Showing 1–50 of 1,548 results for author: Li, J

Connecting current and future dual AGN searches to LISA and PTA gravitational wave detections

Authors: 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

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 app… ▽ More 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. △ Less

Submitted 18 December, 2025; originally announced December 2025.

Comments: 20 pages, 16 figures; comments are welcome

An Improved Machine Learning Approach for RFI Mitigation in FAST-SETI Survey Archival Data

Authors: 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

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.… ▽ More 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. △ Less

Submitted 17 December, 2025; originally announced December 2025.

Comments: 14 pages, 2 tables, 8 figures, accepted for publication in The Astronomical Journal

Cold Gas Infall onto A Brightest Group Galaxy via A Gas-Rich Minor Merger

Authors: Ming-Yang Zhuang, Jinyi Shangguan, Yuan Bian, Yue Shen, Luis C. Ho, Min Du, Junyao Li, Zhao-Yu Li, Jing Wang

Abstract: Dust and cold gas are not uncommon in nearby early-type galaxies (ETGs), and represent an important aspect of their evolution. However, their origin has been debated for decades. Potential sources include internal processes (e.g., mass loss from evolved stars), external mechanisms (e.g., minor mergers or cooling flows), or a combination of both. Gas-rich minor mergers have long been proposed as an… ▽ More Dust and cold gas are not uncommon in nearby early-type galaxies (ETGs), and represent an important aspect of their evolution. However, their origin has been debated for decades. Potential sources include internal processes (e.g., mass loss from evolved stars), external mechanisms (e.g., minor mergers or cooling flows), or a combination of both. Gas-rich minor mergers have long been proposed as an important channel for cold gas fueling in both observations and simulations, but direct evidence of cold gas transportation via gas-rich minor mergers remains elusive, particularly in galaxy groups and clusters where environmental effects are prevalent. In this letter, we present the first unambiguous case of direct cold gas transportation onto a brightest group galaxy (BGG) at $z=0.25$, driven by an ongoing close-separation gas-rich minor merger with a mass ratio of $\sim1:56$. High-resolution JWST imaging reveals a heavily obscured, low-mass satellite that is barely visible at restframe optical wavelengths. Tidal stripping from this satellite deposits gas and dust onto the BGG, forming prominent $\sim$10 kpc dust lanes in situ. Cosmological simulations indicate that such interactions preferentially occur in gas-rich satellites undergoing their first infall in highly eccentric orbits. Our results highlight the pivotal role of gas-rich minor mergers in replenishing cold gas reservoirs and shaping the evolution of central ETGs in galaxy groups. △ Less

Submitted 15 December, 2025; originally announced December 2025.

Comments: 15 pages, 7 figures; submitted to ApJL

VLBI astrometry of radio stars to link radio and optical celestial reference frames III: 11 radio stars

Authors: Jingdong Zhang, Bo Zhang, Shuangjing Xu, Xiaofeng Mai, Mark J. Reid, Pengfei Jiang, Wen Chen, Fengchun Shu, Jinling Li, Lang Cui, Xingwu Zheng, Yan Sun, Zhaoxiang Qi

Abstract: The alignment between the radio-based International Celestial Reference Frame (ICRF) and the optical Gaia Celestial Reference Frame (Gaia-CRF) is critical for multi-waveband astronomy, yet systematic offsets at the optical bright end (G<13) limit their consistency. While radio stars offer a potential link between these frames, their utility has been restricted by the scarcity of precise Very Long… ▽ More The alignment between the radio-based International Celestial Reference Frame (ICRF) and the optical Gaia Celestial Reference Frame (Gaia-CRF) is critical for multi-waveband astronomy, yet systematic offsets at the optical bright end (G<13) limit their consistency. While radio stars offer a potential link between these frames, their utility has been restricted by the scarcity of precise Very Long Baseline Interferometry (VLBI) astrometry. In this study, we present new VLBI astrometry of 11 radio stars using the Very Long Baseline Array (VLBA), expanding the existing sample with positions, parallaxes, and proper motions measured. All 11 radio stars were detected, for 10 of which parallaxes and proper motions can be estimated, reaching a precision level of <1% in the best cases. These new samples greatly contribute to the link between ICRF and Gaia-CRF at the optical bright end. △ Less

Submitted 15 December, 2025; originally announced December 2025.

Comments: Submitted to MNRAS

The Merian Survey: A Statistical Census of Bright Satellites of Milky Way Analogs

Authors: Yue Pan, Shany Danieli, Jenny E. Greene, Jiaxuan Li, Alexie Leauthaud, Erin Kado-Fong, Yifei Luo, Abby Mintz, Alyson Brooks, Song Huang, Annika H. G. Peter, Joy Bhattacharyya, Lee S. Kelvin

