:2512.15920v1 + cs.LG + astro-ph.IM + cs.NE + physics.comp-ph + physics.data-an + Fri, 19 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - Satyandra M. Sharma, Varun Sheel, Martin P\"atzold + Deaglan J. Bartlett, Harry Desmond, Pedro G. Ferreira, Gabriel Kronberger - A Nonlocal Realization of MOND that Interpolates from Cosmology to Gravitationally Bound Systems - https://arxiv.org/abs/2512.10513 - arXiv:2512.10513v1 Announce Type: cross -Abstract: Nonlocal modifications of gravity derive from corrections to the quantum gravitational stress tensor which grow nonperturbatively strong during primordial inflation and may persist to the current epoch. Phenomenological constructions have been given that realize MOND in gravitationally bound systems and, separately, reproduce all the cosmological phenomena usually ascribed to dark matter, including the cosmic microwave background radiation, baryon acoustic oscillations and linearized structure formation. In this work we exhibit a single model that interpolates between the two regimes. - oai:arXiv.org:2512.10513v1 - gr-qc - astro-ph.CO - hep-th - Fri, 12 Dec 2025 00:00:00 -0500 + Unraveling the anomaly in the production of $^{60}$Fe nucleus in massive stars + https://arxiv.org/abs/2512.16130 + arXiv:2512.16130v1 Announce Type: cross +Abstract: The production of $^{60}$Fe is crucial for nucleosynthesis in massive stars and supernovae. In this work, by using the microscopic EP+IPM (exact pairing plus the independent-particle model) for the nuclear level density (NLD) and extended EP+PDM (exact pairing plus phonon damping model) for the $\gamma$-ray strength function (gSF), we re-evaluate the substantial enhancement of $^{60}$Fe production recently reported in {\it A. Spyrou et al., Nat. Comm. {\bf 15}, 9608 (2024)}, which was attributed to an unexpectedly large Maxwellian-averaged cross section (MACS). Our analysis demonstrates that this enhancement indeed originates from the choice of NLD, which, despite being constrained to reproduce the total NLD and gSF data, lacks a reliable spin dependence, a critical input for Hauser-Feshbach calculations of nuclear reaction rate. In contrast, our predictions yield a significantly lower MACS, calling the claimed enhancement into question. In particular, our approach highlights the microscopic nature of the low-energy enhancement of the gSF, the so-called upbend resonance, which arises from strong particle-particle ($pp$) and hole-hole ($hh$) excitations that emerge only at finite temperature, thereby further reinsisting on the invalidity of the Brink-Axel hypothesis in this low-energy region. Overall, our study reopens the question on the long-standing problem of $^{60}$Fe production in massive stars. + oai:arXiv.org:2512.16130v1 + nucl-th + astro-ph.HE + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - C. Deffayet (Ecole Normale Superieure), R. P. Woodard (U. of Florida) + Samapti Lakshan, Le Tan Phuc, Deepak Pandit, Srijit Bhattacharya, Le Thi Quynh Huong, Nguyen Dinh Dang, Balaram Dey, Nguyen Ngoc Anh, Nguyen Quang Hung + + + Modeling Ultra-High-Energy Cosmic Rays propagation using the input from Configuration Interaction Shell Model + https://arxiv.org/abs/2512.16329 + arXiv:2512.16329v1 Announce Type: cross +Abstract: The dipole response of a nuclear system, characterized by its photon strength function (PSF), is a key ingredient of many applications of nuclear structure, ranging from nuclear reactor design and nuclear waste transmutation to astrophysical models of nucleosynthesis and stellar evolution. While the majority of those applications require the knowledge of PSF of mid-mass and heavy nuclei, there is now renewed interest in $E1$ strength distributions of light nuclei in the framework of the PANDORA project, which aims at an understanding of the mass distribution of ultrahigh-energy cosmic radiation (UHECR).UHECR is of extragalactic origin and its interaction along the travel path is dominated by photoabsorption of cosmic background radiation boosted to the Giant Dipole Resonance (GDR) energy region in the center-of-mass system. Thus, systematic knowledge of the photoabsorption cross sections in light nuclei and of their subsequent particle decay is required. The purpose of this work is to enhance the database of available theoretical evaluations of PSF of light nuclei that are necessary in the studies of UHECR propagation. We employ the Configuration Interaction Shell Model (CI-SM) approach to provide predictions of $E1$ dipole response for $p$ and $sd$-shell nuclei, with mass number $A$ between 7 and 40. Theoretical predictions are compared to available data and to existing predictions from phenomenological and microscopic models. Finally, the impact of using of CI-SM PSF on the predicted propagation of a $^{40}$Ca UHECR source is studied. + oai:arXiv.org:2512.16329v1 + nucl-th + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + O. Le Noan, E. Khan, S. Goriley, K. Sieja - Nonlinear evolution of the ergoregion instability: Turbulence, bursts of radiation, and black hole formation - https://arxiv.org/abs/2512.10526 - arXiv:2512.10526v1 Announce Type: cross -Abstract: Spacetimes with an ergoregion that is not connected to a horizon are linearly unstable. While the linear regime has been studied in a number of settings, little is known about the nonlinear evolution of this ergoregion instability. Here, we investigate this by numerically evolving the unstable growth of a massless vector field in a rapidly spinning boson star in full general relativity. We find that the backreaction of the instability causes the star to become more gravitationally bound, accelerating the growth, and eventually leading to black hole formation. During the nonlinear growth phase, small scale features develop in the unstable mode and emitted radiation as nonlinear gravitational interactions mediate a direct turbulent cascade. The gravitational wave signal exhibits bursts, akin to so-called gravitational wave echoes, with increasing amplitude towards black hole formation. - oai:arXiv.org:2512.10526v1 + Modified light-cylinder and centrifugal acceleration in Schwarzschild geometry + https://arxiv.org/abs/2512.16337 + arXiv:2512.16337v1 Announce Type: cross +Abstract: We examine the motion of an electron constrained to follow a magnetic field line near a primordial sub-stellar mass black hole. Earlier studies treated the problem in flat (Minkowski) spacetime, yielding qualitatively correct results and introducing a light cylinder (LC), a hypothetical surface where the linear velocity of rotation equals the speed of light. However, this picture changes significantly when gravity is included. By analyzing the electron's dynamics in the Schwarzschild metric, we obtain a modified light cylinder (MLC) whose geometry no longer resembles a cylinder. We then determine the maximum energies attainable by the electrons under the limiting effects of inverse Compton scattering, curvature radiation, and synchrotron radiation. + oai:arXiv.org:2512.16337v1 gr-qc astro-ph.HE - hep-ph - hep-th - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - Nils Siemonsen, William E. East + Nikoloz Kurtskhalia, Nikoloz Maltsev, Zaza N. Osmanov - Cosmological and lunar laser ranging constraints on evolving dark energy in a nonminimally coupled curvature-matter gravity model - https://arxiv.org/abs/2512.10530 - arXiv:2512.10530v1 Announce Type: cross -Abstract: We analyze a cosmological solution to the field equations of a modified gravity model where curvature and matter are nonminimally coupled. The current Universe's accelerated expansion is driven by a cosmological constant while the impact of the nonminimal coupling on the expansion history is recast as an effective equation of state for evolving dark energy. The model is analyzed under a tracking solution that follows the minimum of the effective potential for a scalar field that captures the modified theory's effects. We determine the conditions for the existence of this minimum and for the validity of the tracking solution. Cosmological constraints on the parameters of the model are obtained by resorting to recent outcomes of data from the DESI collaboration in combination with the Pantheon+ and Dark Energy Survey supernovae compilations, which give compatible results that point to the presence of a dynamical behavior for dark energy. The gravity model violates the equivalence principle since it gives rise to a fifth force that implies the Earth and Moon fall differently towards the Sun. The cosmological constraints are intersected with limits resulting from a test of the equivalence principle in the Earth-Moon system based on lunar laser ranging data. We find that a variety of model parameters are consistent with both of these constraints, all while producing a dynamical evolution of dark energy with similarities to that found in recent DESI results. - oai:arXiv.org:2512.10530v1 + GWTC-4.0: Searches for Gravitational-Wave Lensing Signatures + https://arxiv.org/abs/2512.16347 + arXiv:2512.16347v1 Announce Type: cross +Abstract: Gravitational waves can be gravitationally lensed by massive objects along their path. Depending on the lens mass and the lens-source geometry, this can lead to the observation of a single distorted signal or multiple repeated events with the same frequency evolution. We present the results for gravitational-wave lensing searches on the data from the first part of the fourth LIGO-Virgo-KAGRA observing run (O4a). We search for strongly lensed events in the newly acquired data by (1) searching for an overall phase shift present in an image formed at a saddle point of the lens potential, (2) looking for pairs of detected candidates with consistent frequency evolution, and (3) identifying sub-threshold counterpart candidates to the detected signals. Beyond strong lensing, we also look for lensing-induced distortions in all detected signals using an isolated point-mass model. We do not find evidence for strongly lensed gravitational-wave signals and use this result to constrain the rate of detectable strongly lensed events and the merger rate density of binary black holes at high redshift. In the search for single distorted lensed signals, we find one outlier: GW231123_135430, for which we report more detailed investigations. While this event is interesting, the associated waveform uncertainties make its interpretation complicated, and future observations of the populations of binary black holes and of gravitational lenses will help determine the probability that this event could be lensed. + oai:arXiv.org:2512.16347v1 gr-qc astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - Riccardo March, Miguel Barroso Varela, Orfeu Bertolami, Giada Bargiacchi, Marco Muccino, Simone Dell'Agnello + The LIGO Scientific Collaboration, The Virgo Collaboration, The KAGRA Collaboration - BinaryGFH-v2: Improved method to search for gravitational waves from sub-solar-mass, ultra-compact binaries using the Generalized Frequency-Hough Transform - https://arxiv.org/abs/2512.10539 - arXiv:2512.10539v1 Announce Type: cross -Abstract: Observing gravitational waves from sub-solar-mass, inspiraling compact binaries would provide almost smoking-gun evidence for primordial black holes. Here, we develop a method to search for ultra-compact binaries with chirp masses ranging from $[10^{-2},10^{-1}]M_\odot$. This mass range represents a previously unexplored gap in gravitational-wave searches for compact binaries: it was thought that the signals would too long for matched-filtering analyses but too short for time-frequency pattern-recognition techniques. Despite this, we show that a pattern-recognition technique, the Generalized frequency-Hough (GFH), can be employed with particular modifications that allow us to handle rapidly spinning-up binaries and to increase the statistical robustness of our method, and call this improved method BinaryGFH-v2. We then design a hypothetical search for binaries in this mass regime, compare the empirical and theoretical sensitivities of this method, and project constraints on formation rate densities and the fraction of dark matter that primordial black holes could compose in both current- and future-generation gravitational-wave detectors. Our results show that our method can be used to search for sub-solar-mass, ultra-compact objects in a mass regime that remains to-date unconstrained with gravitational waves. - oai:arXiv.org:2512.10539v1 + Implementing F (T ) Gravity in Boltzmann Codes: A Framework for Power Spectrum Computation + https://arxiv.org/abs/2512.16404 + arXiv:2512.16404v1 Announce Type: cross +Abstract: This work investigates the nonlinearity of the power-law model of F(T) gravity, highlighting the inability of the Boltzmann solver CLASS to handle nonlinear models. As a workaround, a second-order Taylor expansion is applied to the nonlinear field equations, under the assumption that the extra degree of freedom n, which quantifies deviations from the currently favored cosmological model (\Lambda CDM), remains sufficiently small to preserve the key properties of the \Lambda CDM model. The validity of the Taylor expansion is supported by supernova data indicating n \leq 0.05, for which the power spectrum can be accurately computed within CLASS with a negligible truncation error. + oai:arXiv.org:2512.16404v1 gr-qc - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.CO + Fri, 19 Dec 2025 00:00:00 -0500 cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Andrew L. Miller, Lorenzo Pierini + http://creativecommons.org/licenses/by/4.0/ + Robert Rugg, Shambel Akalu, Amare Abebe - Subtracting compact binary foregrounds utilizing anisotropic statistic for third-generation gravitational-wave detectors - https://arxiv.org/abs/2512.10648 - arXiv:2512.10648v1 Announce Type: cross -Abstract: The astrophysical foreground from compact-binary coalescence signals is expected to be a dominant part of total gravitational wave (GW) energy density in the frequency band of the third-generation detectors. The detection of any other subdominant stochastic GW background (GWB), especially a primordial GWB, will be disturbed by the astrophysical foreground, which needs to be cleaned for further studies of other stochastic GWB. Although previous studies have proposed several cleaning methods, the foreground from subthreshold binary neutron stars (BNS) has been a major obstacle to remove. In this paper, we propose the novel idea to acquire better estimation of the unresolved foreground, by using the information about its anisotropies. We simulate the BNS population and compute its angular power spectrum and shot noise. We find that the shot noise from BNS is too faint to observe after subtracting loud signals due to the limited angular resolution of the third-generation detectors. This justifies the approximation regarding the unresolved foreground as an isotropic component. We also discuss the angular resolution necessary to make our method valid for the foreground subtraction. - oai:arXiv.org:2512.10648v1 + Constraining the nuclear equation of state from terrestrial experiments and neutron star observations using relativistic mean-field models + https://arxiv.org/abs/2512.16429 + arXiv:2512.16429v1 Announce Type: cross +Abstract: We investigate the nuclear equation of state (EoS) for isospin-asymmetric matter using a new set of RMF interactions with the $\sigma$-$\delta$ and $\omega$-$\rho$ mixing, referred to as the OMEG family. These interactions are optimized so as to reproduce both terrestrial nuclear measurements and astrophysical constraints extracted from NICER and GW170817. The $\sigma$-$\delta$ mixing softens the nuclear symmetry energy and pressure around twice the saturation density, which enables relatively small neutron-star radii and tidal deformabilities while keeping the nuclear EoS sufficiently stiff at high densities to support $2M_{\odot}$ neutron stars. We find that the curvature parameter, $K_{\textrm{sym}}$, plays an important role in realizing the soft-to-hard behavior of the nuclear EoS, and the astrophysical data favor small or even negative values of $K_{\textrm{sym}}$. + oai:arXiv.org:2512.16429v1 + nucl-th + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Tsuyoshi Miyatsu, Myung-Ki Cheoun, Kyungsik Kim, Koichi Saito + + + Cosmology with non-linear barotropic Israel-Stewart fluid with causal relaxation time + https://arxiv.org/abs/2512.16502 + arXiv:2512.16502v1 Announce Type: cross +Abstract: We derive an extended expression for the relaxation time of a barotropic Israel-Stewart (IS) fluid using the non-linear causality constraint, and propose a new formulation for modeling causal viscous dissipation in barotropic fluids. With this generalized relaxation time, the non-linear IS equation simplifies to a first-order non-linear expression connecting bulk viscous pressure and energy density, which remains valid in any homogeneous and isotropic spacetime. In the case of spatially flat Friedmann universe, adopting this extended relation in the generalized non-linear IS theory, provides new class of analytical solutions in both, the linear, and the non-linear regimes. We also find that, the resulting effective equation of state in the linear regime naturally reproduces the generalized polytropic form which is often introduced phenomenologically in literature. Resulting dynamical implications are investigated and the constraints necessary for ensuring an acceptable evolutionary behavior for the fluid are determined. A detailed dynamical system analysis of the coupled Einstein-Israel-Stewart (EIS) system is also performed. Finally, we solve the coupled EIS equations numerically, and show that the model can support a transient Hubble slow-roll expansion phase with a smooth exit to a radiation-dominated universe, which is challenging to obtain in standard inflationary models. + oai:arXiv.org:2512.16502v1 gr-qc astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + hep-ph + physics.flu-dyn + Fri, 19 Dec 2025 00:00:00 -0500 cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Soichiro Kuwahara, Atsushi Nishizawa, Lorenzo Valbusa Dall'Armi + http://creativecommons.org/licenses/by/4.0/ + Vishnu A Pai, Titus K Mathew - Efficient pulsar distance measurement with multiple nanohertz gravitational-wave sources - https://arxiv.org/abs/2512.10729 - arXiv:2512.10729v1 Announce Type: cross -Abstract: In recent years, pulsar timing arrays (PTAs) have reported evidence for a nanohertz gravitational-wave (GW) background. As radio telescope sensitivity improves, PTAs are also expected to detect continuous gravitational waves from individual supermassive black hole binaries. Nanohertz GWs generate both Earth and pulsar terms in the timing data, and the time delay between the two terms encodes the pulsar distance. Precise pulsar distance measurements are critical to fully exploiting pulsar-term information, which can improve the measurement precision of GW sources' sky position parameters and thus enhance the GW sky-localization capability. In this work, we propose a new pulsar distance estimation method by using pulsar-term phase information from GWs. We construct two-dimensional distance posteriors for pulsar pairs based on the simulated GW signals and combine them to constrain individual pulsar distances. Compared with the existing one-dimensional method, our approach reduces the impact of source-parameter uncertainties on pulsar distance measurements. Considering four GW sources and a PTA of 20 pulsars with a white-noise level of 20 ns, we find that a significant fraction of pulsars at distances $\lesssim 1.4$ kpc can achieve sub-parsec distance precision over a 15-year observation. - oai:arXiv.org:2512.10729v1 - gr-qc + Chiral magnetic effect amplified baryogenesis at first-order phase transitions + https://arxiv.org/abs/2512.16537 + arXiv:2512.16537v1 Announce Type: cross +Abstract: In this study, we show that, in the background of the primordial magnetic field, the CME effect can significantly amplify the chiral chemical potential sourced by the CP violation near the bubble walls during the first-order electroweak phase transition. This effect can lift the generated baryon asymmetry by several orders, and make it possible to explain the baryon asymmetry of the Universe with a CPV in the fermion sector far beyond the limitation of the electron dipole moment. + oai:arXiv.org:2512.16537v1 + hep-ph astro-ph.CO + hep-th + Fri, 19 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Hui Liu, Ligong Bian + + + Photon Accelerator in Magnetized Plasma + https://arxiv.org/abs/2512.16630 + arXiv:2512.16630v1 Announce Type: cross +Abstract: Strong magnetic fields and plasmas are intrinsically linked in both terrestrial laboratory experiments and in space phenomena. One of the most profound consequences of that is the change in relationship between the frequency and the wave number of electromagnetic waves propagating in plasma in the presence of such magnetic fields when compared to the case without these fields. Furthermore, magnetic fields alter electromagnetic wave interaction with relativistic plasma waves, resulting in different outcomes for particle and radiation generation. For a relativistic plasma wave-based photon acceleration this leads to an increased frequency gain, and, thus, potentially to higher efficiency. The influence of a magnetic field leads to quantitative and qualitative change in the properties of photon acceleration, amplifying the increase in the electromagnetic wave frequency. + oai:arXiv.org:2512.16630v1 + physics.plasm-ph astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Sergei Bulanov, Stepan Bulanov, Timur Esirkepov, Gianluca Gregori, Gabriele Grittani, Brandon Russell, Alec Thomas, Petr Valenta + + + On Non-Minimal Couplings to Gravity and Axion Isocurvature Bounds + https://arxiv.org/abs/2512.16754 + arXiv:2512.16754v1 Announce Type: cross +Abstract: For axions present during inflation, it has been shown that a non-minimal coupling $\xi_\sigma$ of the inflaton to gravity worsens isocurvature bounds, while a non-minimal coupling $\xi_\rho$ of the radial Peccei-Quinn field can alleviate them. We analyze the simultaneous presence of both couplings and determine when one effect dominates the other, in both the metric and Palatini formulations of gravity. The two tendencies interpolate smoothly, but introducing a non-minimal inflaton coupling reduces the viable interval of $\xi_\rho$ in which isocurvature bounds can be alleviated while avoiding backreaction on the inflationary dynamics. We illustrate our findings in Palatini Higgs inflation and Starobinsky inflation. + oai:arXiv.org:2512.16754v1 hep-ph - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.CO + gr-qc + hep-th + Fri, 19 Dec 2025 00:00:00 -0500 cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Si-Ren Xiao, Ji-Yu Song, Yue Shao, Ling-Feng Wang, Jing-Fei Zhang, Xin Zhang + Claire Rigouzzo, Sebastian Zell - Exploring New Propagation Scales With Galactic Neutrinos - https://arxiv.org/abs/2512.10744 - arXiv:2512.10744v1 Announce Type: cross -Abstract: The recent observation of high-energy Galactic neutrinos by IceCube allows for searches of new physics affecting neutrino propagation on scales of $O(10^9-10^{15})\,\mathrm{km/GeV}$ in distance over energy. We assess the sensitivity of upcoming measurements of Galactic neutrinos by IceCube and KM3NeT to such new phenomena. We focus on two scenarios: quasi-Dirac neutrinos and neutrino decays. In the quasi-Dirac scenario, we find that joint measurements by IceCube and KM3NeT are sensitive to the mass-squared differences $\delta m^2 \in \left(10^{-13.5}~\mathrm{eV^2}, 10^{-11.9}~\mathrm{eV^2}\right)$ at the $90\%$ confidence level. For neutrino decays, the same measurements are sensitive to mass over lifetime ratios $m / \tau > 10^{-12.3}~\mathrm{eV^2}$ at the same significance. Our results demonstrate that measurements of Galactic neutrinos by a global network of neutrino telescopes can probe signatures of neutrino mass models. - oai:arXiv.org:2512.10744v1 + Impact of Supercooling on Direct Searches for Dark Matter and Gravitational Wave Backgrounds + https://arxiv.org/abs/2512.16809 + arXiv:2512.16809v1 Announce Type: cross +Abstract: An interesting feature of a cosmological phase transition can be a stage of exponential expansion (supercooling). The modified expansion history and the entropy injection at reheating, can affect the final energy fraction of dark matter. In this paper, we revisit the calculation of the freeze-out and freeze-in dynamics, showing additional effects on top of the standard dilution factor if the dark matter production is completed during the supercooling stage. We show for the first time how these effects can be particularly interesting for direct detection, as the parameter space for WIMP-like candidates shifts from excluded to allowed regions, and freeze-in candidates get closer to experimental reach. A phenomenological motivation to consider supercooling is the associated gravitational wave background. The implications of a finite-duration reheating stage, when the equation of state is close to matter-domination, are a peculiar low-frequency spectrum, and its shift to lower frequencies. These effects are a complementary test of the dynamics that we study for dark matter production, and remarkably can link direct detection of dark matter and gravitational wave astronomy. + oai:arXiv.org:2512.16809v1 hep-ph - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.CO + hep-th + Fri, 19 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - Miller MacDonald, Kiara Carloni, Carlos A. Arg\"uelles, Ivan Mart\'inez-Soler, Rafael Alves Batista + Davide Racco, Alfredo Stanzione - Measuring the neutron star equation of state from EMRIs in dark matter environments with LISA - https://arxiv.org/abs/2512.10855 - arXiv:2512.10855v1 Announce Type: cross -Abstract: Gravitational-wave observations of extreme mass-ratio inspirals (EMRIs) in vacuum are largely insensitive to the internal structure of the small compact companion. We show that this conclusion can change when the central black hole is surrounded by a dense dark matter environment. We compute, for the first time, the relativistic dynamical-friction force on a neutron star moving through a collisionless medium and its impact on the evolution of EMRIs embedded in dense dark matter spikes. We then perform a Bayesian parameter-estimation analysis of simulated LISA observations to assess the measurability of both spike properties and the companion's internal structure. We find that, in our fiducial dark matter spike models, EMRIs with signal-to-noise ratio (SNR) $\gtrsim 20$ already allow us to distinguish neutron star from black hole companions, while events with SNR $\gtrsim 400$ make it possible to discriminate between different neutron star equations of state. - oai:arXiv.org:2512.10855v1 + Exponential plateaus and inflation in metric-affine gravity + https://arxiv.org/abs/2512.16815 + arXiv:2512.16815v1 Announce Type: cross +Abstract: We propose a new mechanism for inflationary model building in the framework of metric-affine gravity. Such a mechanism involves an inflaton non-minimally coupled with the Holst invariant. If the non-minimal coupling function has a zero point and it is very steep at that same point, then the canonically normalized inflaton potential always features an exponential plateau, regardless of the shape of the original inflaton potential. The inflationary predictions in such a region are equivalent to the ones of Starobinsky inflation. + oai:arXiv.org:2512.16815v1 gr-qc astro-ph.CO - astro-ph.HE