Abstract: We present a statistical census of bright, star-forming satellite galaxies around Milky Way (MW) analogs using the first data release of the Merian Survey. Our sample consists of 393 MW analogs with stellar masses $10^{10.5} < M_{\star, \rm host} < 10^{10.9} M_\odot$ at redshifts $0.07 < z < 0.09$, all central galaxies of their own dark matter halos. Using photometric selection -- including magnit… ▽ More We present a statistical census of bright, star-forming satellite galaxies around Milky Way (MW) analogs using the first data release of the Merian Survey. Our sample consists of 393 MW analogs with stellar masses $10^{10.5} < M_{\star, \rm host} < 10^{10.9} M_\odot$ at redshifts $0.07 < z < 0.09$, all central galaxies of their own dark matter halos. Using photometric selection -- including magnitude, color, angular size, photometric redshift, and size-mass cuts -- we identify 793 satellite candidates around these 393 hosts. Our selection leverages two medium-band filters targeting H$α$ and [O \textsc{iii}] emission, enabling a nearly complete sample of star-forming, Magellanic Clouds-like satellites with $M_{\star, \rm sat} \gtrsim 10^{8} M_\odot$. We find that $\sim80\%$ of hosts have 0-3 massive satellites, and $13\pm4\%$ have two satellites (similar to the MW). Satellite abundance correlates with total stellar mass, and we provide significantly improved statistics for the most massive satellites at $\log_{10}[M_{\star, \rm sat}/M_{\odot}] \gtrsim 10$. The completeness-corrected radial distribution is less centrally concentrated than an NFW profile. In contrast, the Milky Way satellites are more centrally concentrated than the 50\% richest Merian systems, but are broadly consistent with the 50\% most centrally concentrated Merian systems. Our results highlight the power of medium-band photometry for satellite identification and provide a key benchmark for studying satellite quenching, environmental effects, and hierarchical galaxy formation. △ Less

Submitted 14 December, 2025; originally announced December 2025.

Comments: 22 pages, 8 figures. Published in ApJ in December, 2025

Counting voids and filaments: Betti Curves as a Powerful Probe for Cosmology

Authors: Jiayi Li, Cheng Zhao

Abstract: Topological analysis of galaxy distributions has gathered increasing attention in cosmology, as they are able to capture non-Gaussian features of large-scale structures (LSS) that are overlooked by conventional two-point clustering statistics. We utilize Betti curves, a summary statistic derived from persistent homology, to characterize the multiscale topological features of the LSS, including con… ▽ More Topological analysis of galaxy distributions has gathered increasing attention in cosmology, as they are able to capture non-Gaussian features of large-scale structures (LSS) that are overlooked by conventional two-point clustering statistics. We utilize Betti curves, a summary statistic derived from persistent homology, to characterize the multiscale topological features of the LSS, including connected components, loops, and voids, as a complementary cosmological probe. Using halo catalogs from the \textsc{Quijote} suite, we construct Betti curves, assess their sensitivity to cosmological parameters, and train automated machine learning based emulators to model their dependence on cosmological parameters. Our Bayesian inference recovers unbiased estimation of cosmological parameters, notably $n_{\mathrm{s}}$, $σ_8$, and $Ω_{\mathrm{m}}$, while validation on sub-box simulations confirms robustness against cosmic variance. We further investigate the impact of redshift-space distortions (RSD) on Betti curves and demonstrate that including RSD enhances sensitivity to growth-related parameters. By jointly analyzing Betti curves and the power spectrum, we achieve significantly tightened constraints than using power spectrum alone on parameters such as $n_{\mathrm{s}}$, $σ_8$, and $w$. These findings highlight Betti curves -- especially when combined with traditional two-point statistics -- as a promising, interpretable tool for future galaxy survey analyses. △ Less

Submitted 8 December, 2025; originally announced December 2025.

Comments: 22 pages, 15 figures

Rebrightenings of gamma-ray burst afterglows from an increasing magnetic inclination angle of a nascent magnetar

Authors: M. Xu, J. Li, C. F. Xiao, H. H. Qiu

Abstract: A nascent magnetar, accompanying a gamma-ray burst (GRB) explosion, releases enormous rotational energy via magnetic dipole radiation. The energy loss rate of the magnetar is determined by the strength of the magnetic field at the pole. We investigated the effect of the magnetic inclination angle on the energy loss rate. The released energy is injected into the GRB jet and shapes the light curves… ▽ More A nascent magnetar, accompanying a gamma-ray burst (GRB) explosion, releases enormous rotational energy via magnetic dipole radiation. The energy loss rate of the magnetar is determined by the strength of the magnetic field at the pole. We investigated the effect of the magnetic inclination angle on the energy loss rate. The released energy is injected into the GRB jet and shapes the light curves of GRB afterglow. Different evolutionary approaches lead to different curves shapes.A shallow decay phase in GRB X-ray afterglow may result from energy injection from a magnetar with a fixed inclination angle. A two-plateau phase may result from a decreasing inclination angle scenario. In this study, we considered an increasing inclination angle scenario. The energy loss rate of the magnetar increases as the magnetic inclination angle grows. Our analysis reveals that as the lost rotational energy injected into the GRB jet increases, rebrightening phases occur in the GRB afterglows. The rebrightening features are slight and short-lived. The observed afterglow rebrightening of GRB 170822A and GRB 230414B can be well explained within our framework. Some GRB X-ray afterglows that exhibit slight and early rebrightenings may result from an increasing magnetic inclination angle of a nascent magnetar. △ Less

Submitted 6 December, 2025; originally announced December 2025.

Comments: 7 pages, 3 figures, 1 table, A&A, in press

287,872 Supermassive Black Holes Masses: Deep Learning Approaching Reverberation Mapping Accuracy

Authors: Yuhao Lu, HengJian SiTu, Jie Li, Yixuan Li, Yang Liu, Wenbin Lin, Yu Wang

Abstract: We present a population-scale catalogue of 287,872 supermassive black hole masses with high accuracy. Using a deep encoder-decoder network trained on optical spectra with reverberation-mapping (RM) based labels of 849 quasars and applied to all SDSS quasars up to $z=4$, our method achieves a root-mean-square error of $0.058$\,dex, a relative uncertainty of $\approx 14\%$, and coefficient of determ… ▽ More We present a population-scale catalogue of 287,872 supermassive black hole masses with high accuracy. Using a deep encoder-decoder network trained on optical spectra with reverberation-mapping (RM) based labels of 849 quasars and applied to all SDSS quasars up to $z=4$, our method achieves a root-mean-square error of $0.058$\,dex, a relative uncertainty of $\approx 14\%$, and coefficient of determination $R^{2}\approx0.91$ with respect to RM-based masses, far surpassing traditional single-line virial estimators. Notably, the high accuracy is maintained for both low ($<10^{7.5}\,M_\odot$) and high ($>10^{9}\,M_\odot$) mass quasars, where empirical relations are unreliable. △ Less

Submitted 4 December, 2025; originally announced December 2025.

Comments: 14 pages, 9 figures. Submitted to Journal of High Energy Astrophysics

The DREAMS Project: Disentangling the Impact of Halo-to-Halo Variance and Baryonic Feedback on Milky Way Dark Matter Speed Distributions

Authors: Ethan Lilie, Jonah C. Rose, Mariangela Lisanti, Alex M. Garcia, Paul Torrey, Kassidy E. Kollmann, Jiaxuan Li, Olivia Mostow, Bonny Y. Wang, Stephanie O'Neil, Xuejian Shen, Alyson M. Brooks, Arya Farahi, Nitya Kallivayalil, Lina Necib, Andrew B. Pace, Mark Vogelsberger

Abstract: Direct detection experiments require information about the local dark matter speed distribution to produce constraints on dark matter candidates, or infer their properties in the event of a discovery. In this paper, we analyze how the uncertainty in the dark matter speed distribution near the Sun is affected by baryonic feedback, halo-to-halo variance, and halo mass. To do so, we harness the stati… ▽ More Direct detection experiments require information about the local dark matter speed distribution to produce constraints on dark matter candidates, or infer their properties in the event of a discovery. In this paper, we analyze how the uncertainty in the dark matter speed distribution near the Sun is affected by baryonic feedback, halo-to-halo variance, and halo mass. To do so, we harness the statistical power of the new DREAMS Cold Dark Matter simulation suite, which is comprised of 1024 zoom-in Milky Way-mass halos with varied initial conditions as well as cosmological and astrophysical parameters. Applying a normalizing flows emulator to these simulations, we find that the uncertainty in the local DM speed distribution is dominated by halo-to-halo variance and, to a lesser extent, uncertainty in host halo mass. Uncertainties in supernova and black hole feedback (from the IllustrisTNG model in this case) are negligible in comparison. Using the DREAMS suite, we present a state-of-the-art prediction for the DM speed distribution in the Milky Way. Although the Standard Halo Model is contained within the uncertainty of this prediction, individual galaxies may have distributions that differ from it. Lastly, we apply our DREAMS results to the XENON1T experiment and demonstrate that the astrophysical uncertainties are comparable to the experimental ones, solidifying previous results in the literature obtained with a smaller sample of simulated Milky Way-mass halos. △ Less

Submitted 3 December, 2025; originally announced December 2025.

Comments: 26 pages, 7 figures, 3 appendices, 7 additional figures. See also arxiv.2512.00148 and arXiv:2512.02095

A Deep Chandra X-ray Survey of a Luminous Quasar Sample at $z\sim$ 7

Authors: Xiangyu Jin, Feige Wang, Jinyi Yang, Xiaohui Fan, Fuyan Bian, Jiang-Tao Li, Weizhe Liu, Yichen Liu, Jianwei Lyu, Maria Pudoka, Wei Leong Tee, Yunjing Wu, Haowen Zhang, Yongda Zhu

Abstract: We present new Chandra observations of seven luminous quasars at $z>6.5$. Combined with archival Chandra observations of all other known quasars, they form nearly complete X-ray observations of all currently known $z\sim7$ quasars with $M_{1450}<-26.5$, except for J0313$-$1806 at $z=7.642$ and J0910$-$0414 at $z=6.636$. Together with existing ground-based NIR spectroscopy and ALMA observations, we… ▽ More We present new Chandra observations of seven luminous quasars at $z>6.5$. Combined with archival Chandra observations of all other known quasars, they form nearly complete X-ray observations of all currently known $z\sim7$ quasars with $M_{1450}<-26.5$, except for J0313$-$1806 at $z=7.642$ and J0910$-$0414 at $z=6.636$. Together with existing ground-based NIR spectroscopy and ALMA observations, we investigate the correlations between X-ray emission (the X-ray luminosity $L_{\rm X}$ and the optical/UV-to-X-ray spectral slope $α_{\rm OX}$) and various quasar properties (rest-UV luminosity $L_{\mathrm{2500\ \mathring{A}}}$, bolometric luminosity $L_{\rm bol}$, C IV blueshift, and infrared luminosity $L_{\rm IR}$). We find most $z>6.5$ quasars follow a similar $α_{\rm OX}-L_{\mathrm{2500\ \mathring{A}}}$ relation as $z\sim1-6$ quasars, but also display a large scatter. We find a potential correlation between $α_{\rm OX}$ and the C IV blueshift, suggesting a soft optical/UV-to-X-ray SED shape is frequently associated with fast disk winds. Furthermore, we analyze the X-ray spectrum of 11 quasars at $z>6.5$ with Chandra detection, and find the best-fit photon index $Γ$ is $2.41\pm0.27$, which is likely driven by high accretion rates of $z>6.5$ quasars. In addition, we find there are no significant correlations between either $L_{\rm X}$ and $L_{\rm IR}$, nor $L_{\rm bol}$ and $L_{\rm IR}$, suggesting no strong correlations between quasar luminosity and star formation luminosity for the most luminous quasars at $z>6.5$. △ Less

Submitted 2 December, 2025; originally announced December 2025.