hep-ph - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Theophanes K. Karydas, Gianfranco Bertone + Antonio Racioppi - Heterogeneous Cosmological Phase Transitions: Seeded by Domain Walls and Junctions - https://arxiv.org/abs/2512.10917 - arXiv:2512.10917v1 Announce Type: cross -Abstract: Heterogeneous nucleation is central to many familiar first-order phase transitions such as the freezing of water and the solidification of metals, and it can also play a crucial role in cosmology. We examine nucleation seeded by preexisting domain walls and demonstrate its strong impact on the dynamics of cosmological phase transitions. The bubble solutions take the form of spherical caps, and the contact angle is fixed by the ratio of the domain-wall tension to the bubble-wall tension. A larger domain-wall tension, or equivalently a smaller contact angle, reduces the wall-seeded bubble volume and lowers the critical nucleation action. For theories with $\mathbb{Z}_{n\geq 3}$ symmetry, domain-wall junctions naturally appear and we find that they seed nucleation even more efficiently than the walls themselves. Using a two-scalar-field model as an illustration, we compute nucleation temperatures for both homogeneous and heterogeneous channels and show that junction-seeded nucleation occurs at a higher temperature and is the dominant mechanism that completes the first-order cosmological phase transition. - oai:arXiv.org:2512.10917v1 + Delayed Scaling of Multi-Type Cosmic F- and D-strings in VOS Models + https://arxiv.org/abs/2512.16821 + arXiv:2512.16821v1 Announce Type: cross +Abstract: We investigate the velocity-dependent one-scale (VOS) model to the case of one cosmic F-string and two D-strings as color flux tubes in pure Spin($4N$) gauge theory. We analytically calculate the scaling string density as a function of the reconnection probabilities, and confirm our results with numerical calculations. We also determine the timescale at which the string density reaches the scaling regime, and find that for certain values of the reconnection probability, the scaling time can become extremely large, by many orders of magnitude. This leads to a characteristic suppression signature of the gravitational-wave signal at high frequencies, which may become observable in the frequency range of future interferometric gravitational-wave observations. + oai:arXiv.org:2512.16821v1 hep-ph astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + gr-qc + hep-th + Fri, 19 Dec 2025 00:00:00 -0500 cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yang Bai, Yifu Xu, Yiming Yang + Kazuto Nakamura, Masaki Yamada - Comprehensive survey of hybrid equations of state in neutron star mergers and constraints on the hadron-quark phase transition - https://arxiv.org/abs/2406.14669 - arXiv:2406.14669v2 Announce Type: replace -Abstract: We perform an extensive study of equation of state (EoS) models featuring a phase transition from hadronic to deconfined quark matter in neutron star merger simulations. We employ three different hadronic EoSs, a constant speed of sound parameterization for the quark phase and a Maxwell construction to generate a large sample of hybrid EoS models. We systematically vary the onset density and density jump of the phase transition as well as the quark matter stiffness and simulate binary neutron star mergers to infer how the properties of the phase transition affect the gravitational-wave signal. In total we simulate mergers with 245 different hybrid EoS models. In particular, we explore in which scenarios a phase transition would be detectable by a characteristically increased postmerger gravitational-wave frequency compared to an estimate from the inspiral signal assuming a purely hadronic EoS. We find that the density jump at the transition (latent heat) has the largest impact on the gravitational-wave frequencies, while the influence of the stiffness of quark matter is smaller. We quantify which range of phase transition properties would be compatible with a certain magnitude or absence of the gravitational-wave postmerger frequency shift. By means of these dependencies, a future detection will thus directly yield constraints on the allowed features of the hadron-quark phase transition. - oai:arXiv.org:2406.14669v2 - astro-ph.HE + Multiple Axions in Laboratory Experiments + https://arxiv.org/abs/2512.16837 + arXiv:2512.16837v1 Announce Type: cross +Abstract: Axions and axion-like particles generically appear in extensions of the Standard Model. While many searches assume only a single axion species, there may exist a whole spectrum of multiple such fields. We develop general formulas for axion-photon oscillations in the presence of multiple axions and analyze the implications for experimental searches, including light-shining-through-a-wall experiments, helioscopes and haloscopes. We demonstrate that axion multiplicity can qualitatively alter observational signatures, particularly through coherence and interference effects. Multiple axions can not only enhance signals compared to single axion scenarios, but also suppress them. We show that variations of experimental parameters and searches allow identifying contributions of multiple axions and obtaining information about their properties. + oai:arXiv.org:2512.16837v1 hep-ph - Fri, 12 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Sebastian Blacker, Andreas Bauswein - - - Bringing together African & European research communities with an inclusive astronomy conference - https://arxiv.org/abs/2411.12834 - arXiv:2411.12834v2 Announce Type: replace -Abstract: We report on an international scientific conference, where we brought together African and European academic astronomers. This aimed to bridge the gap between those in position of privilege, with ease of access to international events (i.e., the typical experience of academics in Western institutions), with those historically excluded (affecting the majority of African scientists/institutions). We describe how we designed the conference around cutting-edge research problems, but with a parallel focus on building networking and professional relationships. Significant effort went into: (1) ensuring a diversity of participants; (2) practically and financially supporting those who may never have attended an international conference and; (3) creating an inclusive and supportive environment through a careful programme of activities, both before and during the event. Maintaining scientific integrity was a core commitment throughout. We summarise successes, challenges and lessons learnt from organising this conference. We also present feedback obtained from participants immediately after the conference, and a discussion of some longer-term impacts, which we identified around 1 year later. We found an overall achievement of our objectives, and multiple longer-term benefits. With this report we provide some key recommendations for groups, from any research field, who may wish to lead similar initiatives. - oai:arXiv.org:2411.12834v2 - astro-ph.IM - astro-ph.GA - physics.ed-ph - physics.soc-ph - Fri, 12 Dec 2025 00:00:00 -0500 - replace + astro-ph.CO + hep-ex + Fri, 19 Dec 2025 00:00:00 -0500 + cross http://creativecommons.org/licenses/by/4.0/ - Chris M. Harrison (Newcastle University), Leah Morabito (Durham University), Ann Njeri (Newcastle University, on behalf of the Organising Committees) + Arturo de Giorgi, Joerg Jaeckel, Sebastian Monath, Volodymyr Takhistov - Tidally Delayed Spin-Down of Very Low Mass Stars - https://arxiv.org/abs/2411.17916 - arXiv:2411.17916v3 Announce Type: replace -Abstract: Very low-mass main-sequence stars reveal some curious trends in observed rotation period distributions that require abating the spin-down that standard rotational evolution models would otherwise imply. By dynamically coupling magnetically mediated spin-down to tidally induced spin-up from close orbiting substellar companions, we show that tides from sub-stellar companions may explain these trends. In particular, brown dwarf companions can delay the spin-down and explain the dearth of field, late-type M dwarfs with intermediate rotation periods. We find that tidal forces also strongly influence stellar X-ray activity evolution, so that methods of gyrochronological aging must be generalized for stars with even sub-stellar companions. We also discuss how the theoretical predictions of the spin evolution model can be used with future data to constrain the population distribution of companion orbital separations. - oai:arXiv.org:2411.17916v3 + Science Requirement Document (SRD) for the European Solar Telescope (EST) (3rd Edition, December 2025) + https://arxiv.org/abs/1912.08650 + arXiv:1912.08650v2 Announce Type: replace +Abstract: The European Strategy Forum on Research Infrastructures (ESFRI) included the European Solar Telescope (EST) as an ESFRI Project in its 2016 Roadmap and confirmed this status in 2021. During the Preparatory Phase (2017 to 2022), the EST Science Advisory Group (SAG) was established in 2017. Its first task was to revise the Science Requirements Document (SRD), originally formulated in 2011. This second edition of the SRD was published in December 2019 (Schlichenmaier et al. 2019, 2019arXiv191208650S). + Since 2019, the EST Project Office has advanced the telescope design and developed the Science Instrumentation Suite (SIS). All telescope subsystems and the SIS have now passed their Design Reviews. Aligned with the discussions and resolutions of the SAG, the SIS comprises three categories of first-generation instruments: (1) Tunable Imaging Spectropolarimeters coupled with Fixed Band Imagers (TIS/FBIs), employing large-aperture Fabry-P\'erot etalons; (2) Integral Field Spectropolarimeters based on microlens arrays (IFS-M); (3) The near-infrared spectropolarimeter EMBER (spectropolariMeter Based on slicEr-mirrors for the near-infraRed), using image-slicing technology. This configuration enables simultaneous observations of the same two-dimensional solar region across a broad wavelength range (380-2200 nm), giving EST a uniquely powerful multi-wavelength observing capability. + This has made it necessary to revise the Observing Programmes so that they accurately reflect the capabilities of the SIS and ensure that all science objectives can be met. This third edition of the EST SRD integrates the outcomes of numerous SAG meetings held between 2020 and 2025 and incorporates all design developments up to 2025. It updates the Observing Programmes accordingly and assesses their alignment with the scientific objectives defined by the SAG. + oai:arXiv.org:1912.08650v2 astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.IM + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Ketevan Kotorashvili, Eric G. Blackman + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Rolf Schlichenmaier (Leibniz-Institut f\"ur Sonnenphysik), Luis R. Bellot Rubio (Instituto de Astrofisica de Andalucia), Manuel Collados Vera (Instituto de Astrofisica de Canarias, Departamento de Astrofisica, Universidad de La Laguna), Robertus Erdelyi (SP2RC, University of Sheffield, Dept of Astronomy, E\"otv\"os University, Gyula Bay Zoltan Solar Observatory), Alex Feller (Max-Planck-Institut f\"ur Sonnensystemforschung), Lyndsay Fletcher (SUPA School of Physics and Astronomy, University of Glasgow, Rosseland Centre for Solar Physics, University of Oslo), Jan Jur\v{c}\'ak (Astronomical Institute of the Czech Academy of Sciences, Ondrejov), Elena Khomenko (Instituto de Astrofisica de Canarias), Jorrit Leenaarts (Institute for Solar Physics, Department of Astronomy, Stockholm University), Sara Matthews (UCL Mullard Space Science Laboratory), Luca Belluzzi (Istituto Ricerche Solari Locarno, Leibniz-Institut f\"ur Sonnenphysik), Mats Carlsson (Rosseland Centre for Solar Physics, University of Oslo, Institute of Theoretical Astrophysics, University of Oslo), Sanja Danilovic (Institute for Solar Physics, Department of Astronomy, Stockholm University), Peter G\"om\"ory (Astronomical Institute of the Slovak Academy of Sciences, Tatranska Lomnica), Christoph Kuckein (Instituto de Astrofisica de Canarias), Rafail Manso Sainz (Third Institute of Physics, University of G\"ottingen), Mari\'an Mart\'inez Gonz\'alez (Instituto de Astrofisica de Canarias), Mihalis Mathioudakis (Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast), Ada Ortiz (Expert Analytics AS, Oslo, European Solar Telescope Canarian Foundation), Tino L. Riethm\"uller (Max-Planck-Institut f\"ur Sonnensystemforschung), Luc Rouppe van der Voort (Rosseland Centre for Solar Physics, University of Oslo, Institute of Theoretical Astrophysics, University of Oslo), Paolo J. A. Simoes (Centro de Radio Astronomia e Astrofisica Mackenzie, Sao Paulo), Javier Trujillo Bueno (Instituto de Astrofisica de Canarias, Consejo Superior de Investigaciones Cientificas), Dominik Utz (IGAM Institute of Physics, Karl-Franzens University Graz), Francesca Zuccarello (Dipartimento di Fisica e Astronomia, University of Catania), Jaime de la Cruz Rodriguez (Institute for Solar Physics, Department of Astronomy, Stockholm University), Luca Giovanelli (Department of Physics, University of Rome Tor Vergata), Shahin Jafarzadeh (Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast), David B. Jess (Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast), Ivan Milic (Leibniz-Institut f\"ur Sonnenphysik), Chris Nelson (European Space Agency), Michiel van Noort (Max-Planck-Institut f\"ur Sonnensystemforschung), Claudia Ruiz de Galarreta (Instituto de Astrofisica de Canarias), Franziska Zeuner (Istituto Ricerche Solari Locarno) - Probing Spin-Orbit Resonances with the Binary Black Hole Population - https://arxiv.org/abs/2502.04278 - arXiv:2502.04278v2 Announce Type: replace -Abstract: Measurements of the binary black hole spin distribution from the growing catalog of gravitational-wave observations can help elucidate the astrophysical processes shaping the formation and evolution of these systems. Spin-orbit resonances are one process of interest, in which the component spin vectors and the orbital angular momentum align into a common plane and jointly precess about the total angular momentum of the system. These resonances, which occur preferentially in systems formed via isolated binary evolution with strong tidal effects, lead to excesses in the distribution of the azimuthal angle between the projections of the component spin vectors onto the orbital plane at $\phi_{12}=0,\pm\pi$. In this work, we conduct the first hierarchical analysis modeling the population-level distribution of $\phi_{12}$ simultaneously with the other mass and spin parameters for simulated binary black hole populations to determine whether spin-orbit resonances can be reliably constrained. While we are unlikely to find definitive evidence for spin-orbit resonances with a population of the size expected by the end of the ongoing LIGO-Virgo-KAGRA fourth observing run, we correctly recover the various $\phi_{12}$ distributions we simulate within uncertainties. We find that we can place meaningful constraints on the relative excesses at $\phi_{12}=0,\pm\pi$, which encodes information about binary mass transfer. We can also distinguish between fully isotropic spin angle distributions and those with features in the spin azimuth and tilt distributions. Thus, we show that population-level measurements of the $\phi_{12}$ distribution offer a reliable, novel way to probe binary formation channels, dynamics, and mass transfer with gravitational-wave observations. - oai:arXiv.org:2502.04278v2 + Binary Black Hole Mergers: Spin and mass ratio effects on gravitational waveforms + https://arxiv.org/abs/2304.09396 + arXiv:2304.09396v2 Announce Type: replace +Abstract: We present a comprehensive parameter-space study of binary black hole (BBH) mergers using the SEOBNRv4\_opt waveform model. Our analysis spans $\sim 10^6$ simulated waveforms across a broad range of mass ratios \( q = \frac{m_1}{m_2} \in [1.0, 2.0] \) and aligned spin configurations. We investigate the influence of these parameters on remnant properties, including final spin ($\chi_f$), fractional mass loss ($M_{\mathrm{FL}}$), and peak gravitational-wave strain ($h_{\max}$). By systematically analyzing the trends across four distinct spin alignments (PP, PN, BP, BN), we identify non-monotonic behaviors and turning points in $M_{\mathrm{FL}}$ and $\chi_f$ as functions of $q$, highlighting subtle dynamical effects that are not explicitly emphasized in commonly used remnant fitting formulae. While confirming known correlations from numerical relativity, our results offer new insights into parameter interactions and waveform morphology, with implications for BBH population studies and remnant characterization. Across all configurations studied, the fractional mass loss due to gravitational-wave emission ranges between 2\% and 9.5\%, depending on the mass ratio and spin alignment. This work may also aid in understanding the spin and mass distributions of the more massive black holes formed post-merger, thereby contributing to future remnant-based astrophysical inference. + oai:arXiv.org:2304.09396v2 astro-ph.HE + astro-ph.SR gr-qc - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Sylvia Biscoveanu + \.Ismail \"Ozbak{\i}r, Kadri Yakut - Retrograde predominance of small saturnian moons reiterates a recent retrograde collisional disruption - https://arxiv.org/abs/2503.07081 - arXiv:2503.07081v2 Announce Type: replace -Abstract: We report the discovery and careful orbital determination of 64 new irregular moons of Saturn found in images taken using the Canada-France-Hawaii Telescope from 2019-2021, bringing the total number of saturnian irregulars to 122. By more than doubling the sample of saturnian irregular moon orbits, including pushing to smaller sizes, we can now see finer detail in their orbital distribution. We note the emergence of potential subgroups associated with each of Siarnaq and Kiviuq within the Inuit group. - We find that in the inclination range 157-172 degrees the ratio of smaller moons (diameters less than 4 km) to larger moons (diameters greater than 4 km) is significantly larger than that of any other inclination range in the retrogrades. We denote this subset of the Norse group as the Mundilfari subgroup after its largest member. The incredibly steep slope of the Mundilfari subgroup's size distribution, with a differential power law index of q = 6, strengthens the hypothesis in Ashton et al. (2021) that this subgroup was created by a recent catastrophic collision, $<10^8$ yr ago. - oai:arXiv.org:2503.07081v2 - astro-ph.EP - Fri, 12 Dec 2025 00:00:00 -0500 + Radiation-driven dusty outflows from early galaxies + https://arxiv.org/abs/2412.07598 + arXiv:2412.07598v4 Announce Type: replace +Abstract: The James Webb Space Telescope (JWST) has discovered an overabundance of UV-bright ($M_{\rm UV} \lesssim -20$), massive galaxies at $z \gtrsim 10$ in comparison to pre-JWST theoretical predictions. Among the proposed interpretations, such excess has been explained by negligible dust attenuation conditions following radiation-driven outflows launched by young stars when a galaxy goes through a super-Eddington phase. Dust opacity decreases the classical Eddington luminosity by a (boost) factor $A$, thus favoring the driving of outflows by stellar radiation in compact, initially dusty galaxies. Here, we compute $A$ as a function of the galaxy stellar mass, gas fraction, galaxy size, and metallicity (a total of 8 parameters). We find that the main dependence is on metallicity and, for the fiducial model, $A \sim 1800(Z/Z_\odot)/(1+N_{\rm H}/10^{23.5}\, {\rm cm^2})$. We apply such results to 20 spectroscopically confirmed galaxies at $z \gtrsim 10$ and evaluate their modified Eddington ratio. We predict that three galaxies are in the outflow phase. Their outflows have relatively low velocities ($60 -100 \,{\rm km\ s^{-1}}$), implying that they are unlikely to escape from the system. For the remaining 17 galaxies that are not currently in the outflow phase, we calculate the past evolution of the modified Eddington ratio from their star formation history. We find that 15 of them experienced an outflow phase prior to observation during which they effectively displaced their dust to larger radii. Thus, dusty outflows driven by stellar radiation appear to contribute to the observed bright UV galaxies at $z > 10$. + oai:arXiv.org:2412.07598v4 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by-nc-nd/4.0/ - 10.3847/PSJ/ae1d62 - Edward Ashton et al (2025) Planet. Sci. J. 6 283 - Edward Ashton, Brett Gladman, Mike Alexandersen, Jean-Marc Petit + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1093/mnras/staf2028 + Mon Not R Astron Soc (2025) 4390-4402 + Yurina Nakazato, Andrea Ferrara - Euclid Quick Data Release (Q1): VIS processing and data products - https://arxiv.org/abs/2503.15303 - arXiv:2503.15303v2 Announce Type: replace -Abstract: This paper describes the VIS Processing Function (VIS PF) of the Euclid ground segment pipeline, which processes and calibrates raw data from the VIS camera. We present the algorithms used in each processing element, along with a description of the on-orbit performance of VIS PF, based on Performance Verification (PV) and Q1 data. We demonstrate that the principal performance metrics (image quality, astrometric accuracy, photometric calibration) are within pre-launch specifications. The image-to-image photometric scatter is less than $0.8\%$, and absolute astrometric accuracy compared to Gaia is $5$ mas Image quality is stable over all Q1 images with a full width at half maximum (FWHM) of $0.\!^{\prime\prime}16$. The stacked images (combining four nominal and two short exposures) reach $I_\mathrm{E} = 25.6$ ($10\sigma$, measured as the variance of $1.\!^{\prime\prime}3$ diameter apertures). We also describe quality control metrics provided with each image, and an appendix provides a detailed description of the provided data products. The excellent quality of these images demonstrates the immense potential of Euclid VIS data for weak lensing. VIS data, covering most of the extragalactic sky, will provide a lasting high-resolution atlas of the Universe. - oai:arXiv.org:2503.15303v2 - astro-ph.IM + Benchmarking field-level cosmological inference from galaxy redshift surveys + https://arxiv.org/abs/2504.20130 + arXiv:2504.20130v2 Announce Type: replace +Abstract: Field-level inference has emerged as a promising framework to fully harness the cosmological information encoded in next-generation galaxy surveys. It involves performing Bayesian inference to jointly estimate the cosmological parameters and the initial conditions of the cosmic field, directly from the observed galaxy density field. Yet, the scalability and efficiency of sampling algorithms for field-level inference of large-scale surveys remain unclear. To address this, we introduce a standardized benchmark using a fast and differentiable simulator for the galaxy density field based on $\texttt{JaxPM}$. We evaluate a range of sampling methods, including standard Hamiltonian Monte Carlo (HMC), No-U-Turn Sampler (NUTS) without and within a Gibbs scheme, and both adjusted and unadjusted microcanonical samplers (MAMS and MCLMC). These methods are compared based on their efficiency, in particular the number of model evaluations required per effective posterior sample. Our findings emphasize the importance of carefully preconditioning latent variables and demonstrate the significant advantage of (unadjusted) MCLMC for scaling to $\geq 10^6$-dimensional problems. We find that MCLMC outperforms adjusted samplers by over an order-of-magnitude, with a mild scaling with the dimension of our inference problem. This benchmark, along with the associated publicly available code, is intended to serve as a basis for the evaluation of future field-level sampling strategies. The code is readily open-sourced at https://github.com/hsimonfroy/benchmark-field-level + oai:arXiv.org:2504.20130v2 astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.IM + stat.CO + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Euclid Collaboration, H. J. McCracken, K. Benson, C. Dolding, T. Flanet, C. Grenet, O. Herent, P. Hudelot, C. Laigle, G. Leroy, P. Liebing, R. Massey, S. Mottet, R. Nakajima, H. N. Nguyen-Kim, J. W. Nightingale, J. Skottfelt, L. C. Smith, F. Soldano, E. Vilenius, M. Wander, M. von Wietersheim-Kramsta, M. Akhlaghi, H. Aussel, S. Awan, R. Azzollini, A. Basset, G. P. Candini, P. Casenove, M. Cropper, H. Hoekstra, H. Israel, A. Khalil, K. Kuijken, Y. Mellier, L. Miller, S. -M. Niemi, M. J. Page, K. Paterson, M. Schirmer, N. A. Walton, A. Zacchei, J. P. L. G. Barrios, T. Erben, R. Hayes, J. A. Kegerreis, D. J. Lagattuta, A. Lan\c{c}on, N. Aghanim, B. Altieri, A. Amara, S. Andreon, P. N. Appleton, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, A. N. Belikov, R. Bender, F. Bernardeau, A. Biviano, A. Bonchi, E. Branchini, M. Brescia, J. Brinchmann, S. Camera, G. Ca\~nas-Herrera, V. Capobianco, C. Carbone, J. Carretero, S. Casas, F. J. Castander, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, A. Da Silva, R. da Silva, H. Degaudenzi, G. De Lucia, A. M. Di Giorgio, J. Dinis, H. Dole, F. Dubath, X. Dupac, S. Dusini, A. Ealet, S. Escoffier, M. Fabricius, M. Farina, R. Farinelli, S. Ferriol, F. Finelli, P. Fosalba, S. Fotopoulou, N. Fourmanoit, M. Frailis, E. Franceschi, S. Galeotta, K. George, W. Gillard, B. Gillis, C. Giocoli, P. G\'omez-Alvarez, J. Gracia-Carpio, B. R. Granett, A. Grazian, F. Grupp, L. Guzzo, M. Hailey, S. V. H. Haugan, J. Hoar, W. Holmes, F. Hormuth, A. Hornstrup, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keih\"anen, S. Kermiche, A. Kiessling, M. Kilbinger, B. Kubik, M. K\"ummel, M. Kunz, H. Kurki-Suonio, Q. Le Boulc'h, A. M. C. Le Brun, D. Le Mignant, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, S. Marcin, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, D. C. Masters, S. Maurogordato, E. Medinaceli, S. Mei, M. Melchior, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, C. Neissner, R. C. Nichol, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, G. D. Racca, F. Raison, R. Rebolo, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, E. Rossetti, B. Rusholme, R. Saglia, Z. Sakr, A. G. S\'anchez, D. Sapone, B. Sartoris, J. A. Schewtschenko, P. Schneider, T. Schrabback, A. Secroun, G. Seidel, M. Seiffert, S. Serrano, P. Simon, C. Sirignano, G. Sirri, A. Spurio Mancini, L. Stanco, J. Steinwagner, P. Tallada-Cresp\'i, D. Tavagnacco, A. N. Taylor, H. I. Teplitz, I. Tereno, N. Tessore, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, E. A. Valentijn, L. Valenziano, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, F. M. Zerbi, I. A. Zinchenko, E. Zucca, V. Allevato, M. Ballardini, M. Bolzonella, E. Bozzo, C. Burigana, R. Cabanac, M. Calabrese, A. Cappi, D. Di Ferdinando, J. A. Escartin Vigo, G. Fabbian, L. Gabarra, M. Huertas-Company, J. Mart\'in-Fleitas, S. Matthew, N. Mauri, R. B. Metcalf, A. Pezzotta, M. P\"ontinen, C. Porciani, I. Risso, V. Scottez, M. Sereno, M. Tenti, M. Viel, M. Wiesmann, Y. Akrami, I. T. Andika, S. Anselmi, M. Archidiacono, F. Atrio-Barandela, C. Benoist, P. Bergamini, D. Bertacca, M. Bethermin, L. Bisigello, A. Blanchard, L. Blot, S. Borgani, A. S. Borlaff, M. L. Brown, S. Bruton, A. Calabro, B. Camacho Quevedo, F. Caro, C. S. Carvalho, T. Castro, F. Cogato, S. Conseil, A. R. Cooray, O. Cucciati, S. Davini, F. De Paolis, G. Desprez, A. D\'iaz-S\'anchez, J. J. Diaz, S. Di