Comments: 17 pages, 8 figures, 3 tables, accepted for publication in ApJ

The DREAMS Project: Disentangling the Impact of Halo-to-Halo Variance and Baryonic Feedback on Milky Way Dark Matter Density Profiles

Authors: Alex M. Garcia, Jonah C. Rose, Paul Torrey, Andrea Caputo, Mariangela Lisanti, Andrew B. Pace, Hongwan Liu, Abdelaziz Hussein, Haozhe Liu, Francisco Villaescusa-Navarro, John Barry, Ilem Leisher, Belén Costanza, Jonathan Kho, Ethan Lilie, Jiaxuan Li, Niusha Ahvazi, Aklant Bhowmick, Tri Nguyen, Stephanie O'Neil, Xiaowei Ou, Xuejian Shen, Arya Farahi, Nitya Kallivayalil, Lina Necib , et al. (1 additional authors not shown)

Abstract: Astrophysical searches for dark matter in the Milky Way require a reliable model for its density distribution, which in turn depends on the influence of baryonic feedback on the Galaxy. In this work, we utilize a new suite of Milky Way-mass halos from the DREAMS Project, simulated with Cold Dark Matter (CDM),to quantify the influence of baryon feedback and intrinsic halo-to-halo variance on dark m… ▽ More Astrophysical searches for dark matter in the Milky Way require a reliable model for its density distribution, which in turn depends on the influence of baryonic feedback on the Galaxy. In this work, we utilize a new suite of Milky Way-mass halos from the DREAMS Project, simulated with Cold Dark Matter (CDM),to quantify the influence of baryon feedback and intrinsic halo-to-halo variance on dark matter density profiles. Our suite of 1024 halos varies over supernova and black hole feedback parameters from the IllustrisTNG model, as well as variations in two cosmological parameters. We find that Milky Way-mass dark matter density profiles in the IllustrisTNG model are largely insensitive to astrophysics and cosmology variations, with the dominant source of scatter instead arising from halo-to-halo variance. However, most of the (comparatively minor) feedback-driven variations come from the changes to supernova prescriptions. By comparing to dark matter-only simulations, we find that the strongest supernova wind energies are so effective at preventing galaxy formation that the halos are nearly entirely collisionless dark matter. Finally, regardless of physics variation, all the DREAMS halos are roughly consistent with a halo contracting adiabatically from the presence of baryons, unlike models that have bursty stellar feedback. This work represents a step toward assessing the robustness of Milky Way dark matter profiles, with direct implications for dark matter searches where systematic uncertainty in the density profile remains a major challenge. △ Less

Submitted 2 December, 2025; originally announced December 2025.

Comments: 19 pages, 9 figures, 1 table, 4 appendices. Comments Welcome! See also arxiv.2512.00148

The DREAMS Project: Disentangling the Impact of Halo-to-Halo Variance and Baryonic Feedback on Milky Way Satellite Galaxies

Authors: Jonah C. Rose, Mariangela Lisanti, Paul Torrey, Francisco Villaescusa-Navarro, Alex M. Garcia, Arya Farahi, Carrie Filion, Alyson M. Brooks, Nitya Kallivayalil, Kassidy E. Kollmann, Ethan Lilie, Jiaxuan Li, Olivia Mostow, Akaxia Cruz, Tri Nguyen, Sandip Roy, Andrew B. Pace, Niusha Ahvazi, Stephanie O'Neil, Xuejian Shen, Francis-Yan Cyr-Racine, Adrian M. Price-Whelan, Marla Geha, Lina Necib, Mark Vogelsberger , et al. (2 additional authors not shown)

Abstract: We analyze the properties of satellite galaxies around 1,024 Milky Way-mass hosts from the DREAMS Project, simulated within a $Λ$CDM cosmology. Utilizing the TNG galaxy-formation model, the DREAMS simulations incorporate both baryonic physics and cosmological uncertainties for a large sample of galaxies with diverse environments and formation histories. We investigate the relative impact of the ph… ▽ More We analyze the properties of satellite galaxies around 1,024 Milky Way-mass hosts from the DREAMS Project, simulated within a $Λ$CDM cosmology. Utilizing the TNG galaxy-formation model, the DREAMS simulations incorporate both baryonic physics and cosmological uncertainties for a large sample of galaxies with diverse environments and formation histories. We investigate the relative impact of the physical uncertainty from the galaxy-formation model on predicted satellite properties using four metrics: the satellite stellar mass function, radial distribution, inner slope of dark matter density profile, and stellar half-light radius. We compare these predictions to observations from the SAGA Survey and the DREAMS N-body simulations and find that uncertainties from baryonic physics modeling are subdominant to the scatter arising from halo-to-halo variance. Where baryonic modeling does affect satellites, the supernova wind energy has the largest effect on the satellite properties that we investigate. Specifically, increased supernova wind energy suppresses the stellar mass of satellites and results in more extended stellar half-light radii. The adopted wind speed has only a minor impact, and other astrophysical and cosmological parameters show no measurable effect. Our findings highlight the robustness of satellite properties against uncertainties in baryonic physics modeling. △ Less

Submitted 1 December, 2025; originally announced December 2025.