Domizio, J. M. Diego, P. -A. Duc, A. Enia, Y. Fang, A. M. N. Ferguson, A. G. Ferrari, A. Finoguenov, A. Fontana, A. Franco, K. Ganga, J. Garc\'ia-Bellido, T. Gasparetto, V. Gautard, E. Gaztanaga, F. Giacomini, F. Gianotti, A. H. Gonzalez, G. Gozaliasl, A. Gregorio, M. Guidi, C. M. Gutierrez, A. Hall, W. G. Hartley, C. Hern\'andez-Monteagudo, H. Hildebrandt, J. Hjorth, J. J. E. Kajava, Y. Kang, V. Kansal, D. Karagiannis, K. Kiiveri, C. C. Kirkpatrick, S. Kruk, J. Le Graet, L. Legrand, M. Lembo, F. Lepori, G. F. Lesci, J. Lesgourgues, L. Leuzzi, T. I. Liaudat, S. J. Liu, A. Loureiro, J. Macias-Perez, G. Maggio, M. Magliocchetti, F. Mannucci, R. Maoli, C. J. A. P. Martins, L. Maurin, C. J. R. McPartland, M. Miluzio, P. Monaco, A. Montoro, C. Moretti, G. Morgante, C. Murray, S. Nadathur, K. Naidoo, A. Navarro-Alsina, S. Nesseris, F. Passalacqua, L. Patrizii, A. Pisani, D. Potter, S. Quai, M. Radovich, P. Reimberg, P. -F. Rocci, G. Rodighiero, R. P. Rollins, S. Sacquegna, M. Sahl\'en, D. B. Sanders, E. Sarpa, C. Scarlata, A. Schneider, M. Schultheis, D. Sciotti, E. Sellentin, F. Shankar, A. Silvestri, K. Tanidis, C. Tao, G. Testera, M. Tewes, R. Teyssier, S. Tosi, A. Troja, M. Tucci, C. Valieri, A. Venhola, D. Vergani, G. Verza, P. Vielzeuf, J. R. Weaver, D. Scott + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1088/1475-7516/2025/12/039 + JCAP12(2025)039 + Hugo Simon, Fran\c{c}ois Lanusse, Arnaud de Mattia - The dark side of the universe may be more harmonic than we thought - https://arxiv.org/abs/2504.00536 - arXiv:2504.00536v4 Announce Type: replace -Abstract: The standard paradigm of cosmology assumes two distinct dark components, namely dark matter and dark energy. However, the necessity of splitting the dark-side world into two sectors has not been experimentally or theoretically proven. Unified dark fluid models provide an alternative in which a single fluid accounts for both phenomena. It is shown in Wang et al. 2024 that a PAge-like unified dark fluid (PUDF) can explain both the cosmic microwave background (CMB) and late-universe data, with the fitting quality not much worse than the standard Lambda cold dark matter ($\Lambda$CDM) model. Using the Planck 2018 CMB, baryon acoustic oscillations measurement from the dark energy spectroscopic instrument (DESI) data release 2, dark energy survey 5-year supernova data, and cosmic-chronometer data, we update the constraints on PUDF and clarify its physical implications. We show that PUDF can reproduce the primary CMB anisotropies, the background expansion history, and linear growth that are very close to the $\Lambda$CDM prediction. Nevertheless, the combined datasets still favor $\Lambda$CDM, largely due to the significant tension between CMB and DESI + SNe data, which exceeds the $4\sigma$ level in PUDF and remains non-negligible in the $w$CDM framework. Using mock data generated from the Planck best-fit $\Lambda$CDM model, we find that PUDF and $\Lambda$CDM cannot be statistically distinguished, indicating that the precision of current data is insufficient to separate the two models. Overall, the apparent preference for $\Lambda$CDM may be driven by dataset inconsistencies rather than a genuine physical difference, leaving unified dark fluid models as viable alternatives within current observational limits. - oai:arXiv.org:2504.00536v4 + LITMUS: Bayesian Lag Recovery in Reverberation Mapping with Fast Differentiable Models + https://arxiv.org/abs/2505.09832 + arXiv:2505.09832v2 Announce Type: replace +Abstract: Reverberation mapping is a technique in which the mass of a Seyfert I galaxy's central supermassive black hole is estimated, along with the system's physical scale, from the timescale at which variations in brightness propagate through the galactic nucleus. This mapping allows for a long baseline of time measurements to extract spatial information beyond the angular resolution of our telescopes, and is the main means of constraining supermassive black hole masses at high redshift. The most recent generation of multi-year reverberation mapping campaigns for large numbers of active galactic nuclei (e.g. OzDES) have had to deal with persistent complications of identifying false positives, such as those arising from aliasing due to seasonal gaps in time-series data. We introduce LITMUS (Lag Inference Through the Mixed Use of Samplers), a modern lag recovery tool built on the "damped random walk" model of quasar variability, built in the autodiff framework JAX. LITMUS is purpose built to handle the multimodal aliasing of seasonal observation windows and provides evidence integrals for model comparison, a more quantified alternative to existing methods of lag validation. LITMUS also offers a flexible modular framework for extending modelling of AGN variability, and includes JAX-enabled implementations of other popular lag recovery methods like nested sampling and the interpolated cross correlation function. We test LITMUS on a number of mock light curves modelled after the OzDES sample and find that it recovers their lags with high precision and a successfully identifies spurious lag recoveries, reducing its false positive rate to drastically outperform the state of the art program JAVELIN. LITMUS's high performance is accomplished by an algorithm for mapping the Bayesian posterior density which both constrains the lag and offers a Bayesian framework for model null hypothesis testing. + oai:arXiv.org:2505.09832v2 + astro-ph.GA astro-ph.CO - gr-qc - hep-ph - hep-th - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.IM + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yan Su, Zhiqi Huang, Yanhong Yao, Junchao Wang, Jianqi Liu + http://creativecommons.org/licenses/by/4.0/ + Hugh G. McDougall, Tamara M. Davis, Benjamin J. S. Pope - On Validating Angular Power Spectral Models for the Stochastic Gravitational-Wave Background Without Distributional Assumptions - https://arxiv.org/abs/2504.16959 - arXiv:2504.16959v2 Announce Type: replace -Abstract: It is demonstrated that estimators of the angular power spectrum commonly used for the stochastic gravitational-wave background (SGWB) lack a closed-form analytical expression for the likelihood function and, typically, cannot be accurately approximated by a Gaussian likelihood. Nevertheless, a robust statistical analysis can be performed to enable the estimation and testing of angular power spectral models for the SGWB without specifying distributional assumptions. Here, the technical aspects of the method are discussed in detail. Moreover, a new, consistent estimator for the covariance of the angular power spectrum is derived. The proposed approach is applied to data from the third observing run (O3) of Advanced LIGO and Advanced Virgo. - oai:arXiv.org:2504.16959v2 - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + Unveiling the Ionized and Neutral ISM at z > 10 : The Origin of [O III] /[C II] Ratios from a Sub-parsec Resolution Radiative Transfer Simulation + https://arxiv.org/abs/2505.12397 + arXiv:2505.12397v3 Announce Type: replace +Abstract: Recent multi-wavelength observations by JWST and ALMA are unveiling both ionized and neutral ISM components in high-redshift ($z>6$) galaxies. In this work, we investigate the origin of rest-frame far-infrared [OIII]88 $\mu$m and [CII]158 $\mu$m emission by performing zoom-in cosmological simulations of dwarf-galaxy progenitors at $z=9-13$. Our simulations incorporate on-the-fly radiative transfer at sub-pc ($\sim$ 0.1 pc) resolution, allowing us to resolve the multi-phase ISM. We compute emission lines on a cell-by-cell basis, taking into account local temperature, density, metallicity, radiation field strength, column density, and spectral hardness of radiation bins. We find that [OIII] predominantly arises from centrally located ionizing bubbles with temperatures of $\sim (1-5)\times 10^4\,\mathrm{K}$ and high ionization parameters of $\log U_{\mathrm{ion}} \simeq -1.5$. In contrast, [CII] is produced in the surrounding dense neutral regions at $\sim 5\times 10^3\,\mathrm{K}$, which are heated by strong FUV radiation ($G/G_0 \sim 10^{3-5}$) from the central stellar clusters. This spatial arrangement leads to large local variations in [OIII]/[CII], ranging from $\sim$ 100 to 0.01. Our galaxy reproduces the global ratio [OIII]/[CII]$\sim5-30$, consistent with recent ALMA detections at $z>6$ without invoking enhanced O/C abundance ratios. We further derive that [OIII]/[CII] linearly scales with the mass and density ratios of ionized to neutral gas, $M_{\rm HII}/M_{\rm HI}$ and $n_{\rm HII}/n_{\rm HI}$ and show that the [OIII]/[CII] ratio typically changes from 5.7 to 0.3 from high-z to low-z. For future synergies of JWST and ALMA, we derived $M_{\rm HII}/M_{\rm HI}$ for observed $z >6$ galaxies using ${\rm H}\beta$ and [CII] and show the validity of our scaling relations. + oai:arXiv.org:2505.12397v3 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Xiangyu Zhang, Erik Floden, Hongru Zhao, Sara Algeri, Galin Jones, Vuk Mandic, Jesse Miller + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Yurina Nakazato, Kazuyuki Sugimura, Akio K. Inoue, Massimo Ricotti - SpiderCat: A Catalog of Compact Binary Millisecond Pulsars - https://arxiv.org/abs/2505.11691 - arXiv:2505.11691v4 Announce Type: replace -Abstract: We present SpiderCat, a multiwavelength catalog of all publicly known compact binary millisecond pulsars (MSPs) in the Galactic field. These systems, colloquially known as "spiders," consist of neutron stars in tight orbits with low-mass companions, which are gradually ablated by the pulsar wind. SpiderCat includes both primary subclasses$-$redbacks and black widows$-$distinguished by companion mass, as well as candidates and peculiar systems such as transitional, huntsman and tidarren MSPs. As of this initial release, SpiderCat contains 111 entries: 30 redbacks, 50 black widows, two huntsmans, 23 redback candidates, five black widow candidates, and one huntsman candidate. In this paper, we compile and summarize key parameters for each system, including spin and orbital properties, and multiwavelength data from radio, optical, X-ray, and $\gamma$-ray observations. An interactive, publicly accessible web interface, at https://astro.phys.ntnu.no/SpiderCAT, enables exploration and visualization of the data. The rapid growth of the number of known spiders, accelerated by the Fermi Large Area Telescope survey and its ability to identify MSPs in $\gamma$-rays, has opened the door to population-level studies. Utilizing SpiderCat, we analyze trends in spin period, orbital period, companion mass, emission properties, and spatial distribution. SpiderCat serves as a dynamic, multiwavelength repository for this unique class of binary pulsars, facilitating new discoveries and constraints on pulsar evolution, particle acceleration, and the neutron star equation of state. - oai:arXiv.org:2505.11691v4 - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Spatial and velocity anisotropies of stellar halos across cosmic web environments: Insights from IllustrisTNG simulation + https://arxiv.org/abs/2505.15127 + arXiv:2505.15127v2 Announce Type: replace +Abstract: The role of large-scale environment in shaping the structural and kinematic properties of stellar halos remains an open question. We investigate whether the cosmic web environments affect the spatial and velocity anisotropies of stellar halos in Milky Way-mass galaxies. Using high-resolution data from the TNG50 simulation, we analyze 29 stellar halos from each environment and quantify their spatial and kinematic anisotropies as a function of halo-centric radius. We find that stellar halos across all environments generally exhibit increasing spatial anisotropy with radius, with fluctuations corresponding to bound substructures. The velocity anisotropy profiles show radially dominated orbits on average, but also display significant local variation, including tangentially dominated regions. However, no statistically significant differences are observed in the mean spatial or velocity anisotropy profiles across environments, for either the total stellar halo population or for the in situ and ex situ components individually. The large scatter within each environment suggests that the formation of stellar halos is primarily driven by stochastic, small-scale processes such as satellite merger histories, rather than the large-scale geometry of the cosmic web. Our results imply that, at fixed halo mass, the influence of cosmic web environment on the structure of stellar halo is weak or highly non-deterministic. Possible environmental effects may be more prominent at higher masses where accretion is more anisotropic. Exploring this regime will require simulations with both larger volume and higher resolution. + oai:arXiv.org:2505.15127v2 + astro-ph.GA + astro-ph.CO + Fri, 19 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Karri I. I. Koljonen, Manuel Linares + 10.1093/mnras/staf2213 + Amit Mondal, Biswajit Pandey, Anindita Nandi - fftvis: A Non-Uniform Fast Fourier Transform Based Interferometric Visibility Simulator - https://arxiv.org/abs/2506.02130 - arXiv:2506.02130v2 Announce Type: replace -Abstract: The detection and characterization of the 21cm signal from the Epoch of Reionization (EoR) demands extraordinary precision in radio interferometric observations and analysis. For modern low-frequency arrays, achieving the dynamic range necessary to detect this signal requires simulation frameworks to validate analysis techniques and characterize systematic effects. However, the computational expense of direct visibility calculations grows rapidly with sky model complexity and array size, posing a potential bottleneck for scalable forward modeling. In this paper, we present fftvis, a high-performance visibility simulator built on the Flatiron Non-Uniform Fast-Fourier Transform (finufft) algorithm. We show that fftvis matches the well-validated matvis simulator to near numerical precision while delivering substantial runtime reductions, up to two orders of magnitude for dense, many-element arrays. We provide a detailed description of the fftvis algorithm and benchmark its computational performance, memory footprint, and numerical accuracy against matvis, including a validation study against analytic solutions for diffuse sky models. We further assess the utility of fftvis in validating 21cm analysis pipelines through a study of the dynamic range in simulated delay and fringe-rate spectra. Our results establish fftvis as a fast, precise, and scalable simulation tool for 21cm cosmology experiments, enabling end-to-end validation of analysis pipelines. - oai:arXiv.org:2506.02130v2 - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + Inferring and Interpreting the Visual Geometric Albedo and Phase Function of Earth + https://arxiv.org/abs/2507.22258 + arXiv:2507.22258v2 Announce Type: replace +Abstract: Understanding reflectance-related quantities for worlds enables effective comparative planetology and strengthens mission planning and execution. Measurements of these properties for Earth, especially its geometric albedo and phase function, have been difficult to achieve due to our Terrestrial situation -- it is challenging to obtain planetary-scale brightness measurements for the world we stand on. Using a curated dataset of visual (0.4--0.7 um) phase-dependent, disk-averaged observations of Earth taken from the ground and spacecraft, alongside a physical-statistical model, this work arrives at a definitive value for the visual geometric albedo of our planet: $0.242^{+0.005}_{-0.004}$. This albedo constraint is up 30--40% smaller than earlier, widely-quoted values. The physical-statistical model enables retrieval-like inferences to be performed on phase curves, and includes contributions from optically thick clouds, optically thin aerosols, Rayleigh scattering, ocean glint, gas absorption, and Lambertian surface reflectance. Detailed application of this inverse model to Earth's phase curve quantifies contributions of these different processes to the phase-dependent brightness of the Pale Blue Dot. Model selection identifies a scenario where aerosol forward scattering results in a false negative for surface habitability detection, which implies that aerosol forward scattering can effectively mimic an ocean glint signature in broadband visual phase curves. Observations of phase curves for Earth at redder-optical or near-infrared wavelengths could disentangle ocean glint effects from aerosol forward scattering. Finally, a review of albedos and planetary photometry is provided as well as a simple two-parameter fit to Earth's visual phase curve to ease adoption into other tools. + oai:arXiv.org:2507.22258v2 + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Tyler A. Cox, Steven G. Murray, Aaron R. Parsons, Joshua S. Dillon, Kartik Mandar, Zachary E. Martinot, Robert Pascua, Piyanat Kittiwisit, James E. Aguirre + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Tyler D. Robinson - Caustic fringes for wave dark matter - https://arxiv.org/abs/2506.02400 - arXiv:2506.02400v2 Announce Type: replace -Abstract: Wave dark matter is composed of particles sufficiently light that their de Broglie wavelength exceeds the average inter-particle separation. A typical wave dark matter halo exhibits granular substructures due to wave interference. In this paper, we explore the wave interference effects around caustics. These are locations of formally divergent density in cold collisionless systems. Examples include splashback in galaxy clusters, and tidal shells in merging galaxies, where the pile-up of dark matter close to apogee gives rise to caustics. We show that wave interference modifies the density profile in the vicinity of the caustics, giving rise to a fringe pattern well-described by the Airy function. This follows from approximating the gravitational potential as linear close to apogee. This prediction is verified in a series of numerical simulations in which the gravitational potential is computed exactly. We provide a formula expressing the fringe separation in terms of the wave dark matter mass and halo parameters, which is useful for interpreting and stacking data. The fringe separation near caustics can be significantly larger than the naive de Broglie scale (the latter set by the system's velocity dispersion). This opens up the possibility of detecting caustic fringes for a wide range of wave dark matter masses. - oai:arXiv.org:2506.02400v2 - astro-ph.CO + Spiral Structure Properties, Dynamics, and Evolution in MW-mass Galaxy Simulations + https://arxiv.org/abs/2507.22793 + arXiv:2507.22793v2 Announce Type: replace +Abstract: The structure of spiral galaxies is essential to understanding the dynamics and evolution of disk galaxies; however, the precise nature of spiral arms remains uncertain. Two challenges in understanding the mechanisms driving spirals are how galactic environment impacts spiral morphology and how they evolve over time. We present a catalog characterizing the properties, dynamics, and evolution of $m=2$ spiral structure in 10 Milky Way-mass galaxies from the FIRE-2 cosmological zoom-in simulations. Consistent with previous literature, we find that FIRE-2 spirals are transient, recurring features simultaneously present in the disk at varying pattern speeds ($\Omega_p$) that broadly decrease with radius. These spirals persist on Gyr timescales (mean duration 1.90 Gyr), but fluctuate in amplitude on timescales of hundreds of Myr. Tidal interactions and bar episodes impact the resulting $m=2$ spiral structure; strong satellite interactions generally produce shorter-lived, stronger spirals with larger radial extent, and bars can increase $\Omega_p$. Galactic environment influences spiral structure; kinematically colder disks can support longer-lived, stronger spirals. The properties of identified spirals in FIRE-2 vary widely in radial extent (0.3-10.8 kpc), duration (1.00-6.00 Gyr), and amplitudes ($a_{2,\text{max}}$=0.018-0.192). We find the presence of spirals in all age populations, suggesting these are density wave-driven features. This work represents the first time that spiral structure has been cataloged in this manner in cosmological simulations; the catalog can be leveraged with current and forthcoming observational surveys, enabling systematic comparisons to further our understanding of galaxy evolution. + oai:arXiv.org:2507.22793v2 astro-ph.GA - hep-ph - hep-th - Fri, 12 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Andrew Eberhardt, Lam Hui - - - Pulsar Sparking: What if mountains on the surface? - https://arxiv.org/abs/2506.12305 - arXiv:2506.12305v2 Announce Type: replace -Abstract: A numerical framework to calculate the height and potential of the vacuum inner gap of pulsars is presented here. % -The results demonstrate that small mountains on a pulsar's polar cap tend to significantly influence the properties of the inner vacuum gap, making it easier for sparks to form. % -In this scenario, the magnetospheric activity observed from the pulsars PSR J0250$+$5854 and PSR J2144$-$3933 which lie below the traditional pulsar death line, and some single-pulse modulation phenomena could also then be understood. % -Furthermore, the presence of small mountains should depend on the puzzling state of supranuclear matter inside pulsars. % -In order to sustain stable mountains on the surface, pulsars might be made of solid strangeon matter, which is favoured by both the charge neutrality and the flavour symmetry of quarks. - oai:arXiv.org:2506.12305v2 - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Zi-Hao Xu, Wei-Yang Wang, Shun-Shun Cao, Ren-Xin Xu + J. R. Quinn, S. R. Loebman, K. J. Daniel, L. Beraldo e Silva, A. Wetzel, V. P. Debattista, A. Arora, S. Ansar, F. McCluskey, D. Masoumi, J. Bailin - Cosmic sign-reversal: non-parametric reconstruction of interacting dark energy with DESI DR2 - https://arxiv.org/abs/2506.18477 - arXiv:2506.18477v2 Announce Type: replace -Abstract: A direct interaction between dark energy and dark matter provides a natural and important extension to the standard $\Lambda$CDM cosmology. We perform a non-parametric reconstruction of the vacuum energy ($w=-1$) interacting with cold dark matter using the cosmological data from DESI DR2, Planck CMB, and three SNIa samples (PP, DESY5, and Union3). By discretizing the coupling function $\beta(z)$ into 20 redshift bins and assuming a Gaussian smoothness prior, we reconstruct $\beta(z)$ without assuming any specific parameterization. The mean reconstructed $\beta(z)$ changes sign during cosmic evolution, indicating an energy transfer from cold dark matter to dark energy at early times and a reverse flow at late times. At high redshifts, $\beta(z)$ shows a $\sim 2\sigma$ deviation from $\Lambda$CDM. At low redshifts, the results depend on the SNIa sample: CMB+DESI and CMB+DESI+PP yield $\beta(z)$ consistent with zero within $2\sigma$, while CMB+DESI+DESY5 and CMB+DESI+Union3 prefer negative $\beta$ at $\sim2\sigma$. Both $\chi^2$ tests and Bayesian analyses favor the $\beta(z)$ model, with CMB+DESI DR2+DESY5 showing the most significant support through the largest improvement in goodness of fit ($\Delta\chi^2_{\rm MAP}=-17.76$) and strongest Bayesian evidence ($\ln\mathcal{B} = 5.98 \pm 0.69$). Principal component analysis reveals that the data effectively constrain three additional degrees of freedom in the $\beta(z)$ model, accounting for most of the improvement in goodness of fit. Our results demonstrate that the dynamical dark energy preference in current data can be equally well explained by such a sign-reversal interacting dark energy, highlighting the need for future observations to break this degeneracy. - oai:arXiv.org:2506.18477v2 - astro-ph.CO - gr-qc - hep-ph - hep-th - Fri, 12 Dec 2025 00:00:00 -0500 + Design and Commissioning of an LWA Swarm Station: The Long Wavelength Array -- North Arm + https://arxiv.org/abs/2508.09109 + arXiv:2508.09109v2 Announce Type: replace +Abstract: Modern radio interferometers are designed with increasingly sprawling geographical footprints, offering enhanced sensitivity and resolution. However, managing such extensive facilities presents operational challenges that can potentially impede or delay scientific progress. One solution to such obstacles is the `swarm telescope' concept which enables collaborative use of individual telescope systems, overseen by separate institutions, to create a more powerful and manageable facility. We present the design, construction, and commissioning of the Long Wavelength Array -- North Arm (LWA-NA) station, a prototype 64-element LWA Swarm telescope. LWA-NA is a cost-efficient, rapidly deployable platform for radio astronomy, and serves as a pathfinder for the larger LWA Swarm project. + oai:arXiv.org:2508.09109v2 + astro-ph.IM + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1088/1475-7516/2025/12/018 - JCAP 12 (2025) 018 - Yun-He Li, Xin Zhang + http://creativecommons.org/licenses/by/4.0/ + 10.1142/S2251171725500035 + C. A. Taylor, J. Dowell, G. B. Taylor, K. S. Obenberger, S. I. Chastain, J. Verastegui, L. E. Cordonnier, P. Kumar, E. Sheldahl, S. Bruzewski, T. Dolch, C. A. Siders - Metal-poor single Wolf-Rayet stars: The interplay of optically thick winds and rotation - https://arxiv.org/abs/2507.00137 - arXiv:2507.00137v3 Announce Type: replace -Abstract: The Small Magellanic Cloud (SMC) hosts 12 known Wolf-Rayet (WR) stars, seven of which are apparently single. Their formation is a challenge for current stellar evolution models because line-driven winds are generally assumed to be quenched at a metallicity of Z < 0.004. Here, we present a set of mesa models of single stars with zero-age main sequence masses of 20 - 80 Msun considering different initial rotation speeds ({\Omega} = 0 - 0.7 {\Omega}_c), metallicities (Z = 0.002 - 0.0045), and wind mass-loss models (optically thin and thick winds). We show that if we account for optically thick winds, fast rotating ({\Omega} = 0.6 {\Omega}_c) single metal-poor O-type stars (with M > 20 Msun) shed their envelope and become WR stars even at the low metallicity of the SMC. The luminosity, effective temperature, evolutionary timescale, surface abundance, and rotational velocity of our simulated WR stars are compatible to the WRs observed in the SMC. We speculate that this scenario can also alleviate the excess of giant stars across the Humphreys-Davidson limit. Our results have key implications for black hole masses, (pair instability) supernova explosions, and other observable signatures. - oai:arXiv.org:2507.00137v3 - astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + The Hidden Role of Anisotropies in Shaping Structure Formation in Cosmological N-Body Simulations + https://arxiv.org/abs/2508.13765 + arXiv:2508.13765v2 Announce Type: replace +Abstract: Initial conditions in cosmological $N$-body simulations are typically generated by displacing particles from a regular cubic lattice using a correlated field derived from the linear power spectrum, often via the Zel'dovich approximation. While this procedure reproduces the target two-point statistics (e.g., the power spectrum or correlation function), it introduces subtle anisotropies due to the underlying lattice structure. These anisotropies, invisible to angle-averaged diagnostics, become evident through directional measures such as the Angular Distribution of Pairwise Distances. Analyzing two Cold Dark Matter simulations with { varying resolutions and box sizes}, we show that these anisotropies are not erased but are amplified by gravitational evolution. They seed filamentary structures that persist into the linear regime, remaining visible even at redshift $z = 0$. Our findings demonstrate that such features are numerical artifacts -- emerging from the anisotropic coupling between the displacement field and the lattice -- not genuine predictions of an isotropic cosmological model. These results underscore the importance of critically reassessing how initial conditions are constructed, particularly when probing the large-scale, quasi-linear regime of structure formation. + oai:arXiv.org:2508.13765v2 + astro-ph.CO + cond-mat.stat-mech + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Lumen Boco, Michela Mapelli, Andreas A. C. Sander, Sofia Mesini, Varsha Ramachandran, Stefano Torniamenti, Erika Korb, Boyuan Liu, Gautham N. Sabhahit, Jorick S. Vink + http://creativecommons.org/licenses/by/4.0/ + Francesco Sylos Labini - Duration and properties of the embedded phase of star formation in 37 nearby galaxies from PHANGS-JWST - https://arxiv.org/abs/2507.01508 - arXiv:2507.01508v2 Announce Type: replace -Abstract: Light reprocessed by dust grains emitting in the infrared allows the study of the physics at play in dusty, embedded regions, where ultraviolet and optical wavelengths are attenuated. Infrared telescopes such as JWST have made it possible to study the earliest feedback phases, when stars are shielded by cocoons of gas and dust. This phase is crucial for unravelling the effects of feedback from young stars, leading to their emergence and the dispersal of their host molecular clouds. Here we show that the transition from the embedded to the exposed phase of star formation is short (< 4 Myr) and sometimes almost absent (< 1 Myr), across a sample of 37 nearby star-forming galaxies, covering a wide range of morphologies from massive barred spirals to irregular dwarfs. The short duration of the dust-clearing timescales suggests a predominant role of pre-supernova feedback mechanisms in revealing newborn stars, confirming previous results on smaller samples and allowing, for the first time, a statistical analysis of their dependencies. We find that the timescales associated with mid-infrared emission at 21 {\mu}m, tracing a dust-embedded feedback phase, are controlled by a complex interplay between giant molecular cloud properties (masses and velocity dispersions) and galaxy morphology. We report relatively longer durations of the embedded phase of star formation in barred spiral galaxies, while this phase is significantly reduced in low-mass irregular dwarf galaxies. We discuss tentative trends with gas-phase metallicity, which may favor faster cloud dispersal at low metallicities. - oai:arXiv.org:2507.01508v2 - astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Linear map-making with LuSEE-Night + https://arxiv.org/abs/2508.16773 + arXiv:2508.16773v2 Announce Type: replace +Abstract: LuSEE-Night is a pathfinder radio telescope on the lunar far side employing four 3-m monopole antennas arranged as two horizontal cross pseudo-dipoles on a rotational stage and sensitive to the radio sky in the 1-50 MHz frequency band. LuSEE-Night measures the corresponding 16 correlation products as a function of frequency. While each antenna combination measures radiation coming from a large area of the sky, their aggregate information as a function of phase in the lunar cycle and rotational stage position can be deconvolved into a low-resolution map of the sky. We study this deconvolution using linear map-making based on the Wiener filter algorithm. We illustrate how systematic effects can be effectively marginalised over as contributions to the noise covariance and demonstrate this technique on beam knowledge uncertainty and gain fluctuations. With reasonable assumptions about instrument performance, we show that LuSEE-Night should be able to map the sub-50 MHz sky at a ~5-degree resolution. + oai:arXiv.org:2508.16773v2 + astro-ph.IM + astro-ph.CO + astro-ph.SR + Fri, 19 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Lise Ramambason, M\'elanie Chevance, Jaeyeon Kim, Francesco Belfiore, J. M. Diederik Kruijssen, Andrea Romanelli, Amirnezam Amiri, M\'ed\'eric Boquien, Ryan Chown, Daniel A. Dale, Simthembile Dlamini, Oleg V. Egorov, Ivan Gerasimov, Simon C. O. Glover, Kathryn Grasha, Hamid Hassani, Hwihyun Kim, Kathryn Kreckel, Hannah Koziol, Adam K. Leroy, Jos\'e Eduardo M\'endez-Delgado, Justus Neumann, Lukas Neumann, Hsi-An Pan, Debosmita Pathak, Karin Sandstrom, Sumit K. Sarbadhicary, Eva Schinnerer, Jiayi Sun, Jessica Sutter, David A. Thilker, Leonardo Ubeda, Tony D. Weinbeck, Bradley C. Whitmore, Thomas G. Williams + Hugo Camacho, Kaja M. Rotermund, An\v{z}e Slosar, Stuart D. Bale, David W. Barker, Jack Burns, Christian H. Bye, Johnny Dorigo Jones, Adam Fahs, Keith Goetz, Sven Herrmann, Joshua J. Hibbard, Oliver Jeong, Marc Klein-Wolt, L\'eon V. E. Koopmans, Joel Krajewski, Zack Li, Corentin Louis, Milan Maksimovi\'c, Ryan McLean, Raul A. Monsalve, Paul O'Connor, Aaron Parsons, Michel Piat, Marc Pulupa, Rugved Pund, David Rapetti, Benjamin Saliwanchik, Graham Speedie, Nikolai Stefanov, David Sundkvist, Aritoki Suzuki, Harish K. Vedantham, Fatima Yousuf, Philippe Zarka - Earliest Galaxy Evolution in the CANUCS+Technicolor fields: Galaxy Properties at $z\sim10-16$ seen with the Full NIRCam Medium and Broad Band Filters - https://arxiv.org/abs/2507.03124 - arXiv:2507.03124v2 Announce Type: replace -Abstract: We present a sample of $z_{\rm phot}\sim10-16$ galaxies by exploiting one of the richest JWST NIRCam imaging data, taken in the CANUCS survey in Cycle 1 and the Technicolor (TEC) survey in Cycle 2. The combination of the CANUCS+TEC provides multi-epoch, deep NIRCam images in all medium bands (MBs) and broad bands (BBs) onboard NIRCam (22 filters in total), over $\sim23\ {\rm arcmin}^2$ in three independent lines of sight. We select high-$z$ galaxy candidates based on photometric redshifts, and obtain eight candidates at $z\sim10-16$, including a very robust candidate at $z\sim15.4$. The ultraviolet (UV) luminosity function (LF) from our sample is consistent with previous JWST studies showing a scatter of $\sim0.6$ dex across the literature, marking the significance of the field-to-field variance in interpreting galaxy abundance measurements at $z>10$. We find that the UV LF moderately evolves at $z>10$, and the LF normalization and the luminosity density decline by a factor of $\sim7$ from $z\sim11$ to $z\sim15$, indicating less steep evolution than $z<11$. We highlight the importance of MB filters, not only to minimize the contamination by low-$z$ interlopers but also to maximize the completeness. In particular, faint and less blue galaxies could be missed when the sample is built solely on BB data. The contamination and incompleteness of BB-only selected samples can bias our views of earliest galaxy evolution at $z>10$, including the UV LF by $\sim0.6$ dex, the size-magnitude relation by $\sim0.6$ dex, and the UV slope-magnitude relation by $\Delta\beta_{\rm UV}\sim-0.3$. - oai:arXiv.org:2507.03124v2 + J-VAR: Analysis of RR Lyrae light curves in seven optical bands + https://arxiv.org/abs/2509.03120 + arXiv:2509.03120v2 Announce Type: replace +Abstract: Context:RR Lyrae stars, with their accurate period and amplitude measurements, constrain stellar evolution and map Galactic structure. The Javalambre VARiability (J-VAR) survey is the time-domain extension of the Javalambre Photometric Local Universe survey, which provides time-series data across seven optical bands, including $gri$ and four medium and narrow bands. Aims: Our goal is to construct and analyze light curves for RR Lyrae stars identified in the J-VAR's first data release using the \textit{Gaia} third data release (DR3) Variable Stars catalog as a reference. Methods: The light curves of $315$ RR Lyrae were analyzed by fitting templates from the Sloan Digital Sky Survey Multiband Template Library. The periods and amplitudes for the seven bands in J-VAR were independently obtained from the best-fitted templates. Results: The J-VAR periods show strong agreement with \textit{Gaia} DR3 values. The Bailey diagram for each J-VAR filter shows larger pulsation amplitudes at bluer wavelengths. Amplitudes, after normalizing by the $r$-band amplitude, show an exponential trend, with the bluer J-VAR filter centered at $395~\text{nm}$ having twice the amplitude of the reddest J-VAR passband at $861~\text{nm}$. The normalized amplitudes of the RR Lyrae stars from {\it Gaia} and the Zwicky Transient Facility are consistent with the J-VAR trend. Finally, the SDSS templates derived from broadbands also provide a proper description for the medium and narrow band light curves. Conclusions: The J-VAR RR Lyrae catalog offers reliable pulsation parameters and light curves in seven optical filters, allowing the systematic study of amplitude trends from $395~\text{nm}$ to $860~\text{nm}$. + oai:arXiv.org:2509.03120v2 + astro-ph.SR astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yoshihisa Asada, Chris Willott, Adam Muzzin, Maru\v{s}a Brada\v{c}, Gabriel Brammer, Guillaume Desprez, Kartheik Iyer, Danilo Marchesini, Nicholas Martis, Ga\"el Noirot, Ghassan Sarrouh, Marcin Sawicki, Sunna Withers, Seiji Fujimoto, Giordano Felicioni, Ilias Goovaerts, Jon Jude\v{z}, Naadiyah Jagga, Maya Merchant, Rosa M\'erida, Luke Robbins + S. Kulkarni, H. V\'azquez Rami\'o, C. L\'opez-Sanjuan, S. Pyrzas, A. Ederoclite, F. Jim\'enez-Esteban, A. J. Cenarro, A. Mar\'in-Franch, J. Alcaniz, R. E. Angulo, D. Crist\'obal-Hornillos, R. A. Dupke, C. Hern\'andez-Monteagudo, M. Moles, L. Sodr\'e Jr., J. Varela - Collapsar Disk Outflows III: Detectable Neutrino and Gravitational Wave Signatures - https://arxiv.org/abs/2507.17836 - arXiv:2507.17836v2 Announce Type: replace -Abstract: We investigate the neutrino and gravitational wave (GW) signals from accretion disks formed during the failed collapse of a rotating massive star (a collapsar). Following black hole formation, a neutrino-cooled, shocked accretion disk forms, which displays non-spherical oscillations for a period of seconds before becoming advective and exploding the star. We compute the neutrino and GW signals (matter quadrupole, frequencies $\lesssim 100$ Hz) from collapsar disks using global axisymmetric, viscous hydrodynamic simulations. The neutrino signal with typical energies of O$(10)$ MeV is maximal during the neutrino-cooled (NDAF) phase that follows shock formation. This phase lasts for a few seconds and is easily detectable within O$(10-100)$ kpc by the IceCube Neutrino Telescope. Additional neutrino signatures from a precursor equatorial shock and by stochastic accretion plumes during the advective phase are detectable within the galaxy. The GW signal during the NDAF phase is detectable in the galaxy by current and next-generation ground-based observatories. The explosion (memory) GW signal is similar to that of standard core-collapse supernovae and can be probed with a deci-Hertz space-based detector. Shock oscillations during the NDAF phase impart time variations with frequency O$(10-100)$ Hz to the neutrino and GW signals, encoding information about the shock dynamics and inner disk. These time variations can be detectable in neutrinos by IceCube within O$(1-10)$ kpc depending on progenitor model, flavor transformation scenario, and detailed properties of the angular momentum transport mechanism. - oai:arXiv.org:2507.17836v2 - astro-ph.HE + Segmentation and Tracking of Eruptive Solar Phenomena with Convolutional Neural Networks + https://arxiv.org/abs/2509.05623 + arXiv:2509.05623v2 Announce Type: replace +Abstract: Solar eruptive events are complex phenomena, which most often include coronal mass ejections (CME), CME-driven compressive and shock waves, flares, and filament eruptions. CMEs are large eruptions of magnetized plasma from the Sun's outer atmosphere or corona, that propagate outward into the interplanetary space. Over the last several decades a large amount of remote solar eruption observational data has become available from ground-based and space-borne instruments. This has recently required the development of software approaches for automated characterisation of eruptive features. Most solar feature detection and tracking algorithms currently in use have restricted applicability and complicated processing chains, while complexity in engineering machine learning (ML) training sets limit the use of data-driven approaches for tracking or solar eruptive related phenomena. Recently, we introduced Wavetrack - a general algorithmic method for smart characterization and tracking of solar eruptive features. The method, based on a-trous wavelet decomposition, intensity rankings and a set of filtering techniques, allows to simplify and automate image processing and feature tracking. Previously, we applied the method successfully to several types of remote solar observations. Here we present the natural evolution of this approach. We discuss various aspects of applying Machine Learning (ML) techniques towards segmentation of high-dynamic range heliophysics observations. We trained Convolutional Neural Network (CNN) image segmentation models using feature masks obtained from the Wavetrack code. We present results from pre-trained models for segmentation of solar eruptive features and demonstrate their performance on a set of CME events based on SDO/AIA instrument data. + oai:arXiv.org:2509.05623v2 astro-ph.SR - gr-qc - hep-ph - nucl-th - Fri, 12 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Rodrigo Fern\'andez, Silas Janke, Coleman Dean, Irene Tamborra - - - The z = 9.625 Cosmic Gems Galaxy was a "Compact Blue Monster" Propelled by Massive Star Clusters - https://arxiv.org/abs/2507.18699 - arXiv:2507.18699v2 Announce Type: replace -Abstract: The recent discovery of five massive stellar clusters at z=9.625 in the Cosmic Gems has raised the question about the formation mechanism of star clusters in the first half Gyr after the Big-Bang. We infer the total stellar mass in clusters by normalizing and integrating the stellar cluster mass function (SCMF, dn(M)/dM ~ (n$_0$) $M^\beta$), assuming three different slopes $\beta$ = -1.5, -2.0 and -2.5 and different lower-mass limits between $10^2$ and $10^5$ Msun. The total integrated cluster stellar mass is compared to the stellar mass inferred from the counter-image of the Cosmic Gems, which provides the best, modestly magnified ($\mu$ = 1.84$\pm$0.05) representation of the entire galaxy. The delensed stellar mass of the Cosmic Gems galaxy is estimated as 3.5$_{-1.8}^{+3.3}$ x$10^7$ Msun, with an effective radius of Reff = 103$_{-15}^{+13}$ parsec and a stellar surface mass density of $\Sigma$mass = 520$_{-225}^{+340}$ Msun pc$^{-2}$. Accounting for normalization uncertainties - including different lensing magnification scenarios for the arc - a modified SCMF, combined with a significantly high star cluster formation efficiency (approaching 100%), appears to be a necessary condition to explain the relatively short formation timescale of both the star clusters and the counter-image, without exceeding the galaxy's stellar mass. By extrapolating the physical properties at the peak of the burst we find that in its recent past (<~ 30 Myr) the Cosmic Gems galaxy has likely experienced a specific star formation rate (sSFR) exceeding 25 Gyr$^{-1}$ and luminosity approaching the ``blue monster'' regime (M$_{UV}$ < -20). Our study provides insights into the extreme clustered nature of star formation in early galaxies and shed light into the formation of bound star clusters that might survive to z = 0 as globular clusters, older than 13 Gyr. - oai:arXiv.org:2507.18699v2 - astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.IM + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - E. Vanzella, M. Messa, A. Adamo, F. Loiacono, M. Oguri, K. Sharon, L. D. Bradley, P. Bergamini, M. Meneghetti, A. Claeyssens, B. Welch, M. Bradac, A. Zanella, A. Bolamperti, F. Calura, T. Y-Y. Hsiao, E. Zackrisson, M. Ricotti, L. Christensen, J. M. Diego, F. E. Bauer, X. Xu, S. Fujimoto, C. Grillo, M. Lombardi, P. Rosati, T. Resseguier, A. Zitrin, A. Bik, J. Richard, Abdurro'uf, R. Bhatawdekar, D. Coe, B. Frye, A. K. Inoue Y. Jimenez-Teja, C. Norman, J. R. Rigby, M. Trenti, T. Hashimoto + http://creativecommons.org/licenses/by-sa/4.0/ + Oleg Stepanyuk, Kamen Kozarev - Eccentricity distribution of extreme mass ratio inspirals - https://arxiv.org/abs/2509.02394 - arXiv:2509.02394v2 Announce Type: replace -Abstract: We present realistic eccentricity distributions for extreme mass ratio inspirals (EMRIs) forming via the two-body relaxation channel in nuclear star clusters, tracking their evolution up to the final plunge onto the central Schwarzschild massive black hole (MBH). We find that EMRIs can retain significant eccentricities at plunge, with a distribution peaking at $e_\mathrm{pl} \approx0.2$, and a considerable fraction reaching much higher values. In particular, up to $20\%$ of the forming EMRIs feature $e_\mathrm{pl} > 0.5$ for central MBH masses $M_\bullet$ in the range $10^5 \mathrm{M_\odot} \leq M_\bullet \leq 10^6 \mathrm{M_\odot}$, partially due to EMRIs forming at large semi-major axes and "cliffhanger EMRI", usually neglected in literature. This highlights the importance of accounting for eccentricity in waveform modeling and detection strategies for future space-based gravitational wave observatories such as the upcoming Laser Interferometer Space Antenna (LISA). Furthermore, we find that the numerical fluxes in energy and angular momentum currently implemented in the FastEMRIWaveforms (FEW) package may not adequately sample the full parameter space relevant to low-mass MBHs ($M_\bullet < 10^6 \mathrm{M_\odot}$), potentially limiting its predictive power in that regime. Specifically, for $M_\bullet=10^5 \mathrm{M_\odot}$ we find that about $75\%$ ($50 \%$) of EMRIs at 2 years (6 months) from plunge fall outside the currently available flux parameter space. Our findings motivate the development of extended flux grids and improved interpolation schemes to enable accurate modeling of EMRIs across a broader range of system parameters. - oai:arXiv.org:2509.02394v2 + A Spatial Gap in the Sky Distribution of Fast Radio Burst Detections Coinciding with Galactic Plasma Overdensities + https://arxiv.org/abs/2509.06721 + arXiv:2509.06721v2 Announce Type: replace +Abstract: We analyze the positional and morphological properties of about 3600 unique fast radio burst (FRB) sources reported in the second FRB catalog generated by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope. We find a two-dimensional dependence of FRB detections on sky position, and identify a significant absence of detections in a roughly circular region centered at Galactic coordinates (77.7$^\circ$, 0.9$^\circ$), spanning an area of 213.6 deg$^2$. This detection gap spatially coincides with the Cygnus X region $--$ a plasma-rich star-forming region in the Milky Way. This feature is most likely the result of increased sky temperature and strong multi-path scattering by turbulent ionized plasma, which broadens the FRB signals beyond detectability in the CHIME band. Our simulations yield a mean of 6 expected FRB detections within the gap when accounting for the elevated sky temperature in the direction of the detection gap. We infer that a lower limit of the maximum scattering timescale $\tau_{\rm sc,\, 1\,GHz} \geq 5.59$ ms, obtained without assuming a model of the Galactic electron distribution, is sufficient to suppress the brightness of all coincident FRBs. A similar suppression is seen in Catalog 2 along other high-emission measure (EM) sightlines (i.e., EM$\geq$2900 pc cm$^{-6}$), further supporting a broader trend of suppression due to Galactic scattering. Future very long baseline interferometry (VLBI) measurements of scattering disks with CHIME Outriggers could help confirm our interpretation. Our work highlights the notion that FRBs can serve as new, model-independent tracers of the warm ionized medium within our Milky Way Galaxy. + oai:arXiv.org:2509.06721v2 astro-ph.HE - astro-ph.GA - gr-qc - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Davide Mancieri, Luca Broggi, Morgan Vinciguerra, Alberto Sesana, Matteo Bonetti + http://creativecommons.org/licenses/by/4.0/ + Swarali Shivraj Patil, Robert A. Main, Emmanuel Fonseca, Kyle McGregor, B. M. Gaensler, Mohit Bhardwaj, Charanjot Brar, Amanda M. Cook, Alice P. Curtin, Gwendolyn Eadie, Ronniy Joseph, Lordrick Kahinga, Victoria Kaspi, Afrokk Khan, Bikash Kharel, Adam E. Lanman, Calvin Leung, Kiyoshi W. Masui, Mason Ng, Kenzie Nimmo, Ayush Pandhi, Aaron B. Pearlman, Ziggy Pleunis, Mawson W. Sammons, Ketan R. Sand, Paul Scholz, Kaitlyn Shin, Seth R. Siegel, Kendrick Smith - A milliarcsecond localization associates FRB 20190417A with a compact persistent radio source and an extreme magneto-ionic environment - https://arxiv.org/abs/2509.05174 - arXiv:2509.05174v2 Announce Type: replace -Abstract: We report the milliarcsecond localization of a high (1379 pc/cc) dispersion measure (DM) repeating fast radio burst, FRB 20190417A. Combining European VLBI Network detections of five repeat bursts, we confirm the FRB's host to be a low-metallicity, star-forming dwarf galaxy at z = 0.12817, similar to the hosts of FRBs 20121102A, 20190520B and 20240114A. We also confirm that it is associated with a previously reported persistent radio source (PRS), which is compact on milliarcsecond scales. Visibility-domain model fitting constrains the transverse physical size of the PRS to < 23 pc and yields an integrated flux density of 191(39) microJy at 1.4 GHz. Though we do not find significant evidence for DM evolution, FRB 20190417A exhibits a time-variable rotation measure (RM) ranging between +3958(11) and +5061(24) rad/m2 over three years. We find no evidence for intervening galaxy clusters in the FRB's line-of-sight and place a conservative lower limit on the rest-frame host DM contribution of 1228 pc/cc (90% confidence) -- the largest known for any FRB so far. This system strengthens the emerging picture of a rare subclass of repeating FRBs with large and variable RMs, above-average host DMs, and luminous PRS counterparts in metal-poor dwarf galaxies. Our results suggest that these systems are the result of environmental selection, or a distinct engine for FRB emission. - oai:arXiv.org:2509.05174v2 + SN 2024aecx: a fast-evolving Type IIb supernova with a prominent shock-cooling peak + https://arxiv.org/abs/2509.12343 + arXiv:2509.12343v3 Announce Type: replace +Abstract: SN 2024aecx is a nearby ($\sim$11 Mpc) Type IIb SN discovered within $\sim$1 d after explosion. In this paper we report high-cadence photometric (typically 0.5$\sim$1 day) and spectroscopic follow-up observations, conducted from as early as 0.27 d post discovery out to the nebular phase at 158.4 d. We analyze the environment of SN 2024aecx and derive a new distance (11.3$\pm$1.1 Mpc), metallicity and host extinction. The light curve exhibits a hot and luminous shock-cooling peak at the first few days, followed by a main peak with very rapid post-maximum decline. The earliest spectra are blue and featureless, while from 2.3 d after discovery prominent P-Cygni profiles emerge. At nebular phase, the emission lines exhibit asymmetric and double-peaked profiles, indicating asphericity and/or early dust formation in the ejecta. Nebular spectral modelling indicates a blueshifted O-rich clump moving toward observer, and the $[\text{OI}]/[\text{CaII}]$ line ratio suggests an intermediate-mass progenitor. We simulated the progenitor and explosion using a two-component model of shock cooling and radioactive $^{56}$Ni heating; our model favors an extended, low-mass H-rich envelope with $M_{\mathrm{e}} = 0.04\pm{0.01} M_{\odot}$ and a low ejecta mass of$M_{\mathrm{ej}} = 1.55^{+0.18}_{-0.14} M_{\odot}$. And the nebular-phase spectra and light-curve modelling both suggest that it most likely originated from an intermediate-mass binary progenitor system. The comprehensive monitoring of SN 2024aecx, coupled with the detailed characterization of its local environment, establishes it as a benchmark event for probing the progenitors and explosion mechanisms of Type IIb SNe. + oai:arXiv.org:2509.12343v3 + astro-ph.SR astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Alexandra M. Moroianu, Shivani Bhandari, Maria R. Drout, Jason W. T. Hessels, Dant\'e M. Hewitt, Franz Kirsten, Benito Marcote, Ziggy Pleunis, Mark P. Snelders, Navin Sridhar, Uwe Bach, Emmanuel K. Bempong-Manful, Vladislavs Bezrukovs, Richard Blaauw, Justin D. Bray, Salvatore Buttaccio, Shami Chatterjee, Alessandro Corongiu, Roman Feiler, B. M. Gaensler, Marcin P. Gawro\'nski, Marcello Giroletti, Adaeze L. Ibik, Ramesh Karuppusamy, Mattias Lazda, Calvin Leung, Michael Lindqvist, Kiyoshi W. Masui, Daniele Michilli, Kenzie Nimmo, Omar S. Ould-Boukattine, Ayush Pandhi, Zsolt Paragi, Aaron B. Pearlman, Weronika Puchalska, Paul Scholz, Kaitlyn Shin, Jurjen J. Sluman, Matteo Trudu, David Williams-Baldwin, Jun Yang + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Qiang Xi, Ning-Chen Sun, David Aguado, Ismael P'erez-Fournon, Fr'ed'erick Poidevin, Junjie Jin, Yiming Mao, Zexi Niu, Beichuan Wang, Yu Zhang, Kuntal Misra, Divyanshu Janghel, Justyn R. Maund, Amit Kumar, Samaporn Tinyanont, Liang-Duan Liu, Yu-Hao Zhang, Bhavya Ailawadhi, Monalisa Dubey, Zhen Guo, Anshika Gupta, Min He, Dhruv Jain, Debalina Kar, Wenxiong Li, Joe D. Lyman, Haiyang Mu, Kumar Pranshu, Xinxiang Sun, Lingzhi Wang, Sarvesh Kumar Yadav, Yi-Han Zhao, Jie Zheng, Yinan Zhu, David L'opez Fern'andez-Nespral, Alicia L'opez Oramas, Yanan Wang, Klaas Wiersema, Jifeng Liu - First Light for the GRAVITY+ Adaptive Optics: Extreme Adaptive Optics for the Very Large Telescope Interferometer - https://arxiv.org/abs/2509.21431 - arXiv:2509.21431v2 Announce Type: replace -Abstract: GRAVITY+ improves by orders of magnitude the sensitivity, sky-coverage and contrast of the Very Large Telescope Interferometer (VLTI). A central part of this project is the development of Gravity Plus Adaptive Optics (GPAO), a dedicated high-order and laser-guide star Adaptive Optics (AO) system for VLTI. GPAO consists of four state-of-the-art AO systems equipping all 8m-class Unit Telescopes (UTs) for the wavefront correction of the VLTI instruments. It offers both visible and infrared Natural Guide Star (NGS) and Laser Guide Star (LGS) operations. The paper presents the design, operations and performances of GPAO. We illustrate the improvement brought by GPAO with interferometric observations obtained during the commissioning of the NGS mode end-2024. These science results include the first optical interferometry observations of a redshift $z\sim4$ quasar, the spectroscopy of a cool brown-dwarf with magnitude $K\sim 21.0$, the first observations of a Class I young star with GRAVITY, and the first sub-micro arcsecond differential astrometry in the optical. Together with the entire GRAVITY+ project, the implementation of GPAO is a true paradigm shift for observing the optical Universe at very high angular resolution. - oai:arXiv.org:2509.21431v2 + Backtracking Bipolar Magnetic Regions to their emergence: Two groups and their implication in the tilt measurements + https://arxiv.org/abs/2509.17157 + arXiv:2509.17157v2 Announce Type: replace +Abstract: Bipolar Magnetic Regions (BMRs) that appear on the solar photosphere are surface manifestations of the Suns internal magnetic field. With modern observations and continuous data streams, the study of BMRs has moved from manual sunspot catalogs to automated detection and tracking methods. In this work, we present an additional module to the existing BMR tracking algorithm, AutoTAB, that focuses on identifying