Comments: 16 pages, 5 figures, 2 tables, and 2 appendices with an additional 4 figures

Bayesian inferences on covariant density functionals from multimessenger astrophysical data: The influences of parametrizations of density dependent couplings

Authors: Guo-Jun Wei, Jia-Jie Li, Armen Sedrakian, Yong-Jia Wang, Qing-Feng Li, Fu-Hu Liu

Abstract: Covariant density functionals have been successfully applied to the description of finite nuclei and dense nuclear matter. These functionals are often constructed by introducing density dependence into the nucleon-meson couplings, typically through functions that depend only on the vector, i.e., proper baryon density. In this work, we employ a Bayesian framework to investigate how different parame… ▽ More Covariant density functionals have been successfully applied to the description of finite nuclei and dense nuclear matter. These functionals are often constructed by introducing density dependence into the nucleon-meson couplings, typically through functions that depend only on the vector, i.e., proper baryon density. In this work, we employ a Bayesian framework to investigate how different parametrizations, characterized by distinct functional forms and by their dependencies on vector and scalar densities, affect the properties of dense matter and compact stars. Our analysis demonstrates that although all considered parametrizations yield broadly comparable inferences, the differences in the equation of state and the symmetry energy remain significant at suprasaturation densities, reflecting the sensitivity to the chosen functional form of the density dependence. We find that allowing the nuclear saturation properties in the isoscalar channel, including the skewness coefficient $Q_{sat}$, to be freely adjusted provides adequate flexibility for the current modeling of nuclear and neutron star matter. In contrast, the isovector channel requires further refinement, with freedom extended at least up to the curvature coefficient $K_{sym}$ to capture variations in the symmetry energy and particle composition at high densities. This work advances prior studies by implementing a rational-function parametrization of the density dependence, informed and constrained by multimessenger astrophysical observations. △ Less

Submitted 1 December, 2025; originally announced December 2025.

Comments: 13 pages, 5 figures

Simulating AGN feedback in galaxy clusters with pre-existing turbulence

Authors: Jia-Lun Li, H. -Y. Karen Yang

Abstract: Feedback from active galactic nuclei (AGN) is believed to play a significant role in suppressing cooling flows in cool-core (CC) clusters. Turbulence in the intracluster medium (ICM), which may be induced by AGN activity or pre-existing motions, has been proposed as a potential heating mechanism based on analysis of Chandra X-ray surface brightness fluctuations. However, subsequent simulation resu… ▽ More Feedback from active galactic nuclei (AGN) is believed to play a significant role in suppressing cooling flows in cool-core (CC) clusters. Turbulence in the intracluster medium (ICM), which may be induced by AGN activity or pre-existing motions, has been proposed as a potential heating mechanism based on analysis of Chandra X-ray surface brightness fluctuations. However, subsequent simulation results have found the subdominant role of turbulence in heating the ICM. To investigate this discrepancy, we perform three-dimensional hydrodynamic simulations of a Perseus-like cluster including both AGN feedback and pre-existing turbulence, which is stirred to the observationally constrained level in the Perseus cluster. Our results indicate that, although the velocity field is dominated by the pre-existing turbulence, AGN heating through bubbles and shocks remains significant. More importantly, analysis of the velocity structure function and the energy power spectrum shows that the turbulent heating rate is smaller than the radiative cooling rate, especially in the cluster core. Our results offer insights relevant for recent XRISM observations and indicate that turbulent heating alone cannot offset radiative cooling in CC clusters. △ Less

Submitted 28 November, 2025; originally announced November 2025.

Comments: 16 pages, 11 figures, submitted to ApJ

The diverse morphology of gravitational wave signals from merging neutron-star white-dwarf binaries

Authors: Shenghua Yu, Youjun Lu, C. Simon Jeffery, Zhanwen Han, DongDong Liu, Jie Yang, Xilong Fan, Bo Peng, Jianbin Li

Abstract: In sufficiently compact neutron star-white dwarf (NSWD) binary systems, orbital decay means the white dwarf eventually fills its shrinking Roche lobe, initiating a phase of mass transfer. The exchange of angular momentum-both internal and external-plays a critical role in determining the binary's evolutionary outcome. For neutron stars with relatively low magnetic fields and spin frequencies, whet… ▽ More In sufficiently compact neutron star-white dwarf (NSWD) binary systems, orbital decay means the white dwarf eventually fills its shrinking Roche lobe, initiating a phase of mass transfer. The exchange of angular momentum-both internal and external-plays a critical role in determining the binary's evolutionary outcome. For neutron stars with relatively low magnetic fields and spin frequencies, whether the orbital separation continues to shrink depends on the interplay between gravitational wave (GW) radiation and mass transfer dynamics. We compute the orbital evolution of NSWD binaries across a broad parameter space, incorporating four key variables. Our results reveal distinct boundaries in the NS-WD mass-mass diagram: binaries with white dwarf masses above these thresholds undergo rapid orbital decay and direct coalescence. The dependence of these boundaries on system parameters indicates that Roche-lobe-filling NSWD binaries can follow multiple evolutionary pathways -- a phenomenon we refer to as branched or polymorphic evolution. NSWD binary systems emit strong and diverse GW signals, many of which would be detectable by space-based GW observatories. The morphology of the evolving GW waveform provides a direct diagnostic for the NSWD binary configuration, including any contribution from an accretion disk. Our models can provide critical waveform templates for identifying merging binary signals in real-time GW data. △ Less

Submitted 25 November, 2025; originally announced November 2025.