emerging signatures of BMRs. Specifically, for regions newly detected on the solar disk, this module backtracks the BMRs to their point of emergence. From a total of about 12,000 BMRs identified by AutoTAB, we successfully backtracked 3,080 cases. Within this backtracked sample, we find two distinct populations. One group shows the expected behavior of emerging regions, in which the magnetic flux increases significantly during the emerging phase. The other group consists of BMRs whose flux, however, does not exhibit substantial growth during their evolution, the instances where our algorithm fails to capture the initial emergence of the BMRs. We classify these as discarded BMRs and examine their statistical properties separately. Our analysis shows that these discarded BMRs do not display any preferred tilt angle distribution and do not show systematic latitudinal tilt dependence, in contrast to the trends typically associated with emerging BMRs. This indicates that including such regions in statistical studies of BMR properties can distort or mask the underlying physical characteristics. We therefore emphasise the importance of excluding the discarded population from the whole dataset when analysing the statistical behavior of BMRs. + oai:arXiv.org:2509.17157v2 + astro-ph.SR astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - GRAVITY+ Collaboration, :, F. Allouche, C. Bailet, M. Benisty, A. Berdeu, J. -P. Berger, P. Berio, A. Bigioli, C. Blanchard, O. Boebion, H. Bonnet, G. Bourdarot, P. Bourget, W. Brandner, J. Brul\'e, P. Burgos, M. Carbillet, C. Correia, B. Courtney Barrer, S. Curaba, R. Davies, D. Defr\`ere, A. Delboulb\'e, F. Delplancke, R. Dembet, A. Drescher, N. Dubost, A. Eckart, C. \'Edouard, F. Eisenhauer, L. Esteras Otal, M. Fabricius, H. Feuchtgruber, P. F\'edou, G. Finger, N. M. F\"orster Schreiber, R. Frahm, E. Garcia, P. Garcia, R. Garcia Lopez, R. Genzel, J. P. Gil, S. Gillessen, T. Gomes, F. Gont\'e, V. Gopinath, C. Gouvret, J. Graf, P. Guajardo, S. Guieu, W. Hackenberg, M. Hartl, X. Haubois, F. Hau{\ss}mann, T. Henning, P. Hibon, S. H\"onig, M. Horrobin, M. Houll\'e, N. Hubin, I. Ibn Taieb, L. Jochum, L. Jocou, A. Jost, J. Kammerer, L. Karl, A. Kaufer, P. Kern, P. Kervella, J. Kolb, H. Korhonen, L. Kreidberg, P. Krempl, S. Lacour, S. Lagarde, O. Lai, V. Lapeyr\`ere, R. Laugier, V. Leal, J. -B. Le Bouquin, J. Leftley, P. L\'ena, B. Lopez, D. Lutz, Y. Magnard, F. Mang, A. Marcotto, D. Maurel, A. M\'erand, F. Millour, M. Montarges, N. More, N. Moruj\~ao, T. Moulin, H. Nowacki, M. Nowak, S. Oberti, T. Ott, L. Pallanca, F. Patru, T. Paumard, K. Perraut, G. Perrin, P. O. Petrucci, R. Petrov, O. Pfuhl, N. Pourr\'e, S. Rabien, C. Rau, M. Riquelme, S. Robbe-Dubois, S. Rochat, M. Salman, J. S\'anchez-Berm\'udez, J. Schubert, J. Scigliuto, P. Shchekaturov, N. Schuhler, J. Shangguan, T. Shimizu, S. Scheithauer, C. Soenke, F. Soulez, E. Stadler, J. Stadler, C. Straubmeier, E. Sturm, M. Subroweit, C. Sykes, L. J. Tacconi, K. R. W. Tristram, S. Uysal, S. von Fellenberg, F. Widmann, E. Wieprecht, E. Wiezorrek, J. Woillez, S. Yazici, G. Zins + Anu Sreedevi, Bidya Binay Karak, Bibhuti Kumar Jha, Rambahadur Gupta, Dipankar Banerjee - The Most Probable Behaviour of the Dark Energy Equation of State Indicates a Thawing Quintessence Field: Tomographic Alcock-Paczy\'nski Test with Redshift-Space Correlation Function II - https://arxiv.org/abs/2510.24089 - arXiv:2510.24089v3 Announce Type: replace -Abstract: We apply an extended Alcock-Paczy\'nski (AP) test to the Sloan Digital Sky Survey data to constrain the dark energy models with the Chevallier-Polarski-Linder (CPL) parametrization of the dark energy equation of state. The extended AP test method uses the full shape of redshift-space two-point correlation funcion(CF) as the standard shape in order to measure the expansion history of the universe. We calibrate the standard shape by using the cosmology-dependent nonlinear evolution of the CF shape in the Multiverse simulations. Further validation of the method and calibration of possible systematics are performed based on mock samples from the Horizon Run 4 simulation. Using the AP test alone, we constrain the flat CDM plus CPL-type dark energy model (flat $w^{\rm CPL}$CDM) to have $\Omega_m=0.290_{-0.031}^{+0.029}$, $w_0=-0.800_{-0.100}^{+0.208}$, and $w_a=-0.238_{-0.972}^{+0.650}$. When combined with other results from the low-redshift universe, such as the Pantheon$+$ supernova compilation and DESI BAO data, the constraint on dark energy becomes $w_0=-0.857_{-0.042}^{+0.051}$, and $w_a=-0.153_{-0.356}^{+0.347}$. The best-fit $w^{CPL}(z)$ suggests no phantom-divide crossing at $z<0.7$, and the dark energy behaviour is consistent with a thawing quintessence field. It is only when the CMB data are combined with late-time cosmological probes that a phantom-divide crossing at low redshift is favored. - oai:arXiv.org:2510.24089v3 - astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + JWST occultation reveals unforeseen complexity in Chariklo's ring system + https://arxiv.org/abs/2510.06366 + arXiv:2510.06366v2 Announce Type: replace +Abstract: Ring systems have been discovered around several small bodies in the outer Solar System through stellar occultations. While such measurements provide key information about ring geometry and dynamical interactions, little is known about their origins, lifetimes, evolutionary pathways, or compositions. Here we report near-infrared observations with the James Webb Space Telescope (JWST) of a stellar occultation by (10199) Chariklo, a Centaur known to host a double-ring system. Our JWST measurements show that Chariklo's inner dense ring has become significantly more opaque than in previous observations, pointing to ongoing replenishment processes or dynamical restructuring. In contrast, the outer ring exhibits a much weaker near-infrared occultation signature than seen in earlier visible-light detections. This discrepancy may reflect material loss, suggesting that the outer ring could be transient, or may arise from wavelength-dependent opacity. These scenarios, which are not mutually exclusive, point to an unprecedented level of complexity in small-body ring systems, distinct from those observed around any other minor bodies in the Solar System. + oai:arXiv.org:2510.06366v2 + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Fuyu Dong, Changbom Park + Pablo Santos-Sanz, Altair R. Gomes-J\'unior, Bruno E. Morgado, Yucel Kilic, Csilla E. Kalup, Csaba Kiss, Chrystian L. Pereira, Bryan J. Holler, Nicol\'as Morales, Jos\'e Luis Ortiz, Bruno Sicardy, Juan Luis Rizos, John Stansberry, Richard G. French, Heidi B. Hammel, Zhong-Yi Lin, Damya Souami, Josselin Desmars, Stefanie N. Milam, Felipe Braga-Ribas, Marcelo Assafin, Gustavo Benedetti-Rossi, Julio I. B. Camargo, Ren\'e Duffard, Flavia L. Rommel, Estela Fern\'andez-Valenzuela, Noem\'i Pinilla-Alonso, M\'onica Vara-Lubiano - Pre-flight Background Estimates for COSI - https://arxiv.org/abs/2510.25304 - arXiv:2510.25304v2 Announce Type: replace -Abstract: The Compton Spectrometer and Imager (COSI) is a Compton telescope designed to survey the 0.2 - 5 MeV sky, consisting of a compact array of cross-strip germanium detectors. It is planned to be launched in 2027 into an equatorial low-Earth (530 km) orbit with a prime mission duration of 2 years. The observation of MeV gamma rays is dominated by background, mostly from extragalactic and atmospheric photon but also from the activation of the detector materials induced by cosmic-ray interactions. Thus, background simulation and identification are crucial for the data analysis. In this work we perform Monte Carlo simulations of the background for the first 3 months in orbit, and we extrapolate the results to 2 years in orbit, in order to determine the build-up of the activation due to long-lived isotopes. We determine the rates of events induced by the background that are reconstructed as Compton events in the simulated COSI data. We find that the extragalactic background photons dominate at low energies (<660 keV), while delayed activation from cosmic-ray primaries (proton/alpha) and albedo photons dominate at higher energies. As part of this work, a comparison at low latitude (<1 deg) between recent measurement of the SAA by the High-Energy Particle Detector (HEPD-01) on board the China Seismo-Electromagnetic Satellite (CSES-01) and the AP9/AE9 model has been made, showing an overestimation of the flux by a factor 9 by the model. The systematic uncertainties associated with these components are quantified. This work marks a major step forward in estimating and understanding the expected background rates for the COSI satellite mission. - oai:arXiv.org:2510.25304v2 - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + What is the contribution of gravitational infall on the mass assembly of star-forming clouds? A case study in a numerical simulation of the interstellar medium + https://arxiv.org/abs/2510.09480 + arXiv:2510.09480v2 Announce Type: replace +Abstract: Star formation in galaxies is a complex phenomenon occurring on a very wide range of scales, and molecular clouds are at the heart of this process. The formation of these structures and the subsequent collapse of the gas within them to form new stars remain unresolved scientific questions. In particular, the role and importance of gravity at between the disk scale height and prestellar cores (100 to 0.01 pc) are still topics of debate. In this work, we conduct a case study examining the mass assembly and evolution of a giant molecular cloud complex in a numerical stratified-box simulation of the interstellar medium with photo-ionizing and supernova driving and resolving down to scales $\gtrsim 1$ pc and densities up to $10^3$ cm$^{-3}$. By introducing tracer particles to precisely track the forces acting on the gas during its evolution towards and within the clouds, we are able to quantify how much of the mass inflow is driven by the self-gravity of the gas and the gravity from the stellar disk. We find that up to 20% of the gas is gravity-driven at a scale of 100 pc, contributing 10% of the inflow from the warm to the cold phase and 20% from the cold phase to the individual molecular clouds, reaching up to 45% inside the molecular gas, at densities $\gtrsim 400$ cm$^{-3}$. However, at the 100 pc scale, the contribution of gravity-driven gas on the linewidth is negligible. We conclude that the bulk of the gas motions assembling the clouds in our simulation are caused by the supernova-driven supersonic turbulence, which results in locally convergent flows, with a small contribution from the stellar gravitational potential. + oai:arXiv.org:2510.09480v2 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Savitri Gallego, Uwe Oberlack, Jan Lommler, M. Christopher Karwin, Francesco Fenu, Valentina Fioretti, Andreas Zoglauer, F. M. Follega, A. Perinelli, Roberto Battiston, Roberto Iuppa, E. Steven Boggs, Saurabh Mittal, Pierre Jean, Carolyn Kierans, H. Dieter Hartmann, A. John Tomsick + http://creativecommons.org/licenses/by-sa/4.0/ + No\'e Brucy, Enrique V\'azquez-Semadeni, Tine Colman, J\'er\'emy Fensch, Ralf S. Klessen - Investigating episodic mass loss in evolved massive stars IV. Comprehensive analysis of dusty red supergiants in NGC 6822, IC 10, and WLM - https://arxiv.org/abs/2510.26674 - arXiv:2510.26674v2 Announce Type: replace -Abstract: Mass loss shapes the fate of massive stars; however, the physical mechanism causing it remains uncertain. We present a comprehensive analysis of seven red supergiants, for which we searched evidence of episodic mass loss, in three low-metallicity galaxies: NGC~6822, IC~10, and WLM. Initially, the spectral classification of their optical spectra was refined and compared to previous reported classifications, finding four sources that display spectral variability. We derived the physical properties of five of them using the \textsc{marcs} atmospheric models corrected for nonlocal thermal equilibrium effects to measure stellar properties from our new near-infrared spectra, such as the effective temperature, surface gravity, metallicity, and microturbulent velocity. Additional empirical and theoretical methods were employed to calculate effective temperatures, finding consistent results. We constructed optical and infrared light curves, discovering two targets in NGC~6822 with photometric variability between 1 and 2.5 mag in amplitude in r and ~ 0.5 mag in the mid-infrared. Furthermore, we discovered a candidate-dimming event in one of these sources. Periods for three red supergiants were determined using epoch photometry, which were consistent with the empirical estimations from literature period-luminosity relations. Our comprehensive analysis of all the available data for each target provides evidence for episodic mass loss in four red supergiants. - oai:arXiv.org:2510.26674v2 + Eclipsing Stellar Flare on the Demon Star Algol Binary System Observed during the MAXI-NICER Follow-up Campaign in 2018 + https://arxiv.org/abs/2510.14587 + arXiv:2510.14587v2 Announce Type: replace +Abstract: Algol is a well-known eclipsing binary hosting an active and variable star that exhibits frequent stellar flares. Here, we report our pre-planned and coordinated rapid X-ray follow-up observations of an eclipsing flare on Algol. The Monitor of All-sky X-ray Image (MAXI) detected a flare on Algol at 05:52 UT on 2018 July 4. Subsequently, we carried out a prompt X-ray monitoring with the Neutron star Interior Composition Explorer (NICER) starting at 19:45 UT on the same day, and the observation ended at 06:02 UT on 2018 July 6. During the decaying phase of the flare, we successfully detected a 5.8-hour-long eclipse, corresponding to the secondary eclipse in which Algol A blocks the line of sight to Algol B. During the eclipse, the 2-10 keV X-ray flux is decreased to 20% level from $1.9\times10^{-10}~ \mathrm{erg~cm^{-2}~s^{-1} }$ to $4.5\times10^{-11}~ \mathrm{erg~cm^{-2}~s^{-1} }$. We found a configuration of the flare size and location to explain the X-ray observations; e.g., the flare occurred at the latitude 45{\deg}S of the Algol B surface with a flare height of $1.9\times10^{11}~\mathrm{cm}$, corresponding to 0.8 times the stellar radius of Algol B, giving 80% obscuration of the flare loop by Algol A. The apparent absorption increase before the eclipse might originate from coronal mass ejection (CME) in the line of sight ejected during the flare. + oai:arXiv.org:2510.14587v2 astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.HE + Fri, 19 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - 10.1051/0004-6361/202554071 - E. Christodoulou (IAASARS, National Observatory of Athens, National and Kapodistrian University of Athens, Department of Physics), S. de Wit (IAASARS, National Observatory of Athens, National and Kapodistrian University of Athens, Department of Physics), A. Z. Bonanos (IAASARS, National Observatory of Athens), G. Mu\~noz-Sanchez (IAASARS, National Observatory of Athens, National and Kapodistrian University of Athens, Department of Physics), G. Maravelias (IAASARS, National Observatory of Athens, Institute of Astrophysics FORTH), A. Ruiz (IAASARS, National Observatory of Athens), K. Antoniadis (IAASARS, National Observatory of Athens, National and Kapodistrian University of Athens, Department of Physics), D. Garc\'ia-\'Alvarez (Instituto de Astrof\'isica de Canarias, Grantecan S. A., Centro de Astrof\'isica de La Palma), M. M. Rubio D\'iez (Centro de Astrobiolog\'ia, CSIC-INTA) + Kazuya Nakayama, Wataru Buz Iwakiri, Teruaki Enoto, Shun Inoue, Yuta Notsu, Keith Gendreau, Zaven Arzoumanian, Kenji Hamaguchi, Tatehiro Mihara - Direct multi-model dark-matter search with gravitational-wave interferometers using data from the first part of the fourth LIGO-Virgo-KAGRA observing run - https://arxiv.org/abs/2510.27022 - arXiv:2510.27022v4 Announce Type: replace -Abstract: Gravitational-wave detectors can probe the existence of dark matter with exquisite sensitivity. Here, we perform a search for three kinds of dark matter -- dilatons (spin-0), dark photons (spin-1) and tensor bosons (spin-2) -- using three independent methods on the first part of the most recent data from the fourth observing run of LIGO--Virgo--KAGRA. Each form of dark matter could have interacted with different standard-model particles in the instruments, causing unique differential strains on the interferometers. While we do not find any evidence for a signal, we place the most stringent upper limits to-date on each of these models. For scalars with masses between $[4\times 10^{-14},1.5\times 10^{-13}]$ eV that couple to photons or electrons, our constraints improve upon those from the third observing run by one order of magnitude, with the tightest limit of $\sim 10^{-20}\,\text{GeV}^{-1}$ at a mass of $\sim2\times 10^{-13}\text{ eV}$. For vectors with masses between $[7\times 10^{-13},8.47\times 10^{-12}]$ eV that couple to baryons, our constraints supersede those from MICROSCOPE and E\"ot-Wash by one to two orders of magnitude, reaching a minimum of $\sim 5\times 10^{-24}$ at a mass of $\sim 10^{-12}$ eV. For tensors with masses of $[4\times 10^{-14},8.47\times 10^{-12}]$ eV (the full mass range analyzed) that couple via a Yukawa interaction, our constraints surpass those from fifth-force experiments by four to five orders of magnitude, achieving a limit as low as $\sim 8\times 10^{-9}$ at $\sim2\times 10^{-13}$ eV. Our results show that gravitational-wave interferometers have become frontiers for new physics and laboratories for direct multi-model dark-matter detection. - oai:arXiv.org:2510.27022v4 + Variance of dust temperature and spectral index in Planck polarization data using spin-moment expansion + https://arxiv.org/abs/2510.18305 + arXiv:2510.18305v2 Announce Type: replace +Abstract: Thermal dust is the major polarized foreground hindering the detection of primordial cosmic microwave background (CMB) B-modes. Its signal exhibits complex behavior in frequency space, arising from the combined variation in our Galaxy of the orientation of magnetic fields and the spectral properties of dust grains aligned with magnetic field lines. In this work, we present a new framework for analyzing the thermal dust signal using polarized microwave data. We introduce residual maps, represented as complex quantities, which capture deviations of the local polarized spectral energy distribution (SED) from the mean complex SED averaged over the sky mask. We present simple predictions that relate the values of the statistical correlation and covariances between the residual maps to the physical properties of the emitting aligned grains. Testing these predictions provides valuable information about the nature of the dust signal. We evaluated our predictions using Planck data over a 97% mask excluding the inner Galactic plane. Despite its simplicity, our model captures a significant part of the statistical properties of the data. For the SRoll2 version of the data, the spectral dependence of the covariances between residual maps is compatible with a dust model that includes only temperature variations rather than spectral index variations. In contrast, for the PR4 Planck official release, it is incompatible with both models. Our methodology can be used to analyze future high-precision polarization data and to build more accurate dust models for use by the CMB community. + oai:arXiv.org:2510.18305v2 + astro-ph.GA astro-ph.CO - gr-qc - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu, S. Albanesi, W. Ali, S. Al-Kershi, C. All\'en\'e, A. Allocca, S. Al-Shammari, P. A. Altin, S. Alvarez-Lopez, W. Amar, O. Amarasinghe, A. Amato, F. Amicucci, C. Amra, A. Ananyeva, S. B. Anderson, W. G. Anderson, M. Andia, M. Ando, M. Andr\'es-Carcasona, T. Andri\'c, J. Anglin, S. Ansoldi, J. 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Moore, D. Moraru, A. More, S. More, C. Moreno, E. A. Moreno, G. Moreno, A. Moreso Serra, S. Morisaki, Y. Moriwaki, G. Morras, A. Moscatello, M. Mould, B. Mours, C. M. Mow-Lowry, L. Muccillo, F. Muciaccia, D. Mukherjee, Samanwaya Mukherjee, Soma Mukherjee, Subroto Mukherjee, Suvodip Mukherjee, N. Mukund, A. Mullavey, H. Mullock, J. Mundi, C. L. Mungioli, M. Murakoshi, P. G. Murray, D. Nabari, S. L. Nadji, A. Nagar, N. Nagarajan, K. Nakagaki, K. Nakamura, H. Nakano, M. Nakano, D. Nanadoumgar-Lacroze, D. Nandi, V. Napolano, P. Narayan, I. Nardecchia, T. Narikawa, H. Narola, L. Naticchioni, R. K. Nayak, L. Negri, A. Nela, C. Nelle, A. Nelson, T. J. N. Nelson, M. Nery, A. Neunzert, S. Ng, L. Nguyen Quynh, S. A. Nichols, A. B. Nielsen, Y. Nishino, A. Nishizawa, S. Nissanke, W. Niu, F. Nocera, J. Noller, M. Norman, C. North, J. Novak, R. Nowicki, J. F. Nu\~no Siles, L. K. Nuttall, K. Obayashi, J. Oberling, J. O'Dell, E. Oelker, M. Oertel, G. Oganesyan, T. O'Hanlon, M. Ohashi, F. Ohme, R. Oliveri, R. Omer, B. O'Neal, M. Onishi, K. Oohara, B. O'Reilly, M. Orselli, R. O'Shaughnessy, S. O'Shea, S. Oshino, C. Osthelder, I. Ota, D. J. Ottaway, A. Ouzriat, H. Overmier, B. J. Owen, R. Ozaki, A. E. Pace, R. Pagano, M. A. Page, A. Pai, L. Paiella, A. Pal, S. Pal, M. A. Palaia, M. P\'alfi, P. P. Palma, C. Palomba, P. Palud, H. Pan, J. Pan, K. C. Pan, P. K. Panda, Shiksha Pandey, Swadha Pandey, P. T. H. Pang, F. Pannarale, K. A. Pannone, B. C. Pant, F. H. Panther, M. Panzeri, F. Paoletti, A. Paolone, A. Papadopoulos, E. E. Papalexakis, L. Papalini, G. Papigkiotis, A. Paquis, A. Parisi, B. -J. Park, J. Park, W. Parker, G. Pascale, D. Pascucci, A. Pasqualetti, R. Passaquieti, L. Passenger, D. Passuello, O. Patane, A. V. Patel, D. Pathak, A. Patra, B. Patricelli, B. G. Patterson, K. Paul, S. Paul, E. Payne, T. Pearce, M. Pedraza, A. Pele, F. E. Pe\~na Arellano, X. Peng, Y. Peng, S. Penn, M. D. Penuliar, A. Perego, Z. Pereira, C. P\'erigois, G. Perna, A. Perreca, J. Perret, S. Perri\`es, J. W. Perry, D. Pesios, S. Peters, S. Petracca, C. Petrillo, H. P. Pfeiffer, H. Pham, K. A. Pham, K. S. Phukon, H. Phurailatpam, M. Piarulli, L. Piccari, O. J. Piccinni, M. Pichot, M. Piendibene, F. Piergiovanni, L. Pierini, G. Pierra, V. Pierro, M. Pietrzak, M. Pillas, F. Pilo, L. Pinard, I. M. Pinto, M. Pinto, B. J. Piotrzkowski, M. Pirello, M. D. Pitkin, A. Placidi, E. Placidi, M. L. Planas, W. Plastino, C. Plunkett, R. Poggiani, E. Polini, J. Pomper, L. Pompili, J. Poon, E. Porcelli, E. K. Porter, C. Posnansky, R. Poulton, J. Powell, G. S. Prabhu, M. Pracchia, B. K. Pradhan, T. Pradier, A. K. Prajapati, K. Prasai, R. Prasanna, P. Prasia, G. Pratten, G. Principe, G. A. Prodi, P. Prosperi, P. Prosposito, A. C. Providence, A. Puecher, J. Pullin, P. Puppo, M. P\"urrer, H. Qi, M. Qiao, J. Qin, G. Qu\'em\'ener, V. Quetschke, P. J. Quinonez, N. Qutob, R. Rading, I. Rainho, S. Raja, C. Rajan, B. Rajbhandari, K. E. Ramirez, F. A. Ramis Vidal, M. Ramos Arevalo, A. Ramos-Buades, S. Ranjan, K. Ransom, P. Rapagnani, B. Ratto, A. Ravichandran, A. Ray, V. Raymond, M. Razzano, J. Read, T. Regimbau, S. Reid, C. Reissel, D. H. Reitze, V. Rella, A. I. Renzini, B. Revenu, A. Revilla Pe\~na, R. Reyes, L. Ricca, F. Ricci, M. Ricci, A. Ricciardone, J. Rice, J. W. Richardson, M. L. Richardson, A. Rijal, K. Riles, H. K. Riley, S. Rinaldi, J. Rittmeyer, C. Robertson, F. Robinet, M. Robinson, A. Rocchi, L. Rolland, J. G. Rollins, A. E. Romano, R. Romano, A. Romero, I. M. Romero-Shaw, J. H. Romie, S. Ronchini, T. J. Roocke, L. Rosa, T. J. Rosauer, C. A. Rose, D. Rosi\'nska, M. P. Ross, M. Rossello-Sastre, S. Rowan, S. K. Roy, S. Roy, D. Rozza, P. Ruggi, N. Ruhama, E. Ruiz Morales, K. Ruiz-Rocha, S. Sachdev, T. Sadecki, P. Saffarieh, S. Safi-Harb, M. R. Sah, S. Saha, T. Sainrat, S. Sajith Menon, K. Sakai, Y. Sakai, M. Sakellariadou, S. Sakon, O. S. Salafia, F. Salces-Carcoba, L. Salconi, M. Saleem, F. Salemi, M. Sall\'e, S. U. Salunkhe, S. Salvador, A. Salvarese, A. Samajdar, A. Sanchez, E. J. Sanchez, L. E. Sanchez, N. Sanchis-Gual, J. R. Sanders, E. M. S\"anger, F. Santoliquido, F. Sarandrea, T. R. Saravanan, N. Sarin, P. Sarkar, A. Sasli, P. Sassi, B. Sassolas, B. S. Sathyaprakash, R. Sato, S. Sato, Yukino Sato, Yu Sato, O. Sauter, R. L. Savage, T. Sawada, H. L. Sawant, S. Sayah, V. Scacco, D. Schaetzl, M. Scheel, A. Schiebelbein, M. G. Schiworski, P. Schmidt, S. Schmidt, R. Schnabel, M. Schneewind, R. M. S. Schofield, K. Schouteden, B. W. Schulte, B. F. Schutz, E. Schwartz, M. Scialpi, J. Scott, S. M. Scott, R. M. Sedas, T. C. Seetharamu, M. Seglar-Arroyo, Y. Sekiguchi, D. Sellers, N. Sembo, A. S. Sengupta, E. G. Seo, J. W. Seo, V. Sequino, M. Serra, A. Sevrin, T. Shaffer, U. S. Shah, M. A. Shaikh, L. Shao, A. K. Sharma, Preeti Sharma, Prianka Sharma, Ritwik Sharma, S. Sharma Chaudhary, P. Shawhan, N. S. Shcheblanov, E. Sheridan, Z. -H. Shi, M. Shikauchi, R. Shimomura, H. Shinkai, S. Shirke, D. H. Shoemaker, D. M. Shoemaker, R. W. Short, S. ShyamSundar, A. Sider, H. Siegel, D. Sigg, L. Silenzi, L. Silvestri, M. Simmonds, L. P. Singer, Amitesh Singh, Anika Singh, D. Singh, N. Singh, S. Singh, A. M. Sintes, V. Sipala, V. Skliris, B. J. J. Slagmolen, D. A. Slater, T. J. Slaven-Blair, J. Smetana, J. R. Smith, L. Smith, R. J. E. Smith, W. J. Smith, S. Soares de Albuquerque Filho, M. Soares-Santos, K. Somiya, I. Song, S. Soni, V. Sordini, F. Sorrentino, H. Sotani, F. Spada, V. Spagnuolo, A. P. Spencer, P. Spinicelli, A. K. Srivastava, F. Stachurski, C. J. Stark, D. A. Steer, N. Steinle, J. Steinlechner, S. Steinlechner, N. Stergioulas, P. Stevens, M. StPierre, M. D. Strong, A. Strunk, A. L. Stuver, M. Suchenek, S. Sudhagar, Y. Sudo, N. Sueltmann, L. Suleiman, K. D. Sullivan, J. Sun, L. Sun, S. Sunil, J. Suresh, B. J. Sutton, P. J. Sutton, K. Suzuki, M. Suzuki, B. L. Swinkels, A. Syx, M. J. Szczepa\'nczyk, P. Szewczyk, M. Tacca, H. Tagoshi, K. Takada, H. Takahashi, R. Takahashi, A. Takamori, S. Takano, H. Takeda, K. Takeshita, I. Takimoto Schmiegelow, M. Takou-Ayaoh, C. Talbot, M. Tamaki, N. Tamanini, D. Tanabe, K. Tanaka, S. J. Tanaka, S. Tanioka, D. B. Tanner, W. Tanner, L. Tao, R. D. Tapia, E. N. Tapia San Mart\'in, C. Taranto, A. Taruya, J. D. Tasson, J. G. Tau, D. Tellez, R. Tenorio, H. Themann, A. Theodoropoulos, M. P. Thirugnanasambandam, L. M. Thomas, M. Thomas, P. Thomas, J. E. Thompson, S. R. Thondapu, K. A. Thorne, E. Thrane, J. Tissino, A. Tiwari, Pawan Tiwari, Praveer Tiwari, S. Tiwari, V. Tiwari, M. R. Todd, M. Toffano, A. M. Toivonen, K. Toland, A. E. Tolley, T. Tomaru, V. Tommasini, T. Tomura, H. Tong, C. Tong-Yu, A. Torres-Forn\'e, C. I. Torrie, I. Tosta e Melo, E. Tournefier, M. Trad Nery, K. Tran, A. Trapananti, R. Travaglini, F. Travasso, G. Traylor, M. Trevor, M. C. Tringali, A. Tripathee, G. Troian, A. Trovato, L. Trozzo, R. J. Trudeau, T. Tsang, S. Tsuchida, L. Tsukada, K. Turbang, M. Turconi, C. Turski, H. Ubach, T. Uchiyama, R. P. Udall, T. Uehara, K. Ueno, V. Undheim, L. E. Uronen, T. Ushiba, M. Vacatello, H. Vahlbruch, N. Vaidya, G. Vajente, A. Vajpeyi, J. Valencia, M. Valentini, S. A. Vallejo-Pe\~na, S. Vallero, V. Valsan, M. van Dael, E. Van den Bossche, J. F. J. van den Brand, C. Van Den Broeck, M. van der Sluys, A. Van de Walle, J. van Dongen, K. Vandra, M. VanDyke, H. van Haevermaet, J. V. van Heijningen, P. Van Hove, J. Vanier, M. VanKeuren, J. Vanosky, N. van Remortel, M. Vardaro, A. F. Vargas, V. Varma, A. N. Vazquez, A. Vecchio, G. Vedovato, J. Veitch, P. J. Veitch, S. Venikoudis, R. C. Venterea, P. Verdier, M. Vereecken, D. Verkindt, B. Verma, Y. Verma, S. M. Vermeulen, F. Vetrano, A. Veutro, A. Vicer\'e, S. Vidyant, A. D. Viets, A. Vijaykumar, A. Vilkha, N. Villanueva Espinosa, V. Villa-Ortega, E. T. Vincent, J. -Y. Vinet, S. Viret, S. Vitale, H. Vocca, D. Voigt, E. R. G. von Reis, J. S. A. von Wrangel, W. E. Vossius, L. Vujeva, S. P. Vyatchanin, J. Wack, L. E. Wade, M. Wade, K. J. Wagner, L. Wallace, E. J. Wang, H. Wang, J. Z. Wang, W. H. Wang, Y. F. Wang, G. Waratkar, J. Warner, M. Was, T. Washimi, N. Y. Washington, D. Watarai, B. Weaver, S. A. Webster, N. L. Weickhardt, M. Weinert, A. J. Weinstein, R. Weiss, L. Wen, K. Wette, J. T. Whelan, B. F. Whiting, C. Whittle, E. G. Wickens, D. Wilken, A. T. Wilkin, B. M. Williams, D. Williams, M. J. Williams, N. S. Williams, J. L. Willis, B. Willke, M. Wils, L. Wilson, C. W. Winborn, J. Winterflood, C. C. Wipf, G. Woan, J. Woehler, N. E. Wolfe, H. T. Wong, I. C. F. Wong, K. Wong, T. Wouters, J. L. Wright, M. Wright, B. Wu, C. Wu, D. S. Wu, H. Wu, K. Wu, Q. Wu, Y. Wu, Z. Wu, E. Wuchner, D. M. Wysocki, V. A. Xu, Y. Xu, N. Yadav, H. Yamamoto, K. Yamamoto, T. S. Yamamoto, T. Yamamoto, R. Yamazaki, T. Yan, F. Yang, K. Z. Yang, Y. Yang, Z. Yarbrough, J. Yebana, S. -W. Yeh, A. B. Yelikar, X. Yin, J. Yokoyama, T. Yokozawa, S. Yuan, H. Yuzurihara, M. Zanolin, M. Zeeshan, T. Zelenova, J. -P. Zendri, M. Zeoli, M. Zerrad, M. Zevin, L. Zhang, N. Zhang, R. Zhang, T. Zhang, C. Zhao, Yue Zhao, Yuhang Zhao, Z. -C. Zhao, Y. Zheng, H. Zhong, H. Zhou, H. O. Zhu, Z. -H. Zhu, A. B. Zimmerman, L. Zimmermann, M. E. Zucker, J. Zweizig, J. Shu + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Vincent Guillet, L\'eo Vacher, Jonathan Aumont, Fran\c{c}ois Boulanger, Alessia Ritacco, Jean-Marc Delouis, Andrea Bracco - Dynamical Masses and Radiative Transfer Modeling of HD 698: a Be Binary in Evolutionary Transition - https://arxiv.org/abs/2511.02523 - arXiv:2511.02523v3 Announce Type: replace -Abstract: We present a detailed analysis of the early post-mass-transfer binary HD 698 (V742 Cas) combining high-resolution optical spectroscopy, long-baseline interferometry, and radiative-transfer modeling. Counter-phased radial-velocity curves yield a circular orbit with P=55.927+/-0.001 d and component masses M_Be=7.48+/-0.07 M_sun and M_comp=1.23+/-0.02 M_sun. The Be primary is traced by broad H alpha wings, while narrow metallic absorption lines arise from a slowly rotating companion. The interferometric separation implies a dynamical distance of 888+/-5 pc. The spectral energy distribution is reproduced with E(B-V)=0.321+/-0.016 and a viscous decretion disk of base density rho_0~5x10^-12 g cm^-3 at r=R_eq, declining radially as rho(r)~r^-n with n=3.0. The companion is luminous and inflated, with T_eff=10.0(+0.2,-0.1) kK, R_comp=13.1+/-0.2 R_sun, and log(L/L_sun)=3.19, contributing significantly to the flux (L_comp/L_Be~0.3). Spectral line mismatches further suggest a hydrogen-poor, CNO-processed atmosphere, consistent with a stripped-envelope star. HD 698 thus adds to the emerging class of Be+bloated OB binaries, capturing a brief post-mass-transfer phase when the donor remains spectroscopically detectable prior to the subdwarf stage. - oai:arXiv.org:2511.02523v3 - astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + An accurate measure of the size of dark matter halos using the size of galaxies + https://arxiv.org/abs/2510.19926 + arXiv:2510.19926v2 Announce Type: replace +Abstract: The physically motivated definition of galaxy size proposed recently, linked to the farther location of the in situ star formation, considerably reduces the scatter of the galaxy mass-size relation and provides a viable method to infer the galaxy stellar mass from its size. We provide a similar relation correlating the size of galaxies with the size of their dark matter haloes by leveraging the small scatter of the aforementioned relation. We analysed the simulated galaxies of the two main cosmological volumes of the EAGLE simulations and computed the size of the galaxies and their mass when mimicking the observational analysis. For central galaxies, we computed the relation between galaxy size and halo size. We show that the simulated galaxies reproduce the observed stellar mass-size relation's normalisation and slope. The scatter of this relation, 0.06 dex, matches the intrinsic scatter measured in observation. We then computed the correlation between galaxy size and halo size and found that the relation is steeper than when using the half-mass radius as a measure of size, with the scatter (0.1 dex) being a factor of two smaller than the observed relation. As well, the galaxy-to-halo mass relation derived from the simulations provides a factor of two better scatter than the observed scatter. This opens the possibility of measuring the size of dark matter haloes with greater accuracy (less than 50%, i.e. around six times better than using the effective radius) by using only deep imaging data. + oai:arXiv.org:2510.19926v2 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.3847/1538-4357/ae17bf - Ilfa A. Gabitova (Faculty of Physics and Technology, Al-Farabi Kazakh National University, Almaty, Kazakhstan), Alex C. Carciofi (Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Sao Paulo, Brazil), Tajan H. de Amorim (Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Sao Paulo, Brazil), Mark Suffak (Department of Physics and Astronomy, Western University, London, Canada), Anatoly S. Miroshnichenko (Department of Physics and Astronomy, University of North Carolina at Greensboro, USA, Fesenkov Astrophysical Institute, Almaty, Kazakhstan), Sergey V. Zharikov (Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ensenada, Mexico), Amanda C. Rubio (School of Physics and Astronomy, University of Leeds, Leeds, UK), Steve Danford (Department of Physics and Astronomy, University of North Carolina at Greensboro, USA), Alicia N. Aarnio (Department of Physics and Astronomy, University of North Carolina at Greensboro, USA), Peter Prendergast (Kernersville Observatory, Winston-Salem, USA), Richard J. Rudy (Kookoosint Scientific, Camarillo, USA), Richard C. Puetter (Center for Astrophysics and Space Science, University of California San Diego, USA), R. Brad Perry (Alabaster Scientific, Irvington, USA), Aldiyar T. Agishev (Faculty of Physics and Technology, Al-Farabi Kazakh National University, Almaty, Kazakhstan), Nadezhda L. Vaidman (Faculty of Physics and Technology, Al-Farabi Kazakh National University, Almaty, Kazakhstan, Fesenkov Astrophysical Institute, Almaty, Kazakhstan), Serik A. Khokhlov (Faculty of Physics and Technology, Al-Farabi Kazakh National University, Almaty, Kazakhstan, Fesenkov Astrophysical Institute, Almaty, Kazakhstan) + http://creativecommons.org/licenses/by/4.0/ + Claudio Dalla Vecchia, Ignacio Trujillo - On the Exoplanet Yield of Gaia Astrometry - https://arxiv.org/abs/2511.04673 - arXiv:2511.04673v3 Announce Type: replace -Abstract: We re-examine the expected yield of Gaia astrometric planet detections using updated models for giant-planet occurrence, the local stellar population, and Gaia's demonstrated astrometric precision. Our analysis combines a semi-analytic model that clarifies key scaling relations with more realistic Monte Carlo simulations. We predict $7{,}500 \pm 2{,}100$ planet discoveries in the 5-year dataset (DR4) and $120{,}000 \pm 22{,}000$ over the full 10-year mission (DR5), with the dominant error arising from uncertainties in giant-planet occurrence. We evaluate the sensitivity of these forecasts to the detection threshold and the desired precision for measurements of planet masses and orbital parameters. Roughly $1{,}900 \pm 540$ planets in DR4 and $38{,}000 \pm 7{,}300$ planets in DR5 should have masses and orbital periods determined to better than $20$%. Most detections will be super-Jupiters ($3$ - $13 M_{\rm J}$) on $2$ - $5$AU orbits around GKM-type stars ($0.4$ - $1.3 M_\odot$) within $500$ pc. Unresolved binary stars will lead to spurious planet detections, but we estimate that genuine planets will outnumber them by a factor of $5$ or more. An exception is planets around M-dwarfs with $a < 1$AU, for which the false-positive rate is expected to be about $50$%. To support community preparation for upcoming data releases, we provide mock catalogs of Gaia exoplanets and planet-impostor binaries. - oai:arXiv.org:2511.04673v3 - astro-ph.EP - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 + A volcanic chronosequence as a time-resolved paleo-detector array to study the cosmic-ray flux in the Late Pleistocene and Holocene + https://arxiv.org/abs/2510.23126 + arXiv:2510.23126v2 Announce Type: replace +Abstract: We present a phenomenological study demonstrating the feasibility of using olivine xenoliths from the Cha\^ine des Puys as a time-resolved paleo-detector array to probe the cosmic-ray flux over the last 40,000 years. This volcanic region provides a unique chronosequence of samples brought to the surface by well-dated eruptions. By modeling the expected density of nuclear recoil tracks induced by cosmic-ray muons in olivine, we show that the signal is detectable and above backgrounds from natural radioactivity. We demonstrate that by analyzing samples with different exposure ages, it is possible to construct a time-differential measurement of the cosmic-ray flux. This method shows sensitivity to historical variations, such as the enhanced flux expected during the Laschamp geomagnetic excursion ($\sim$41~kyr) and the potential contribution from nearby supernovae, for which we use the Antlia supernova remnant precursor as a benchmark. This work establishes a new application of the paleo-detector technique for long-scale time-domain high-energy astrophysics and provides the direct scientific motivation for experimental efforts to measure these track records. + oai:arXiv.org:2510.23126v2 + astro-ph.HE + hep-ph + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Caleb Lammers, Joshua N. Winn + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Claudio Galelli, Lorenzo Caccianiga, Lorenzo Apollonio, Paolo Magnani, Vincent Breton - Finite Lifetime Fragment Model 4 for Striae Formation in the Dust Tails of Comets (FLM 4) Acceleration by Lorenz-force - https://arxiv.org/abs/2511.05753 - arXiv:2511.05753v3 Announce Type: replace -Abstract: The striations in the dust tails of comets are referred to as striae, and their origin has long been a mystery. We introduce a new dynamic model to describe the forms of the striae observed in comets Hale-Bopp (C/1995 O1), West (C/1975 V1), and Seki-Lines (C/1962 C1). Charged particles made of refractory materials, with radii less than 0.5micrometer, are expelled from the comet's nucleus and accelerated by Lorentz forces near the nucleus. These particles decay many times to form striae, which have a lifespan of less than about 100 days at a distance of 1 astronomical unit from the sun. Over time, they continue to decay and eventually disappear from view. The following dynamic model explains these material science processes. Particles expelled from the comet's nucleus are subjected to three forces: solar gravity, solar radiation pressure, and Lorentz forces near the nucleus. As these particles decrease in size, the Lorentz forces and radiation pressure cause fluctuations, increasing and decreasing to form striae. This model, which is less of a dynamic approximation than previous theories (FLM3), explains the structure of the striae, enables predictions of their luminosity, and clarifies their origin. - oai:arXiv.org:2511.05753v3 + Rapid Brightening of 3I/ATLAS Ahead of Perihelion + https://arxiv.org/abs/2510.25035 + arXiv:2510.25035v2 Announce Type: replace +Abstract: Interstellar comet 3I/ATLAS has been approaching its 2025 October 29 perihelion while opposite the Sun from Earth, hindering ground-based optical observations over the preceding month. However, this geometry placed the comet within the fields of view of several space-based solar coronagraphs and heliospheric imagers, enabling its continued observation during its final approach toward perihelion. We report photometry from STEREO-A's SECCHI HI1 and COR2, SOHO's LASCO C3, and GOES-19's CCOR-1 instruments in 2025 September--October, which show a rapid rise in the comet's brightness scaling with heliocentric distance r as r^(-7.5+/-1.0). CCOR-1 also resolves the comet as an extended source with an apparent coma ~4' in diameter. Furthermore, LASCO color photometry shows the comet to be distinctly bluer than the Sun, consistent with gas emission contributing a substantial fraction of the visible brightness near perihelion. + oai:arXiv.org:2510.25035v2 astro-ph.EP - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kimihiko Nishioka + Qicheng Zhang, Karl Battams - High-impact Scientific Software in Astronomy and its creators - https://arxiv.org/abs/2511.12195 - arXiv:2511.12195v2 Announce Type: replace -Abstract: In the last decades, scientific software has graduated from a hidden side-product to a first-class member of the astrophysics literature. We aim to quantify the activity and impact of software development for astronomy, using a systematic survey. Starting from the Astrophysics Source Code Library and the Journal of Open Source Software, we analyse 3432 public git-based scientific software packages. Paper abstract text analysis suggests seven dominant themes: cosmology, data reduction pipelines, exoplanets, hydrodynamic simulations, radiative transfer spectra simulation, statistical inference and galaxies. We present key individual software contributors, their affiliated institutes and countries of high-impact software in astronomy & astrophysics. We consider the number of citations to papers using the software and the number of person-days from their git repositories, as proxies for impact and complexity, respectively. We find that half of the mapped development is through US-affiliated institutes, and a large number of high-impact projects are led by a single person. Our results indicate that there are currently over 200 people active on any given day to improve software in astronomy. - oai:arXiv.org:2511.12195v2 - astro-ph.IM - physics.soc-ph - Fri, 12 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by-nc-sa/4.0/ - 10.3847/25c2cfeb.fe9c1f84 - Bulletin of the AAS, 2025, Dec 11, Volume 57 - Johannes Buchner - - - High-Precision Multi-Period Analysis of the Ellipsoidal Variable Candidate TIC~470127886 from TESS Photometry - https://arxiv.org/abs/2511.13610 - arXiv:2511.13610v2 Announce Type: replace -Abstract: We present the first detailed photometric characterization of TIC 470127886, a previously unstudied multi-periodic variable star discovered in TESS photometry. Analysis of 145,374 high-cadence observations spanning 696 days (944-day baseline, 2023 January-2024 October) across 10 sectors (60, 59, 58, 53, 52, 73, 86, 79, 78, 85) reveals complex periodic variability with a primary period of 5.544527 +/- 0.004307 days and false alarm probability 1.47 x 10^-87. Lomb-Scargle analysis identifies three significant periods at 5.545, 5.801, and 8.874 days with amplitudes of 15,702, 12,772, and 12,670 ppm. The phase-folded light curve shows smooth, sinusoidal morphology consistent with ellipsoidal variation from tidal distortion in a close binary, with no eclipse features. A three-component sinusoidal model, appropriate for ellipsoidal variables, provides excellent fit quality. Validation tests confirm signal authenticity and persistence, and systematic checks verify no contamination from nearby stars (>3 mag fainter). We classify TIC 470127886 as an ellipsoidal variable candidate with 0.70 confidence, with multi-period behavior suggesting additional variability mechanisms beyond tidal distortion. This work demonstrates high-precision characterization of complex multi-periodic variables in TESS photometry. - oai:arXiv.org:2511.13610v2 - astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + Oscillations of dark matter halos in galaxies and their effects on motion of stars + https://arxiv.org/abs/2511.20952 + arXiv:2511.20952v2 Announce Type: replace +Abstract: Matter and dark matter in galaxies represent two main components linked by the gravitational interaction. Collisions of galaxies may create an offset between the centres of mass of these components. Ignoring the internal dynamics of particles in the dark matter halo and the Keplerian rotation of matter in the galaxy, we focus on the possible relative oscillations of the matter component as a whole within the dark matter halo. We estimate the amplitude and frequency of these oscillations assuming that the offset of the centres of mass is small as compared with the size of the galaxy. Such oscillations, if exist, should manifest themselves in anomalies of velocities of stars in the galaxy, such as the density waves and runaway stars which have orbit periods in resonance with oscillations. + oai:arXiv.org:2511.20952v2 + astro-ph.GA + astro-ph.CO + hep-ph + Fri, 19 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Roo Weerasinghe + V. V. Flambaum, I. B. Samsonov - Advancing Identification method of Gamma-Ray Bursts with Data and Feature Enhancement - https://arxiv.org/abs/2511.15470 - arXiv:2511.15470v2 Announce Type: replace -Abstract: Gamma-ray bursts (GRBs) are challenging to identify due to their transient nature, complex temporal profiles, and limited observational datasets. We address this with a one-dimensional convolutional neural network integrated with an Adaptive Frequency Feature Enhancement module and physics-informed data augmentation. Our framework generates 100,000 synthetic GRB samples, expanding training data diversity and volume while preserving physical fidelity-especially for low-significance events. The model achieves 97.46% classification accuracy, outperforming all tested variants with conventional enhancement modules, highlighting enhanced domain-specific feature capture. Feature visualization shows model focuses on deep-seated morphological features and confirms the capability of extracting physically meaningful burst characteristics. Dimensionality reduction and clustering reveal GRBs with similar morphologies or progenitor origins cluster in the feature space, linking learned features to physical properties. This perhaps offers a novel diagnostic tool for identifying kilonova- and supernova-associated GRB candidates, establishing criteria to enhance multi-messenger early-warning systems. The framework aids current time-domain surveys, generalizes to other rare transients, and advances automated detection in large-volume observational data. - oai:arXiv.org:2511.15470v2 - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Dynamical Dark Energy and the Unresolved Hubble Tension: Multi-model Constraints from DESI 2025 and Other Probes + https://arxiv.org/abs/2512.07281 + arXiv:2512.07281v2 Announce Type: replace +Abstract: We present a Bayesian comparative analysis of five cosmological models: $\Lambda$CDM, $w$CDM, $w_0w_a$CDM, $\phi$CDM (with scalar-field dark energy), and an interacting dark energy scenario (the $\xi$-index model), to investigate dark energy evolution and the Hubble tension. Utilizing the latest data from the Dark Energy Spectroscopic Instrument (DESI) DR2 (Baryon Acoustic Oscillations, BAO), Pantheon+ (Type Ia Supernovae, SNIa), and Cosmic Microwave Background (CMB) data (including lensing) from \textit{Planck} and the Atacama Cosmology Telescope (ACT), we report three key findings. First, the Hubble constant ($H_0$) inferred from the combined data consistently aligns with early-universe measurements across all models, indicating a persistent Hubble tension. Second, we find compelling evidence for dynamical dark energy: early-universe (CMB) constraints favor a phantom phase (with an equation-of-state parameter $w < -1$), while late-universe (BAO/SNIa) data prefer quintessence ($w > -1$). Third, the full dataset suggests a late-time interaction between dark energy and matter. Our results demonstrate that dark energy evolves with cosmic time, challenging the cosmological constant paradigm. + oai:arXiv.org:2512.07281v2 + astro-ph.CO + Fri, 19 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Peng Zhang, Bing Li, Ren-Zhou Gui, Shao-Lin Xiong, Yu Wang, Shi-Jie Zheng, Guang-Cheng Xiao, Xiao-Bo Li, Yue Huang, Chen-Wei Wang, Jia-Cong Liu, Yan-Qiu Zhang, Wang-Chen Xue, Chao Zheng, Yue Wang + Zhuoming Zhang, Tengpeng Xu, Yun Chen - The FAST-SETI Milky Way Globular Cluster Survey I: A Pilot Multibeam On-the-Fly Search of Five Globular Clusters at L-Band - https://arxiv.org/abs/2511.21085 - arXiv:2511.21085v2 Announce Type: replace -Abstract: We report a narrowband technosignature search toward five Milky Way globular clusters (NGC 6171, NGC 6218, NGC 6254, NGC 6838, and IC 1276) using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) 19-beam L-band receiver (1.05-1.45 GHz). We adapt the MultiBeam Point-source Scanning (MBPS) strategy to extended targets by gating detections to generalized on-target windows (gOTWs), i.e. the time intervals when a beam main lobe intersects a buffered cluster mask, and by enforcing the deterministic multibeam illumination sequence as a geometry test. Dynamic spectra with frequency resolution about 7.5 Hz and time resolution about 10 s are searched with turboSETI over drift rates |nu_dot| <= 4 Hz s^-1 at signal-to-noise ratio S/N >= 10. From about 2.75e5 raw hits across both linear polarizations, none survive the gOTW gating, array-wide simultaneity veto, in-stripe ordering, and single-drift coherence checks, yielding a robust null result. With system equivalent flux density SEFD about 1.5 Jy and an effective 60 s per illuminated crossing, our per-crossing flux density threshold is S_min about 0.50 Jy, corresponding to minimum isotropic-equivalent radiated power EIRP_min in the range (0.72-1.8)e16 W for cluster distances 4-6.5 kpc; when multiple illuminated crossings occur, non-coherent stacking improves sensitivity by up to sqrt(N). To our knowledge this is the first FAST technosignature survey dedicated to globular clusters and the first to use MBPS as the primary observing strategy. These limits disfavor bright, persistent, isotropic L-band beacons above the stated thresholds during our epochs and establish a scalable blueprint, based on geometry-aware gating and verification, for multi-epoch MBPS campaigns that expand signal morphologies and combine passes to deepen constraints on transmitters in dense stellar systems. - oai:arXiv.org:2511.21085v2 - astro-ph.GA + First Resolution of a Main Sequence G-Star Astrosphere Using Chandra + https://arxiv.org/abs/2512.09613 + arXiv:2512.09613v2 Announce Type: replace +Abstract: We report resolution of a halo of X-ray line emission surrounding the Zero Age Main Sequence (ZAMS) G8.5V star HD 61005 by Chandra ACIS-S. Located only 36.4 pc distant, HD 61005 is young (approx. 100 Myr), x-ray bright (300 times Solar), observed with nearly edge-on geometry, and surrounded by Local Interstellar Medium (LISM) material denser than in the environ of the Sun. HD 61005 is known to harbor large amounts of circumstellar dust in a dense ecliptic plane full of mm-sized particles plus attached, extended wing like structures full of micron sized particles, which are evidence for a strong LISM-dust disk interaction. These properties aided our ability to resolve the 220 au wide astrosphere of HD61005, the first ever observed for a main sequence G-star. The observed x-ray emission morphology is roughly spherical, as expected for an astrospheric structure dominated by the host star. The Chandra spectrum of HD 61005 is a combination of a hard stellar coronal emission (T=8 MK) at Lx = 6 x10e29 erg per sec, plus an extended halo contribution at Lx = 1x10e29 erg per sec dominated by charge exchange (CXE) lines, such as those of OVIII and NeIX. The Chandra CXE x-ray morphology does not track the planar dust morphology but does extend out roughly to where the base of the dust wings begins. We present a toy model of x-ray emission produced by stellar wind (SW)-LISM CXE interactions, similar to the state of the young Sun when it was approximately 100 Myrs old (Guinan and Engle 2007), and transiting through an approximately 1000 times denser part of the interstellar medium (ISM) such as a Giant Molecular Cloud (Stern 2003, Opher and Loeb 2024). + oai:arXiv.org:2512.09613v2 astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Bo-Lun Huang, Zhen-Zhao Tao, Tong-Jie Zhang, Vishal Gajjar + http://creativecommons.org/licenses/by/4.0/ + C. M. Lisse, S. J. Wolk, B. Snios, R. L. McNutt, Jr., J. D. Slavin, R. A. Osten, D. C Hines, J. H. Debes, D. Koutroumpa, V. Kharchenko, J. L. Linsky, P. Brandt, M. Horanyi, H. M. Guenther, E. F. Guinan, S. Redfield, P. C. Frisch, K. Dennerl, V. Kashyap, K. G. Kislyakova, Y. R. Fernandez, E. Provornikova, M. A. MacGregor, C. H. Chen, L. Paxton, K. Dialynas, L. Gu - Resolving Interchange Reconnection Dynamics in a Fan-Spine-like Topology Observed by Solar Orbiter - https://arxiv.org/abs/2512.01209 - arXiv:2512.01209v2 Announce Type: replace -Abstract: Interchange reconnection is believed to play a significant role in the production of solar jets and solar wind. However, the dynamics of interchange reconnection in the low corona might be more complex than recognized before in higher temporal and spatial resolutions. Using unprecedentedly high-resolution observations from the Extreme Ultraviolet Imager (EUI) onboard the Solar Orbiter, we analyze the dynamics of interchange reconnection in a small-scale fan-spine-like topology. Interchange reconnection that continuously occurs around the multi-null points of the fan-spine-like system exhibits a quasi-periodicity of ~200 s, nearly covering the entire evolution of this system. Continuous evolution and reversal of multiple current sheets are observed over time near the null point. These results reveal that the dynamics of interchange reconnection are likely modulated by the emerging magnetic structures, such as mini-filaments and emerging arcades. Moreover, a curtain-like feature with a width of 1.7 Mm is also observed near the interchange reconnection region and persistently generates outflows, which is similar to the separatrix curtain reported in the pseudo-streamer structure. This study not only demonstrates the complex and variable reconnection dynamics of interchange reconnection within small-scale fan-spine topology but also provides insights into the self-similarity of magnetic field configurations across multiple temporal and spatial scales. - oai:arXiv.org:2512.01209v2 + Stellar properties and chemical features of the Gaia Catalogue of Nearby Stars observed by GALAH DR4 + https://arxiv.org/abs/2512.10037 + arXiv:2512.10037v2 Announce Type: replace +Abstract: The Gaia Catalogue of Nearby Stars (GCNS) comprises approximately 330 000 stars within 100 pc of the Sun, as observed by Gaia data release 3 (Gaia DR3). Meanwhile, the GALAH DR4 survey has spectroscopically characterised nearly one million stars, delivering detailed chemical abundances (up to 30 elements). We present a joint analysis of the $\sim$ 6 000 stars common to both catalogues, offering initial insights into the stellar and chemical properties of the solar neighborhood. Our preliminary results indicate that the majority of these stars are FGK main-sequence objects, with some A-type interlopers (with effective temperatures ranging between 3 000 and 8 000 K), with median ages of $\sim$ 1.6 Gyr (ranging from 0.10 to 14.79 Gyr), and metal-poorer when compared to the Sun: [Fe/H] $\approx$ -0.19 dex. Additionally, most of the stars are disc members, with some local halo (high-velocity) stars identified. Building on this foundation, future work will deeper exploit the full spectroscopic information and orbital parameters from value-added catalogues to refine Galactic component classifications (thin-thick disc versus halo