Comments: 13 pages, 7 figures, accepted for publication in MNRAS

Stellar Parameters of BOSS M dwarfs in SDSS-V DR19

Authors: Dan Qiu, Jennifer A. Johnson, Chao Liu, Diogo Souto, Ilija Medan, Guy S. Stringfellow, Zachary Way, Yuan-sen Ting, Andrew R. Casey, Bárbara Rojas-Ayala, Ricardo López-Valdivia, Ying-Yi Song, Bo Zhang, Jiadong Li, Aida Behmard, Szabolcs Mészáros, Keivan G. Stassun, José G. Fernández-Trincado

Abstract: We utilized the Stellar LAbel Machine (SLAM), a data-driven model based on Support Vector Regression, to derive stellar parameters ([Fe/H], $T_{\rm eff}$, and $\log{g}$) for SDSS-V M dwarfs using low-resolution optical spectra (R$\sim$2000) obtained with the BOSS spectrographs. These parameters are calibrated using LAMOST F, G or K dwarf companions ([Fe/H]), and APOGEE Net ($T_{\rm eff}$ and… ▽ More We utilized the Stellar LAbel Machine (SLAM), a data-driven model based on Support Vector Regression, to derive stellar parameters ([Fe/H], $T_{\rm eff}$, and $\log{g}$) for SDSS-V M dwarfs using low-resolution optical spectra (R$\sim$2000) obtained with the BOSS spectrographs. These parameters are calibrated using LAMOST F, G or K dwarf companions ([Fe/H]), and APOGEE Net ($T_{\rm eff}$ and $\log{g}$), respectively. Comparisons of SLAM predicted [Fe/H] values between two components of M+M dwarfs wide binaries show no bias but with a scatter of 0.11 dex. Further comparisons with two other works, which also calibrated the [Fe/H] of M dwarfs by using the F/G/K companions, reveal biases of -0.06$\pm$0.16 dex and 0.02$\pm$0.14 dex, respectively. The SLAM-derived effective temperatures agree well with the temperature which is calibrated by using interferometric angular diameters (bias: -27$\pm$92 K) and those of the LAMOST (bias: -34$\pm$65 K), but are systematically lower than those from an empirical relationship between the color index and $T_{\rm eff}$ by 146$\pm$45 K. The SLAM surface gravity aligns well with those of LAMOST (bias: -0.01$\pm$0.07 dex) and those derived from the stellar mass and radius (bias: -0.04$\pm$0.09 dex). Finally, we investigated a bias in [Fe/H] between SLAM and APOGEE ASPCAP. It depends on ASPCAP's [Fe/H] and $T_{\rm eff}$, we provide an equation to correct the ASPCAP metallicities. △ Less

Submitted 25 November, 2025; originally announced November 2025.

Comments: 19 pages, 12 Figures

On the baryon budget in the X-ray-emitting circumgalactic medium of Milky Way-mass galaxies

Authors: Yi Zhang, Soumya Shreeram, Gabriele Ponti, Johan Comparat, Andrea Merloni, Zhijie Qu, Jiangtao Li, N. Joel Bregman, Taotao Fang

Abstract: Recent observations with SRG/eROSITA have revealed the average X-ray surface brightness profile of the X-ray-emitting circumgalactic medium (CGM) around Milky Way (MW)-mass galaxies, offering valuable insights into the baryon mass in these systems. However, the estimation of the baryon mass depends critically on several assumptions regarding the gas density profile, temperature, metallicity, and t… ▽ More Recent observations with SRG/eROSITA have revealed the average X-ray surface brightness profile of the X-ray-emitting circumgalactic medium (CGM) around Milky Way (MW)-mass galaxies, offering valuable insights into the baryon mass in these systems. However, the estimation of the baryon mass depends critically on several assumptions regarding the gas density profile, temperature, metallicity, and the underlying halo mass distribution. Here, we assess how these assumptions affect the inferred baryon mass of the X-ray-emitting CGM in MW-mass galaxies, based on the stacked eROSITA signal. We find that variations in temperature profiles and uncertainties in the halo mass introduce the dominant sources of uncertainty, resulting in X-ray-emitting baryon mass estimates that vary by nearly a factor of four ($0.8-3.5\times10^{11} M_\odot$). Assumptions about metallicity contribute an additional uncertainty of approximately $50\%$. We emphasize that accurate X-ray spectral constraints on gas temperature and metallicity, along with careful modeling of halo mass uncertainty, are essential for accurately estimating the baryon mass for MW-mass galaxies. Future X-ray microcalorimeter missions will be crucial for determining the hot CGM properties and closing the baryon census at the MW-mass scale. △ Less

Submitted 21 November, 2025; originally announced November 2025.

Comments: 12 pages, 3 figures, 3 tables. Accepted by A&A

TransFit-CSM: A Fast, Physically Consistent Framework for Interaction-Powered Transients

Authors: Yu-Hao Zhang, Liang-Duan Liu, Ze-Xin Du, Guang-Lei Wu, Jing-Yao Li, Yun-Wei Yu

Abstract: We present TransFit-CSM, a fast and physically consistent framework for modeling interaction-powered transients. The method self-consistently couples the ejecta circumstellar medium (CSM) shock dynamics to radiative diffusion from a moving heating boundary tied to the shocks, so that both the photon escape path and the effective diffusion time evolve with radius and time. We solve the mass and mom… ▽ More We present TransFit-CSM, a fast and physically consistent framework for modeling interaction-powered transients. The method self-consistently couples the ejecta circumstellar medium (CSM) shock dynamics to radiative diffusion from a moving heating boundary tied to the shocks, so that both the photon escape path and the effective diffusion time evolve with radius and time. We solve the mass and momentum equations for the forward and reverse shocks together with the diffusion equation in the unshocked CSM. TransFit-CSM reproduces the canonical sequence of an early dark phase, a diffusion-mediated rise and peak, and a post-interaction cooling tail, and it clarifies why Arnett-like peak scalings break down in optically thick CSM. The framework is well suited for Bayesian inference and constrains physical parameters of the ejecta and CSM from bolometric or joint multi-band light curves. Applications to SN 2006gy and SN 2010jl yield accurate fits and physically interpretable posteriors, highlighting the dominant role of pre-supernova mass loss in shaping the observables. Because it is both computationally efficient and physically grounded, TransFit-CSM bridges simple analytic prescriptions and radiation-hydrodynamic simulations, enabling population-level inference for current and future time-domain surveys. △ Less

Submitted 17 November, 2025; originally announced November 2025.