membership), perform detailed chemical profiling, and deliver a comprehensive chemo-dynamical characterisation of the solar neighborhood. This will provide new insights into the formation and evolution of nearby stellar populations. + oai:arXiv.org:2512.10037v2 astro-ph.SR - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Yadan Duan, Xiaoli Yan, Junchao Hong, Hechao Chen, Yuhang Gao, Zheng Sun, Zhenyong Hou, Jincheng Wang + http://creativecommons.org/licenses/by-nc-sa/4.0/ + P. H. R. de Andrade, M. L. L. Dantas, A. C. Soja - Interstellar Medium in Extremely High Star-Formation Regions: A Prospect of Observations on the Millimetron Space Observatory - https://arxiv.org/abs/2512.07565 - arXiv:2512.07565v2 Announce Type: replace -Abstract: High star-formation rate and active galactic nucleus' emission can significantly transform the interstellar medium. In ultra-luminous infrared galaxies, in which the star-formation rate reaches thousands of solar masses per year, the gas and dust are considerably affected by the ionizing radiation, cosmic rays and shock waves, that can be about a factor of 100--1000 larger than typical values in quiet star-forming galaxies. In these conditions, the emissivity of the gas and dust changes: in dense gas, high ionic and molecular transitions become excited, while dust grains are heated to high temperatures. In this paper, we analyze the possibilities for studying the interstellar medium in extreme conditions of ultra-luminous infrared galaxies at redshifts of $\sim 0-3$, utilizing the atomic and molecular lines, and dust continuum in far infrared range of $100-500\mu$m. We discuss the prospect of observations using the instruments of the Millimetron Space Observatory. - oai:arXiv.org:2512.07565v2 + Super-resolving Herschel - a deep learning based deconvolution and denoising technique + https://arxiv.org/abs/2512.13353 + arXiv:2512.13353v2 Announce Type: replace +Abstract: Dusty star-forming galaxies (DSFGs) dominate the far-infrared and sub-millimetre number counts, but single-dish surveys suffer from poor angular resolution, complicating mult-wavelength counterpart identification. Prior-driven deblending techniques require extensive fine-tuning and struggle to process large fields. This work aims to develop a fast, reliable deep-learning based deconvolution and denoising super-resolution (SR) technique. We employ a transformer neural network to improve the resolution of Herschel/SPIRE 500 $\mu$m observations by a factor 4.5, using Spitzer/MIPS 24$\mu$m and Herschel/SPIRE 250, 350, 500$\mu$m images. Trained on SIDES and SHARK simulations, we injected instrumental noise into the input simulated images, while keeping the target images noise-free to enhance de-noising capabilities of our method. + We evaluated the performance on simulated test sets and real JCMT/SCUBA-2 450 $\mu$m observations in the COSMOS field which have superior resolution compared to Herschel. Our SR method achieves an inference time of $1s/deg^2$ on consumer GPUs, much faster than traditional deblending techniques. Using the simulation test sets, we show that fluxes of the extracted sources from the super-resolved image are accurate to within 5% for sources with an intrinsic flux $\gtrsim$ 8 mJy, which is a substantial improvement compared to blind extraction on the native images. Astrometric error is low ($\lesssim$ 1" vs 12" pixel scale). Reliability is $\gtrsim$ 90% for sources $>$3 mJy and $>$90% of sources with intrinsic fluxes $\gtrsim5$ mJy are recovered. Applied to real 500 $\mu$m observations, fluxes of the extracted sources from the super-resolved map agree well with SCUBA-2 measured fluxes for sources $\geq$10 mJy. Our technique enables SR over hundreds of $deg^2$ without the need for fine-tuning, facilitating statistical analysis of DSFGs. + oai:arXiv.org:2512.13353v2 astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1134/S1063772925702154 - Astronomy Reports, v. 69, pp. 913-929 (2025) - E. O. Vasiliev, S. A. Drozdov, P. V. Baklanov, O. P. Vorobyov, S. Yu. Dedikov, M. S. Kirsanova, T. I. Larchenkova, N. N. Shakhvorostova + Dennis Koopmans, Lingyu Wang, Berta Margalef-Bentabol, Antonio La Marca, Matthieu Bethermin, Laura Bisigello, Zhen-Kai Gao, Claudia del P. Lagos, Lynge Lauritsen, Stephen Serjeant, F. F. S. van der Tak, Wei-Hao Wang - The Milky Way Imaging Scroll Painting Survey: Data Release 1 - https://arxiv.org/abs/2512.08260 - arXiv:2512.08260v2 Announce Type: replace -Abstract: We present the first data release (DR1) of the Milky Way Imaging Scroll Painting (MWISP) survey, a mapping in the J=(1-0) transition lines of 12CO, 13CO, and C18O toward the northern Galactic plane during 2011-2022. The MWISP survey was conducted using the PMO 13.7 m telescope at a spatial resolution of approximately 50" and a velocity resolution of 0.16 km/s at 115 GHz. DR1 fully covered 2310 square degrees within the Galactic longitude (l) and latitude (b) range of 9.75 deg =< l =< 229.75 deg and |b| =< 5.25 deg. The surveyed area was divided into cell units of 30'x30' for practical purposes and On-The-Fly (OTF) mapping was performed toward each target cell unit. The data were regridded into a regular 3D datacube in l-b-V_LSR with a pixel size of 30" in l-b axes and 0.16 km/s in theV_LSR axis. The median rms noise is 0.47 K, 0.25 K, and 0.25 K for 12CO, 13CO, and C18O, respectively. The equivalent 3 sigma sensitivity in 12CO luminosity is approximately 0.23 K km/s, making MWISP the most sensitive survey of its kind. In this paper, we describe the survey data, including the calibration, data cleaning, data mosaic processes, and the data products. The final mosaicked data cubes contain about 3.33x10^7 spectra (pixels) for each CO isotopologue line. Color composite images, made from the intensities of the isotopologue lines, and some concise descriptions are provided. We constructed a molecular cloud catalog based on the mosaicked 12CO data cube using the clustering algorithm DBSCAN, detecting 103,517 molecular clouds, 10,790 of which exhibit 13CO emission and 304 of which show C18O emission. Based on the histogram of voxel brightness temperature, we estimated a total 12CO flux of 7.69+/-0.38x10^7 K km/s arcmin^2, 82% of which is captured by the DBSCAN algorithm. The data, together with the cloud sample, provide unique information on molecular gas in the northern Milky Way. - oai:arXiv.org:2512.08260v2 + From ASTRID to BRAHMA -- The role of overmassive black holes in little red dots in cosmological simulations + https://arxiv.org/abs/2512.13957 + arXiv:2512.13957v2 Announce Type: replace +Abstract: We leverage the overmassive black holes ($\rm M_{BH}/M_{\ast} \approx0.1$) present in a realization of the BRAHMA cosmological hydrodynamic simulation suite to investigate their role in the emission of the unique ``little red dot'' (LRD) objects identified by the James Webb Space Telescope (JWST). We find that these black holes can produce LRD-like observables when their emission is modeled with a dense gas cloud shrouding the active galactic nucleus (AGN). Between redshifts 5 and 8, we find the number density of LRDs in this simulation to be $\rm 2.04 \pm 0.32 \times 10^{-4} \space Mpc^{-3}$, which is broadly consistent with current estimates for the total LRD population from JWST. Their emission in the rest-frame visible spectrum is dominated by their AGN, which induces the red color indicative of LRDs via a very strong Balmer break. Additionally, the elevated mass of the black holes reduces the temperature of their accretion discs. This shifts the peak of the AGN emission towards longer wavelengths, and increases their brightness in the rest-frame visible spectrum relative to lower mass black holes accreting at the same rate. These simulated LRDs have very minimal dust attenuation ($\rm A_V = 0.21 \pm 0.12$), limiting the amount of dust re-emission that would occur in the infrared, making them very likely to fall below the observed detection limits from observatories like the Atacama Large Millimeter Array (ALMA). In contrast to the BRAHMA box, the ASTRID simulation produces systematically smaller black holes and predicts LRD number densities that are more than two orders of magnitude lower than current measurements. We therefore conclude that the presence of black holes that are overmassive relative to their host galaxy, and enshrouded in dense gas, is necessary for AGN-dominated LRD models to reproduce both the observed properties and abundances of JWST LRD populations. + oai:arXiv.org:2512.13957v2 astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Ji Yang (Qinghai), Qing-Zeng Yan (Qinghai), Yang Su (Qinghai), Shaobo Zhang (Qinghai), Xin Zhou (Qinghai), Yan Sun (Qinghai), Yiping Ao (Qinghai), Xuepeng Chen (Qinghai), Zhiwei Chen (Qinghai), Fujun Du (Qinghai), Min Fang (Qinghai), Yan Gong (Qinghai), Zhibo Jiang (Qinghai), Shengyu Jin (Qinghai), Binggang Ju (Qinghai), Chong Li (Qinghai), Yingjie Li (Qinghai), Yi Liu (Qinghai), Dengrong Lu (Qinghai), Chunsheng Luo (Qinghai), Yuehui Ma (Qinghai), Ruiqing Mao (Qinghai), Jixian Sun (Qinghai), Chen Wang (Qinghai), Hongchi Wang (Qinghai), Min Wang (Qinghai), Min Wang (Qinghai), Xindong Wang, Wenting Xu, Ye Xu, Kun Yan, Ping Yan, Lixia Yuan, Miaomiao Zhang, Yongxing Zhang + Patrick LaChance, Aklant Kumar Bhowmick, Rupert A. C. Croft, Tiziana Di Matteo, Yihao Zhou, Fabio Pacucci, Laura Blecha, Paul Torrey, Yueying Ni, Nianyi Chen, Simeon Bird - Self-lensing of moving gravitational-wave sources can break the microlensing crossing timescale degeneracy - https://arxiv.org/abs/2512.08898 - arXiv:2512.08898v2 Announce Type: replace -Abstract: When a moving gravitational-wave (GW) source travels behind a massive astrophysical object, its signal is gravitationally lensed, showing a waveform distortion similar to a Paczy\'{n}ski curve. We present a first study of the lensing signature of a massive black hole (MBH) on a frequency-dependent GW signal from a moving binary merger. For both light and GW sources in a Keplerian circular orbit around a MBH lens, the self-lensing geometry breaks the microlensing degeneracy in the Einstein radius crossing timescale $t_{\rm E}$. The duration of the curve ($2 t_{\rm E}$) becomes independent on the MBH mass $M_{\rm MBH}$, and provides a direct measure of the distance $d_{\rm LS}$ to the MBH. However, $M_{\rm MBH}$ remains unknown. We show that, in GW signals, the redshifted mass $M_{{\rm MBH},z}$ can additionally be obtained from the interference pattern, by measuring the modulation period $T$, the GW frequency $f$, and $t_{\rm E}$: $M_{{\rm MBH},z}\simeq 2.5\times 10^6\,M_\odot\,(t_{\rm E}/[100\,{\rm s}])\,(f\,T)^{-1}$. If this lensing signature is not considered, it may be confused with other waveform distortions, especially in the modeling of overlapping signals in next generation ground-based GW detectors. The observation of one of these curves and its associated parameters may help (1) constrain the orbital distance $d_{\rm LS}$ of sources, especially around low-mass MBHs at the center of star clusters and galaxies, (2) additionally estimate the mass $M_{{\rm MBH},z}$ of these MBHs, and (3) infer the orbital inclination of the binary. Simultaneously obtaining $d_{\rm LS}$ and $M_{{\rm MBH},z}$ through self-lensing can help constrain the astrophysical environments where GW signals come from. - oai:arXiv.org:2512.08898v2 - astro-ph.HE - astro-ph.CO - astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Characterisation of the Bedretto Underground Site for Fundamental Physics Experiments + https://arxiv.org/abs/2512.14815 + arXiv:2512.14815v2 Announce Type: replace +Abstract: Underground laboratories provide the ultra-low background and low-vibration environments essential for rare-event searches, gravitational-wave detection, and quantum-sensing technologies. We report a comprehensive environmental characterisation of the Bedretto tunnel in Ticino, Switzerland, a site offering horizontal access, excellent infrastructure, and the potential to be be Europe's second-deepest and quietest underground laboratory. At the prospective physics site, located beneath an overburden exceeding 1400 m, we measure the cosmic-muon, gamma-ray, and neutron fluxes, as well as the radon concentration, magnetic-field spectrum, and seismic backgrounds. The muon flux is suppressed by six orders of magnitude relative to the surface, consistent with an effective depth of about 4000 metre water equivalent, gamma-ray and neutron measurements reflect the local geology and guide shielding requirements for future particle and nuclear physics experiments. Magnetic and seismic noise levels are found to be exceptionally low, meeting or exceeding the criteria for next-generation atom-interferometric gravitational-wave detectors. These results establish the site as a highly competitive, accessible deep-underground location for fundamental-physics experiments. + oai:arXiv.org:2512.14815v2 + astro-ph.IM + hep-ex + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Helena Ubach + http://creativecommons.org/licenses/by/4.0/ + Bj\"orn Penning, Nicolas Angelides, Laura Baudis, Harvey Birch, Abigail Flowers, Florian J\"org, Alexander Kavner, Marcelle Soares-Santos, Aravind Sreekala, Johannes W\"uthrich, Guandi Zhao, Chiara Capelli, John Clinton, Jose Cuenca Garc\'ia, Paolo Crivelli, Domenico Giardini, Evangelos-Leonidas Gkougkousis, Yacine Haddad, Marian Hertrich, Rebecca Hochreutener, Luisa H\"otzsch, Philippe Jetzer, Ben Kilminster, Boris Korzh, Frederick Massin, Knut Dundas Mor{\aa}, Margherita Noia, Francesco Piastra, Christian Regenfus, Federico Sanchez, Steven Schramm, Francesco Riva, Serhan Tufanli, Michele Weber, Stefan Wiemer, Mathilde Wimez - The impact of AGN environmental effects on testing general relativity with space-borne gravitational wave detector - https://arxiv.org/abs/2512.09635 - arXiv:2512.09635v2 Announce Type: replace -Abstract: The space-borne gravitational wave detectors such as TianQin offers a new window to test General Relativity by observing the early inspiral phase of stellar-mass binary black holes. A key concern arises if these stellar-mass binary black holes reside in gaseous environments such as active galactic nucleus accretion disks, where environmental effects imprint detectable modulations on the gravita- tional waveform. Using Bayesian inference on simulated signals containing both environmental and dipole deviation, we have assessed the extent to which the presence of environmental effects affects the detectability of dipole radiation. Our results demonstrate that even in the presence of strong environmental coupling, the dipole parameter can be recovered with high precision, and the evidence for dipole radiation remains distinguishable. Crucially, we find that the existence of environmental effects does not fundamentally impede the identification of dipole radiation, provided both effects are simultaneously modelled in the inference process. This study establishes that future tests of modified gravity with space-borne observatories can remain robust even for sources in astrophysical environments. - oai:arXiv.org:2512.09635v2 - astro-ph.HE - gr-qc - Fri, 12 Dec 2025 00:00:00 -0500 + Stellar Morphology of Optically Dark or Faint Galaxies at $z>3$ with JWST + https://arxiv.org/abs/2512.15127 + arXiv:2512.15127v2 Announce Type: replace +Abstract: JWST offers an unprecedented view of optically dark or faint galaxies (OFGs), previously missed by HST. They are likely massive, heavily dust-obscured star-forming galaxies (SFGs) that substantially contribute to the cosmic SFR density at $z>$3. To identify drivers of their high dust attenuation and their role in early universe galaxy evolution, we analyse the stellar morphology of 65 OFGs (from 1892 SFGs at 3$<z<$4) using NIRCam/F444W imaging from the PRIMER and CEERS fields. We study correlations between dust attenuation ($A_v$) and galaxy properties, like stellar mass, size, and orientation, and compare scaling relations between OFGs and typical SFGs. We find that OFGs are ~8-9 times more massive and ~4 times more dust attenuated than the parent sample. Structurally, OFGs resemble parent SFGs in median $R_e$ and median $\Sigma_{R_e}$ but may be slightly rounder on average. While $A_v$ strongly correlates with stellar mass, it does not show significant dependence on stellar mass-normalised effective radius and stellar mass surface density, S\'ersic index, axis ratio, or SFR surface density. The mass-size and mass-surface density relations place OFGs as a higher-mass extension of SFGs, with no concrete proof of evolutionary differences between them. This suggests that OFGs are heavily dust-obscured primarily due to their high stellar masses, which facilitates dust production and retention, with older stellar populations likely contributing as well. Although some OFGs exhibit high $\Sigma_\mathrm{{R_e}}$ and occupy regions of the mass-size plane similar to quiescent galaxies, the overall sample is not representative of this. Their current structures resemble typical SFGs, with no concrete signs of rapid compaction. Diversity in their physical properties shows that OFGs span a range of evolutionary states with few showing reduced star formation, while most remain actively star-forming. + oai:arXiv.org:2512.15127v2 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Xiangyu Lyu, Hongyu Chen, En-Kun Li, Yi-Ming Hu + Arpita Ganguly, Mengyuan Xiao, Pascal A. Oesch, Miroslava Dessauges-Zavadsky, Andrea Weibel, Natalie Allen, Longji Bing, Sarah Bosman, Gabriel Brammer, David Elbaz, Emanuele Daddi, Benjamin Magnelli, Tim B. Miller, Maxime Tarrasse - Massive Star Clusters as sources of high-energy gamma radiation - https://arxiv.org/abs/2512.09743 - arXiv:2512.09743v2 Announce Type: replace -Abstract: This paper investigates the contribution of massive star clusters (MSC) as sources of high-energy gamma rays and their impact on the ultra-high-energy (UHE) emission observed throughout the Galaxy. By modeling proton injection, the study explores how the acceleration of protons in massive star clusters contributes to the gamma radiation detectable from Earth. The analysis focuses on two primary types of clusters: widespread, dispersed clusters and younger, compact massive clusters, both of which host shock waves generated by supernova remnants (SNR). Clusters located near the solar system, within a 3-kiloparsec radius,are identified. Analytical methods are used to calculate energy spectra and gamma-ray production rates. The findings suggest that young and compact MSC contribute to multi-TeV to PeV gamma-ray emission, with the dominant contribution arising from nearby populations. - oai:arXiv.org:2512.09743v2 - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + Dual-coding contrastive learning based on ConvNeXt and ViT models for morphological classification of galaxies in COSMOS-Web + https://arxiv.org/abs/2512.15129 + arXiv:2512.15129v2 Announce Type: replace +Abstract: In our previous works, we proposed a machine learning framework named \texttt{USmorph} for efficiently classifying galaxy morphology. In this study, we propose a self-supervised method called contrastive learning to upgrade the unsupervised machine learning (UML) part of the \texttt{USmorph} framework, aiming to improve the efficiency of feature extraction in this step. The upgraded UML method primarily consists of the following three aspects. (1) We employ a Convolutional Autoencoder to denoise galaxy images and the Adaptive Polar Coordinate Transformation to enhance the model's rotational invariance. (2) A pre-trained dual-encoder convolutional neural network based on ConvNeXt and ViT is used to encode the image data, while contrastive learning is then applied to reduce the dimension of the features. (3) We adopt a Bagging-based clustering model to cluster galaxies with similar features into distinct groups. By carefully dividing the redshift bins, we apply this model to the rest-frame optical images of galaxies in the COSMOS-Web field within the redshift range of $0.5 < z < 6.0$. Compared to the previous algorithm, the improved UML method successfully classifies 73\% galaxies. Using the GoogleNet algorithm, we classify the morphology of the remaining 27\% galaxies. To validate the reliability of our updated algorithm, we compared our classification results with other galaxy morphological parameters and found a good consistency with galaxy evolution. Benefiting from its higher efficiency, this updated algorithm is well-suited for application in future China Space Station Telescope missions. + oai:arXiv.org:2512.15129v2 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Luana N. Padilha, Rita C. Anjos + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + ApJS (2025), 278 39 + Shiwei Zhu, Guanwen Fang, Chichun Zhou, Jie Song, Zesen Lin, Yao Dai, Xu Kong - Clumpy, dense gas in the outflow of NGC 1266 - https://arxiv.org/abs/2512.09889 - arXiv:2512.09889v2 Announce Type: replace -Abstract: Outflows are one of the most spectacular mechanisms through which active galactic nuclei (AGN) impact their host galaxy, though the role of AGN-driven outflows in global star formation regulation across the galaxy population is unclear. NGC 1266 is an excellent case study for investigating the outflows and star formation quenching because it is a nearby (D\sim30 Mpc) AGN host galaxy with an outflow driving shocks through the interstellar medium (ISM) and has recently quenched its star formation outside the nucleus. While previous works have studied the molecular outflow from its CO emission, to fully characterize the impact the outflow has on the ISM observations probing the dense, cold gas are necessary. Our ALMA cycle 0 observations do not detect a molecular outflow in 13CO(2-1) and yield a lower limit 12CO/13CO \geq 250, suggesting a highly optically thin CO outflow with low 13CO abundance. In contrast, we detect substantial HCN(1-0) emission in the outflow, with an HCN(1-0)/12CO(1-0) ratio of 0.09, consistent with global measurements of many star-forming galaxies and Luminous InfraRed Galaxies (LIRGs). We conclude that the CO emission traces a diffuse component of the molecular gas with a low optical depth, whereas the HCN(1-0) traces dense clumps of gas entrained in the outflow. We measure an upper limit molecular outflow rate of < 85 Msun/yr. Assuming the ongoing nuclear star formation and outflow continue at the same rates, NGC 1266 will deplete its gas reservoirs in 450 Myr or longer, indicating that relatively low-level AGN feedback is capable of gradually expelling the molecular gas reservoir after a rapid quenching event. - oai:arXiv.org:2512.09889v2 + An updated efficient galaxy morphology classification model based on ConvNeXt encoding with UMAP dimensionality reduction + https://arxiv.org/abs/2512.15137 + arXiv:2512.15137v2 Announce Type: replace +Abstract: We present an enhanced unsupervised machine learning (UML) module within our previous \texttt{USmorph} classification framework featuring two components: (1) hierarchical feature extraction via a pre-trained ConvNeXt convolutional neural network (CNN) with transfer learning, and (2) nonlinear manifold learning using Uniform Manifold Approximation and Projection (UMAP) for topology-aware dimensionality reduction. This dual-stage design enables efficient knowledge transfer from large-scale visual datasets while preserving morphological pattern geometry through UMAP's neighborhood preservation. We apply the upgraded UML on I-band images of 99,806 COSMOS galaxies at redshift $0.2<z<1.2$ (to ensure rest-frame optical morphology) with $I_{\mathrm{mag}}<25$. The predefined cluster number is optimized to 20 (reduced from 50 in the original framework), achieving significant computational savings. The 20 algorithmically identified clusters are merged into five physical morphology types. About 51\% of galaxies (50,056) were successfully classified. To assess classification effectiveness, we tested morphological parameters for massive galaxies with $M_{*}>10^{9}~M_{\odot}$. Our classification results align well with galaxy evolution theory. This improved algorithm significantly enhances galaxy morphology classification efficiency, making it suitable for large-scale sky surveys such as those planned with the China Space Station Telescope (CSST). + oai:arXiv.org:2512.15137v2 astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 + Fri, 19 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Justin Atsushi Otter, Katherine Alatalo, Kate Rowlands, Pallavi Patil, Maya Skarbinski, Lauren Dysarz, Mark Lacy, Maria J. Jimenez-Donaire, Susanne Aalto, Timothy A. Davis, Antoniu Fodor, K. Decker French, Nanase Harada, Timothy Heckman, Ryo Kishikawa, Sebastian Lopez, Yuanze Luo, Sergio Martin, Anne M. Medling, Kristina Nyland, Andreea Petric, Namrata Roy, Mamiko Sato, Elizaveta Sazonova, Adam Smercina, Akshat Tripathi + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Guanwen Fang, Shiwei Zhu, Jun Xu, Shiying Lu, Chichun Zhou, Yao Dai, Zesen Lin, Xu Kong - Testing models for angular power spectra: A distribution-free approach - https://arxiv.org/abs/2504.16079 - arXiv:2504.16079v5 Announce Type: replace-cross -Abstract: A novel goodness-of-fit strategy is introduced for testing models of angular power spectra with unknown parameters. Using this strategy, it is possible to assess the validity of such models without specifying the distribution of the angular power spectrum estimators. This holds under general conditions, ensuring the method's applicability in diverse applications. Moreover, the proposed solution overcomes the need for case-by-case simulations when testing different models, leading to notable computational advantages. - oai:arXiv.org:2504.16079v5 - physics.data-an - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - Sara Algeri, Xiangyu Zhang, Erik Floden, Hongru Zhao, Galin L. Jones, Vuk Mandic, Jesse Miller + Robustness Analysis of USmorph: I. Generalization Efficiency of Unsupervised Strategies and Supervised Learning in Galaxy Morphological Classification + https://arxiv.org/abs/2512.15142 + arXiv:2512.15142v2 Announce Type: replace +Abstract: We conduct a systematic robustness analysis of the hybrid machine learning framework \texttt{USmorph}, which integrates unsupervised and supervised learning for galaxy morphological classification. Although \texttt{USmorph} has already been applied to nearly 100,000 $I$-band galaxy images in the COSMOS field ($0.2 < z < 1.2$, $I_{\mathrm{mag}} < 25$), the stability of its core modules has not been quantitatively assessed. Our tests show that the convolutional autoencoder (CAE) achieves the best performance in preserving structural information when adopting an intermediate network depth, $5\times5$ convolutional kernels, and a 40-dimensional latent representation. The adaptive polar coordinate transform (APCT) effectively enhances rotational invariance and improves the robustness of downstream tasks. In the unsupervised stage, a bagging clustering number of $K=50$ provides the optimal trade-off between classification granularity and labeling efficiency. For supervised learning, we employ GoogLeNet, which exhibits stable performance without overfitting. We validate the reliability of the final classifications through two independent tests: (1) the t-distributed stochastic neighbor embedding (t-SNE) visualization reveals clear clustering boundaries in the low-dimensional space; and (2) the morphological classifications are consistent with theoretical expectations of galaxy evolution, with both true and false positives showing unbiased distributions in the parameter space. These results demonstrate