Comments: 19 pages 10 figures

Wide-Field X-ray Polarimetry for High Energy Astronomical Transients: First results of the pathfinder CXPD Cubesat Mission

Authors: Hong-Bang Liu, Zu-Ke Feng, Huan-Bo Feng, Di-Fan Yi, Li-Rong Xie, Yan-Jun Xie, Zong-Wang Fan, Jin Zhang, Wen-Jin Xie, Xue-Feng Huang, Wei Deng, Fei Xie, Dong Wang, Zi-Li Li, Hui Wang, Ran Chen, Shi-Qiang Zhou, Kai Chen, Jin Li, Qian Liu, Shi Chen, Rui-Ting Ma, Bin-Long Wang, Zhen-Yu Tang, Hang-Zhou Li , et al. (5 additional authors not shown)

Abstract: The Low Energy Polarization Detector (LPD) is a key component of the next-generation large-scale Gamma-Ray Burst polarimeter, POLAR-2. It is designed for polarization observations of transient sources in the soft X-ray energy range with a wide field of view (FOV). To validate the key technologies required for wide-FOV X-ray polarization measurements, the Cosmic X-ray Polarization Detector (CXPD) C… ▽ More The Low Energy Polarization Detector (LPD) is a key component of the next-generation large-scale Gamma-Ray Burst polarimeter, POLAR-2. It is designed for polarization observations of transient sources in the soft X-ray energy range with a wide field of view (FOV). To validate the key technologies required for wide-FOV X-ray polarization measurements, the Cosmic X-ray Polarization Detector (CXPD) CubeSat was developed as a prototype for the LPD. The CXPD is equipped with two Gas Microchannel Plate Pixel Detectors (GMPDs) that measure X-ray polarization via the photoelectric effect, where ejected photoelectrons produce ionization tracks in the gas which are imaged to reconstruct their emission directions. Laboratory calibrations of the modulation factor and energy spectra were successfully performed using linear polarized X-ray sources at 2.98 keV, 4.51 keV, 6.40 keV, and 8.05 keV. Since its launch in June 2023, the CXPD has successfully completed critical in-orbit technology verification. It has also performed polarization observations of two bright X-ray sources Sco X-1 and the transient Swift J1727.8-1613 yielding constraints on their polarization degrees and angles. Notably, this was the first time that an anti-coincidence detector had been implemented in an X-ray polarimeter, enabling in-orbit verification of the charged-particle background rejection algorithm. These results demonstrate the feasibility of wide-field soft X-ray polarization measurements and provide essential guidance for the development of the LPD for the POLAR-2 mission, thereby advancing the frontier of X-ray polarization astronomy. △ Less

Submitted 17 November, 2025; originally announced November 2025.

Constraints on the canonical single-field slow-roll inflation model from observations

Authors: Jun Li, Guang-Hai Guo

Abstract: In this paper we use two methods to constrain the the canonical single-field slow-roll inflation model. The first method exploits the analytic slow-roll-parameter dependence of primordial perturbations, and the second consists of a phenomenological parameterization of the primordial spectra of both scalar and tensor perturbations. We constrain the slow-roll parameters directly by adopting the late… ▽ More In this paper we use two methods to constrain the the canonical single-field slow-roll inflation model. The first method exploits the analytic slow-roll-parameter dependence of primordial perturbations, and the second consists of a phenomenological parameterization of the primordial spectra of both scalar and tensor perturbations. We constrain the slow-roll parameters directly by adopting the latest datasets, including Planck satellite data, BICEP2/Keck data and Baryon Acoustic Oscillation data. An advantage of this method is that we can work out the predictions of single-field slow-roll inflation model by using these constrained slow-roll parameters. We illustrate the predictions of the parameters characterizing the scalar power spectrum and constrain some inflation models. We find that the inflation model with monomial potential is disfavored, and the inflation models with a concave potential, such as the Starobinsky inflation model, brane inflation model are preferred. From the constraints on the slow-roll parameters, the derived tensor spectral index in the single-field slow-roll inflation model is quite small, namely $|n_t|\lesssim 4.7\times 10^{-3}$ which will be very difficult to be measured by CMB data only in the future, and the absolute value of derived running of tensor spectral index is not larger than $1.56\times 10^{-4}$ at $95\%$ confidence level. △ Less

Submitted 14 November, 2025; originally announced November 2025.