the strong robustness of the \texttt{USmorph} algorithm, providing guidance for its future application to the China Space Station Telescope (CSST) mission. + oai:arXiv.org:2512.15142v2 + astro-ph.GA + Fri, 19 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + ApJ (2025), 995 168 + Shiwei Zhu, Guanwen Fang, Yao Dai, Chichun Zhou, Yirui Zheng, Jie Song, Shiying Lu, Xu Kong - Angular momentum of vacuum bubbles in a first-order phase transition - https://arxiv.org/abs/2505.09202 - arXiv:2505.09202v2 Announce Type: replace-cross -Abstract: The formation of primordial black holes (PBHs) during a first-order phase transition (FOPT) in a dark sector has been of recent interest. A quantity that characterizes a black hole is its spin. We carry out the first step towards determining the spin of such PBHs, by calculating the spin of spherical false vacuum bubbles induced by cosmological perturbations. The angular momentum is given by the product of density and velocity perturbations. We carefully track the evolution of background quantities and calculate the transfer functions during the FOPT. We find that the dimensionless spin parameter $s = J/(G_{\rm N} M^2)$ of false vacuum bubbles of mass $M$ and angular momentum $J$, take a wide range of values from ${\cal{O}}(10^{-5})$ to ${\cal{O}}(10)$ for FOPTs between 10 keV and 100 GeV and a dark sector that is 0.1 to 0.4 times cooler than the visible sector. We also find a scaling relation between the root-mean-square value of the spin, the FOPT time scale, the bubble wall velocity, and the dark sector-to-visible sector temperature ratio. - oai:arXiv.org:2505.09202v2 - hep-ph + Ultralight Dark Matter Constraints from NanoHertz Gravitational Waves + https://arxiv.org/abs/2512.15292 + arXiv:2512.15292v2 Announce Type: replace +Abstract: We investigate the impact of ultralight dark matter (ULDM) on the mergers of supermassive black holes (SMBH) and the resulting stochastic gravitational wave background. ULDM is based on exceptionally light particles and yields galactic halos with dense central solitons. This increases the drag experienced by binary SMBH, decreasing merger times and potentially suppressing gravitational radiation from the binary at low frequencies. We develop semi-analytic models for the decay of SMBH binaries in ULDM halos and use current pulsar timing array (PTA) measurements to constrain the ULDM particle mass and its fractional contribution to the dark matter content of the universe. We find a median ULDM particle mass of $7. \times 10^{-22}$ eV and show that scaling relations suggest that the drag remains effective at relatively low ULDM fractions, which are consistent with all other constraints on the model. Consequently, future pulsar timing measurements will be a sensitive probe of any ULDM contribution to the overall dark matter content of the universe. + oai:arXiv.org:2512.15292v2 astro-ph.CO - hep-ex - Fri, 12 Dec 2025 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - Jan Tristram Acu\~na, Danny Marfatia, Po-Yan Tseng - - - Modelling cosmic-ray transport: magnetised versus unmagnetised motion in astrophysical magnetic turbulence - https://arxiv.org/abs/2505.18155 - arXiv:2505.18155v3 Announce Type: replace-cross -Abstract: Cosmic-ray transport in turbulent astrophysical environments remains a multifaceted problem and, despite decades of study, the impact of complex magnetic field geometry -- evident in simulations and observations -- has only recently received more focussed attention. To understand how ensemble-averaged transport behaviour emerges from the intricate interactions between cosmic rays and structured magnetic turbulence, we run test-particle experiments in snapshots of a strongly turbulent magnetohydrodynamics simulation. We characterise particle--turbulence interactions via the gyro radii of particles and their experienced field-line curvatures, which reveals two distinct transport modes: magnetised motion, where particles are tightly bound to strong coherent flux tubes and undergo large-scale mirroring; and unmagnetised motion, characterised by chaotic scattering through weak and highly tangled regions of the magnetic field. We formulate an effective stochastic process for each mode: compound subdiffusion with long mean free paths for magnetised motion, and a Langevin process with short mean free paths for unmagnetised motion. A combined stochastic walker that alternates between these two modes accurately reproduces the mean squared displacements observed in the test-particle data. Our results emphasise the critical role of coherent magnetic structures in comprehensively understanding cosmic-ray transport and lay a foundation for developing a theory of geometry-mediated transport. - oai:arXiv.org:2505.18155v3 - physics.plasm-ph - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - 10.1017/S0022377825100883 - Jeremiah L\"ubke, Patrick Reichherzer, Sophie Aerdker, Frederic Effenberger, Mike Wilbert, Horst Fichtner, Rainer Grauer - - - Black Hole Thermodynamics: Established Results, Unresolved Paradoxes, and Speculative Resolutions - https://arxiv.org/abs/2507.03778 - arXiv:2507.03778v2 Announce Type: replace-cross -Abstract: Between 1972 and 1975, Jacob Bekenstein proposed that black holes possess entropy proportional to their horizon area, and Stephen Hawking derived this relationship from semiclassical quantum field theory in curved spacetime, predicting thermal radiation from black holes. These developments established black hole thermodynamics as a formal framework connecting general relativity, quantum mechanics, and statistical physics. However, this synthesis rests on approximations whose validity remains unproven in regimes where quantum gravitational effects become important. This article provides a detailed overview of the historical development from 1972 to 1975 and surveys modern proposals, such as the holographic principle and gravitational path integrals. We highlight persistent theoretical challenges, including the information paradox, the trans-Planckian problem, backreaction effects, and the absence of experimental verification. The work concludes by identifying which aspects of black hole thermodynamics are well-established and which remain speculative or fundamentally incomplete. - oai:arXiv.org:2507.03778v2 - gr-qc - astro-ph.GA - Fri, 12 Dec 2025 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Ricardo Bulc\~ao Valente Ferrari, Samuel Bueno Soltau + Fri, 19 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Shreyas Tiruvaskar, Russell Boey, Richard Easther, Chris Gordon - Trustworthy scientific inference with generative models - https://arxiv.org/abs/2508.02602 - arXiv:2508.02602v2 Announce Type: replace-cross -Abstract: Generative artificial intelligence (AI) excels at producing complex data structures (text, images, videos) by learning patterns from training examples. Across scientific disciplines, researchers are now applying generative models to "inverse problems" to directly predict hidden parameters from observed data along with measures of uncertainty. While these predictive or posterior-based methods can handle intractable likelihoods and large-scale studies, they can also produce biased or overconfident conclusions even without model misspecifications. We present a solution with Frequentist-Bayes (FreB), a mathematically rigorous protocol that reshapes AI-generated posterior probability distributions into (locally valid) confidence regions that consistently include true parameters with the expected probability, while achieving minimum size when training and target data align. We demonstrate FreB's effectiveness by tackling diverse case studies in the physical sciences: identifying unknown sources under dataset shift, reconciling competing theoretical models, and mitigating selection bias and systematics in observational studies. By providing validity guarantees with interpretable diagnostics, FreB enables trustworthy scientific inference across fields where direct likelihood evaluation remains impossible or prohibitively expensive. - oai:arXiv.org:2508.02602v2 - stat.ML - astro-ph.IM - cs.LG - stat.AP - stat.ME - Fri, 12 Dec 2025 00:00:00 -0500 - replace-cross + JWST NIRSpec finds no clear signs of an atmosphere on TOI-1685 b + https://arxiv.org/abs/2512.15338 + arXiv:2512.15338v2 Announce Type: replace +Abstract: Determining the prevalence of atmospheres on terrestrial planets is a core objective in exoplanetary science. While M dwarf systems offer a promising opportunity, conclusive observations of terrestrial atmospheres have remained elusive, with many yielding flat transmission spectra. We observe four transits of the hot terrestrial planet TOI-1685 b using JWST's NIRSpec G395H instrument. Combining this with the transit from the previously-observed phase curve of the planet with the same instrument, we perform a detailed analysis to determine the possibility of an atmosphere on TOI-1685 b. From our retrievals, the Bayesian evidence favours a simple flat line model, indicating no evidence for an atmosphere on TOI-1685 b, in line with results from the phase curve analysis. Our results show that hydrogen-dominated atmospheres can be confidently ruled out. For heavier, secondary atmospheres we find a lower limit on the mean molecular weight of ~10, at a significance of ~5 sigma. Pure CO2, SO2, H2O, and CH4 atmospheres, or a mixed secondary atmosphere (CO+CO2+SO2) could explain the data (Delta lnZ < 3). However, pure CH4 atmospheres may be physically unlikely, and the pure H2O and CO2 cases require a high-altitude cloud, which could also be interpreted as a thin cloud-free atmosphere. We discuss the theoretical possibility for different types of atmosphere on this planet, and consider the effects of atmospheric escape and stellar activity on the system. Though we find that TOI-1685 b is likely a bare rock, this study also highlights the challenges of detecting secondary atmospheres on rocky planets with JWST. + oai:arXiv.org:2512.15338v2 + astro-ph.EP + Fri, 19 Dec 2025 00:00:00 -0500 + replace http://creativecommons.org/licenses/by/4.0/ - James Carzon, Luca Masserano, Joshua D. Ingram, Alex Shen, Antonio Carlos Herling Ribeiro Junior, Tommaso Dorigo, Michele Doro, Joshua S. Speagle, Rafael Izbicki, Ann B. Lee + Chloe E. Fisher, Matthew J. Hooton, Am\'elie Gressier, Merlin Zgraggen, Meng Tian, Kevin Heng, Natalie H. Allen, Richard D. Chatterjee, Brett M. Morris, Nicholas W. Borsato, N\'estor Espinoza, Daniel Kitzmann, Tobias G. Meier, Lars A. Buchhave, Adam J. Burgasser, Brice-Olivier Demory, Mark Fortune, H. Jens Hoeijmakers, Raphael Luque, Erik A. Meier Vald\'es, Jo\~ao M. Mendon\c{c}a, Bibiana Prinoth, Alexander D. Rathcke, Jake Taylor - A Markov Decision Process Framework for Early Maneuver Decisions in Satellite Collision Avoidance - https://arxiv.org/abs/2508.05876 - arXiv:2508.05876v2 Announce Type: replace-cross -Abstract: We develop a Markov decision process (MDP) framework to autonomously make guidance decisions for satellite collision avoidance maneuver (CAM) and a reinforcement learning policy gradient (RL-PG) algorithm to enable direct optimization of guidance policy using historic CAM data. In addition to maintaining acceptable collision risks, this approach seeks to minimize the average propellant consumption of CAMs by making early maneuver decisions. We model CAM as a continuous state, discrete action and finite horizon MDP, where the critical decision is determining when to initiate the maneuver. The MDP models decision rewards using analytical models of collision risk, propellant consumption, and transit orbit geometry. By deciding to maneuver earlier than conventional methods, the Markov policy effectively favors CAMs that achieve comparable rates of collision risk reduction while consuming less propellant. Using historical data of tracked conjunction events, we verify this framework and conduct an extensive parameter-sensitivity study. When evaluated on synthetic conjunction events, the trained policy consumes significantly less propellant overall and per maneuver in comparison to a conventional cut-off policy that initiates maneuvers 24 hours before the time of closest approach (TCA). On historical conjunction events, the trained policy consumes more propellant overall but consumes less propellant per maneuver. For both historical and synthetic conjunction events, the trained policy is slightly more conservative in identifying conjunctions events that warrant CAMs in comparison to cutoff policies. - oai:arXiv.org:2508.05876v2 - cs.LG - astro-ph.EP + Searching potential astronomical sites in Ethiopia + https://arxiv.org/abs/2512.15669 + arXiv:2512.15669v2 Announce Type: replace +Abstract: This work aims to choose potential astronomical sites that can be candidates for a new astronomical optical observatory in Ethiopia, in addition to the Entoto Observatory and Lalibela sites. For our primary investigation, the six basic criteria, namely the altitude of the mountains, artificial light pollution, cloud coverage, humidity, wind speed, and wind direction, are taken into account. Consequently, using the multi-criteria statistical analysis (MCSA) techniques, 21 high-potential places are selected and presented for further investigation out of 367 mountains. Those selected mountains are mapped and presented to study the future of the astronomical seeing effect. This study may contribute to the protection of those potential astronomical sites and their dark skies and the development of astrotourism for the sustainable development of modern astronomy in Ethiopia and in the East African region. + oai:arXiv.org:2512.15669v2 astro-ph.IM - cs.ET - Fri, 12 Dec 2025 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Francesca Ferrara, Lander W. Schillinger Arana, Florian D\"orfler, Sarah H. Q. Li - - - The complementary of CTAO, direct detection and collider searches for dark matter in Effective Field Theories and Simplified models - https://arxiv.org/abs/2509.06628 - arXiv:2509.06628v2 Announce Type: replace-cross -Abstract: This paper explores the sensitivity of the Cherenkov Telescope Array Observatory to dark matter annihilation in the Galactic Center, within the frameworks of Effective Field Theory and Simplified Models. We present sensitivity forecasts, utilizing an up-to-date instrument configuration and incorporating the latest models for Galactic Diffuse Emission. A key aspect of our work is the inclusion of updated dark matter density profiles, J-factors, and velocity dispersion distributions derived from the FIRE-2 cosmological hydrodynamical simulations, which significantly impact the expected indirect detection signals. Furthermore, we update the constraints from direct detection experiments (Xenon1T and LZ) taking into account the astrophysical uncertainties informed by the FIRE-2 simulations, and also investigate limits coming from collider searches (ATLAS and CMS). Our analysis reveals improved constraints on the effective suppression scale ($M_*$) in the Effective Field Theory framework and on the mediator mass ($M_{med}$) in Simplified Models compared to previous studies, highlighting the complementarity of the Cherenkov Telescope Array Observatory with direct and collider searches in probing a wide range of dark matter scenarios. We discuss the implications of these results for various dark matter interaction types, including scalar, pseudoscalar, vector, and axial-vector mediators, and emphasize the importance of considering realistic astrophysical inputs in interpreting dark matter search results across different experimental fronts. - oai:arXiv.org:2509.06628v2 - hep-ph - astro-ph.HE - hep-ex - Fri, 12 Dec 2025 00:00:00 -0500 - replace-cross + Fri, 19 Dec 2025 00:00:00 -0500 + replace http://creativecommons.org/licenses/by/4.0/ - Igor Reis, Andre Scaffidi, Emmanuel Moulin, Martin White + S. Sahlu, N. Suleiman, GM. Kumssa, ST. Belay, E. Alemayehu, M. Getnet, M. Povic, SH. Negu, B. Belata, J. Tamrat - High Energy Particle Production from Proton Synchrotron Radiation in Strong Magnetic Fields in Relativistic Quantum Field Theory - https://arxiv.org/abs/2509.24366 - arXiv:2509.24366v3 Announce Type: replace-cross -Abstract: We investigate photon, pion, and rho-meson production from proton synchrotron radiation in the presence of strong magnetic fields. The proton decay widths and the luminosities of the emitted particles are calculated within a relativistic quantum framework that incorporates Landau quantization. A scaling rule is derived for the transition probability between different Landau levels. This allows an evaluation of transitions for extremely high Landau numbers exceeding $10^{15}$. Furthermore, we calculate the momentum distribution of the emitted particles by properly including the proton recoil effect associated with particle emission. The results differ significantly from conventional semiclassical approaches. - oai:arXiv.org:2509.24366v3 + Numerical simulations of density perturbation and gravitational wave production from cosmological first-order phase transition + https://arxiv.org/abs/2502.20166 + arXiv:2502.20166v2 Announce Type: replace-cross +Abstract: We conducted three-dimensional lattice simulations to study the density perturbation and gravitational waves (GWs) during first-order phase transition (FOPT). We find that for phase transition strength $\alpha > 1$, the forward motion of bubble walls becomes the primary source, whereas for $\alpha < 1$, the dominant contribution to the density perturbation comes from the delay of vacuum decay. Additionally, the power spectrum of density perturbations generated by the phase transition exhibits a slope of $k^3$ at small wavenumbers and $k^{-1.5}$ at large wavenumbers. Furthermore, we calculated the GW power spectra, which exhibit the slope of $k^3$ at small wavenumbers and $k^{-2}$ at large wavenumbers. Our numerical simulations confirm that slow PTs can produce PBHs and provide predictions for the GW power spectrum, offering theoretical support for GW detection. + oai:arXiv.org:2502.20166v2 hep-ph - astro-ph.HE - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.CO + hep-th + Fri, 19 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Tomoyuki Maruyama, A. Baha Balantekin, Myung-Ki Cheoun, Akira Dohi, Ryo Higuch, Toshitaka Kajino, Grant J. Mathews + Jintao Zou, Zhiqing Zhu, Zizhuo Zhao, Ligong Bian - Restrictions on Initial Conditions in Cosmological Scenarios and Implications for Simulations of Primordial Black Holes and Inflation - https://arxiv.org/abs/2509.26470 - arXiv:2509.26470v2 Announce Type: replace-cross -Abstract: Numerical relativity simulations provide a means by which to study the evolution and end point of strong over-densities in cosmological spacetimes. Specific applications include studies of primordial black hole formation and the robustness of inflation. Here we adopt a toy model previously used in asymptotically flat spacetimes to show that, for given values of the over-density and the mean curvature, solutions to the Hamiltonian constraint need not exist, and if they do exist they are not unique. Specifically, pairs of solutions exist on two branches, corresponding to strong-field and weak-field solutions, that join at a maximum beyond which solutions cease to exist. As a result, there is a limit to the extent to which an over-density can be balanced by intrinsic rather than extrinsic curvature on the initial slice. Even below this limit, iterative methods to construct initial data may converge to solutions on either one of the two branches, depending on the starting guess, leading to potentially inconsistent physical results in the evolution. - oai:arXiv.org:2509.26470v2 - gr-qc + No Dark Matter Axion During Minimal Higgs Inflation + https://arxiv.org/abs/2504.02952 + arXiv:2504.02952v2 Announce Type: replace-cross +Abstract: We study minimal versions of Higgs inflation in the presence of a massless QCD axion. While the inflationary energy scale of the metric variant is too high to accommodate isocurvature bounds, it was argued that Palatini Higgs inflation could evade these constraints. We show, however, that an energy-dependent decay constant enhances isocurvature perturbations, implying that axions can at most constitute a tiny fraction $< 10^{-5}$ of dark matter. This conclusion can be avoided in Einstein-Cartan gravity by an additional coupling of the axion to torsion, albeit for a very specific choice of parameters. Analogous constraints as well as the possibility to alleviate them are relevant for all inflationary models with a non-minimal coupling to gravity. + oai:arXiv.org:2504.02952v2 + hep-ph astro-ph.CO - Fri, 12 Dec 2025 00:00:00 -0500 + gr-qc + hep-th + Fri, 19 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Thomas W. Baumgarte, Katy Clough, John T. Giblin Jr - - - Progress on the ALETHEIA project and a new approach to mitigate events overlap - https://arxiv.org/abs/2511.08954 - arXiv:2511.08954v2 Announce Type: replace-cross -Abstract: The ALETHEIA project aims to search for low-mass dark matter using liquid helium (LHe)-filled time projection chambers (TPCs). While liquid argon and liquid xenon TPCs have been extensively employed in the field of direct dark matter detection, successful development of LHe TPCs has not yet been achieved. Launched in 2020, our project has made significant progress since then. These advancements have convinced us that a single-phase LHe TPC is technologically feasible. Compared to liquid xenon and liquid argon TPCs, one of the unique challenges for LHe TPCs is event overlap caused by the 13-second lifetime scintillation. We will demonstrate that this overlap can be entirely mitigated when the LHe temperature is maintained near 1.0 K. At this temperature, electron mobility is three orders of magnitude higher than at approximately 4.0 K, which is the temperature we initially proposed for the LHe TPC. - oai:arXiv.org:2511.08954v2 - physics.ins-det - astro-ph.IM - Fri, 12 Dec 2025 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Junhui Liao (on behalf of the ALETHEIA collaboration) + Claire Rigouzzo, Sebastian Zell - Questions related to the Deflection of Light by Gravity determined by Soldner, Einstein and Schwarzschild - https://arxiv.org/abs/2512.04128 - arXiv:2512.04128v2 Announce Type: replace-cross -Abstract: Before we discuss the deflection of light in a gravitational field, we give a brief overview of some basic physical formulas on photon properties, generation and propagation. The much debated problems of the redshift and the photon propagation in a gravitational field is then considered and applied to the calculation of the speed of light. Many citations are given in direct quotations to avoid any misunderstandings. If the quotations are in German, an English translation is provided. Based on this speed, calculated and measured results are recalled on the deflection of light, with emphasis on the deflection near the Sun. We conclude that the speed of light and the deflection angle can be determined by energy and momentum conservation principles. - oai:arXiv.org:2512.04128v2 - physics.hist-ph - astro-ph.SR + Lensing by black holes within astrophysical environments + https://arxiv.org/abs/2508.19333 + arXiv:2508.19333v2 Announce Type: replace-cross +Abstract: Astrophysical black holes are likely to be surrounded by various forms of matter in the form of disks or halos. While a number of studies have examined the impact of an environment on the lensing of light or gravitational waves from cosmological sources, these have, thus far, been carried out in either a Newtonian or post-Newtonian framework where the environment is superimposed on the black-hole spacetime. By using an exact solution in general relativity describing a black hole embedded within a realistic halo of Hernquist matter distribution, we study deflection angles and image amplification in a fully relativistic setup. It is shown that large ``bumps'', that also arise at the Newtonian and post-Newtonian levels, track the transition scale set by the halo parameters that control the strong-lensing upturn and can significantly adjust the inferences made for either the source or lens in various contexts. As an application, we consider ``echoes'' of gravitational waves, sourced by astrophysical lenses rather than being intrinsic to the compact object that produces the signal. + oai:arXiv.org:2508.19333v2 gr-qc - Fri, 12 Dec 2025 00:00:00 -0500 + astro-ph.GA + astro-ph.HE + hep-ph + Fri, 19 Dec 2025 00:00:00 -0500 replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Klaus Wilhelm, Bhola N. Dwivedi, Karsten Muller + http://creativecommons.org/licenses/by/4.0/ + 10.1103/tn1g-7tfj + Phys. Rev. D 112, 124062 (2025) + Gerasimos Kouniatalis, Arthur G. Suvorov, Kyriakos Destounis - Bayesian Model Selection with an Application to Cosmology - https://arxiv.org/abs/2512.09724 - arXiv:2512.09724v2 Announce Type: replace-cross -Abstract: We investigate cosmological parameter inference and model selection from a Bayesian perspective. Type Ia supernova data from the Dark Energy Survey (DES-SN5YR) are used to test the $\Lambda$CDM, $w$CDM, and CPL cosmological models. Posterior inference is performed via Hamiltonian Monte Carlo using the No-U-Turn Sampler (NUTS) implemented in NumPyro and analyzed with ArviZ in Python. Bayesian model comparison is conducted through Bayes factors computed using the bridgesampling library in R. The results indicate that all three models demonstrate similar predictive performance, but $w$CDM shows stronger evidence relative to $\Lambda$CDM and CPL. We conclude that, under the assumptions and data used in this study, $w$CDM provides a better description of cosmological expansion. - oai:arXiv.org:2512.09724v2 - stat.AP - astro-ph.CO - stat.ME - Fri, 12 Dec 2025 00:00:00 -0500 + Wave Front Sensing demodulated at the difference frequency between two phase-modulation sidebands in a compound interferometer configuration for a gravitational-wave detector + https://arxiv.org/abs/2511.17893 + arXiv:2511.17893v2 Announce Type: replace-cross +Abstract: Precise alignment sensing and control are essential for maintaining the stability of laser interferometric gravitational-wave detectors. Conventional Wave Front Sensing technique (WFS), which relies on the beat between the carrier and phase-modulated (PM) sidebands, is dominated by arm-axis signals when the carrier resonates in the full interferometer. This dominance limits the detection of other optical axes, such as the Power Recycling Cavity (PRC) and incident beam axes. To address this problem, we propose a novel sensing technique, "Phase-Modulated-sideband $\times$ Phase-Modulated-sideband Wave Front Sensing" (PMPMWFS), which demodulates the beat signal at the difference frequency between two anti-resonant PM sidebands. We derived the theoretical response of PMPMWFS and experimentally demonstrated it using the Power-Recycled X-arm (PRXARM) configuration of KAGRA. The results show that PMPMWFS effectively decouples angular fluctuation signals of the PRC and incident beam from those of the arm cavity and provides orthogonal signal components for the end mirror of the arm cavity. Furthermore, feedback control using PMPMWFS achieved stable interferometer locking for over one hour. These results demonstrate that PMPMWFS offers an effective sensing method for decoupling multiple alignment degrees of freedom in future gravitational-wave detectors. + oai:arXiv.org:2511.17893v2 + gr-qc + astro-ph.IM + Fri, 19 Dec 2025 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Nikoloz Gigiberia + Chiaki Hirose, Kenta Tanaka, Osamu Miyakawa, Takafumi Ushiba