Global Distribution of the Key Species on the Surface of Europa

Authors: Jiazheng Li, Yinsi Shou, Cheng Li, Xianzhe Jia

Abstract: The icy surface of Europa is continuously bombarded by ions and electrons from Jupiter's magnetosphere. The bombardment of the particles dissociates water molecules on the surface of Europa and introduces impurities to the icy surface. Such processes lead to the generation of the nonwater species on the surface of Europa. These chemical species are closely related to the chemistry of the icy crust… ▽ More The icy surface of Europa is continuously bombarded by ions and electrons from Jupiter's magnetosphere. The bombardment of the particles dissociates water molecules on the surface of Europa and introduces impurities to the icy surface. Such processes lead to the generation of the nonwater species on the surface of Europa. These chemical species are closely related to the chemistry of the icy crust and the subsurface ocean, as well as Europa's habitability. However, our knowledge of the global distribution of these species is limited due to the sparse satellite and telescope observations on Europa. In this study, we combine a Europa plasma model and a chemical-transport model to simulate the global distribution of the key nonwater species on the surface of Europa. The initial results from our model agree well with the existing observations on the distributions of H2SO4 and SO2 but they show a significant discrepancy with the observed distribution of H2O2. Sensitivity tests on the reaction rate coefficients indicate that the simulated global distribution of all three species fit the observations well if the reaction rate coefficients in the ice are reduced by one order of magnitude. This finding provides a useful constraint on the rate coefficient of the chemical reactions in the ice. Furthermore, our model predicts that the O2 on the surface ice of Europa is concentrated on the leading hemisphere. The simulated global distribution of the key species on Europa may provide useful guidance for future missions to Europa, such as Europa Clipper and JUICE. △ Less

Submitted 13 November, 2025; v1 submitted 12 November, 2025; originally announced November 2025.

Journal ref: ApJ 993 122 (2025)

Revisiting the Hubble tension problem in the framework of holographic dark energy

Authors: Jun-Xian Li, Shuang Wang

Abstract: The Hubble tension problem is one of the most significant challenges in modern cosmology. In this paper, we study the Hubble tension problem in the framework of holographic dark energy (HDE). To perform a systematic and comprehensive analysis, we select six representative theoretical models from all four categories of HDE. For the observational data, we adopt the Baryon Acoustic Oscillation (BAO)… ▽ More The Hubble tension problem is one of the most significant challenges in modern cosmology. In this paper, we study the Hubble tension problem in the framework of holographic dark energy (HDE). To perform a systematic and comprehensive analysis, we select six representative theoretical models from all four categories of HDE. For the observational data, we adopt the Baryon Acoustic Oscillation (BAO) data from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2), a collection of alternative BAO data, the Cosmic Microwave Background (CMB) distance priors from the $Planck$ 2018, the type Ia supernovae (SN) data from the PantheonPlus, Union3, and DESY5 compilations. We find that HDE models that employ the Hubble scale or its combinations as the IR cutoff cannot alleviate the Hubble tension problem. In contrast, HDE models that employ the future event horizon as the IR cutoff can significantly alleviate the Hubble tension problem. It must be stressed that these two key conclusions hold true for cases of adopting different theoretical HDE models and different observational data. Our findings advocate for further exploration of HDE models using other types of cosmological observations. △ Less

Submitted 12 November, 2025; originally announced November 2025.

Comments: 16 pages, 10 figures, 8 tables. comments are welcome!

Detection of Lensed Gravitational Waves from dark matter halos with deep learning

Authors: Mengfei Sun, Jie Wu, Jin Li, Nan Yang, Xianghe Ma, Borui Wang, Minghui Zhang, Yuanhong Zhong

Abstract: Lensed gravitational waves (GWs) provide a new window into the study of dark matter substructures, yet the faint interference signatures they produce are buried in detector noise. To address this challenge, we develop a deep learning framework based on a residual one-dimensional convolutional neural network for lensed GW identification under multiband observations. The model directly processes mul… ▽ More Lensed gravitational waves (GWs) provide a new window into the study of dark matter substructures, yet the faint interference signatures they produce are buried in detector noise. To address this challenge, we develop a deep learning framework based on a residual one-dimensional convolutional neural network for lensed GW identification under multiband observations. The model directly processes multiband waveforms from binary neutron star systems, covering the early inspiral observed by the DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) and the late inspiral observed by the Einstein Telescope (ET), corresponding approximately to the wave-optics and geometrical-optics regimes, respectively. It enables end-to-end classification of five classes: pure noise, unlensed GWs, and three representative lensed GWs corresponding to singular isothermal sphere (SIS), cored isothermal sphere (CIS), and Navarro-Frenk-White (NFW) profiles. A dataset of 10^6 simulated samples was constructed with signal-to-noise ratios (SNR) ranging from 5 to 100. The deep learning model with multiband observations achieves an accuracy of 97.0% and a macro-averaged F1 score of 0.97, significantly exceeding the single-detector performance, where DECIGO and ET reach 72.8% and 62.3%, respectively. Even in the low-SNR regime (SNR < 20), the model maintains an accuracy above 63%, while in the high-SNR regime (SNR > 80), its accuracy approaches 99.8%. These results demonstrate that multiband GW observations effectively enhance the detection of lensed GWs within complex noise environments, providing a robust and efficient pathway for the automated identification of lensed GWs in future multiband observations. △ Less

Submitted 23 November, 2025; v1 submitted 12 November, 2025; originally announced November 2025.

Mock Observations for the CSST Mission: HSTDM--Synthetic Data Generation

Authors: SiYuan Tan, WenYin Duan, YiLong Zhang, YiPing Ao, Yan Gong, ZhenHui Lin, Xuan Zhang, Yong Shi, Jing Tang, Jing Li, RuiQing Mao, Sheng-Cai Shi

Abstract: The High Sensitivity Terahertz Detection Module (HSTDM), a key component of the backend modules on board the China Space Station Telescope (CSST), will offer great opportunities for the discovery of Terahertz Astronomy, with implications that extend well beyond China to the global astronomical community. It is imperative that the raw data collected by HSTDM undergoes meticulous calibration and pro… ▽ More The High Sensitivity Terahertz Detection Module (HSTDM), a key component of the backend modules on board the China Space Station Telescope (CSST), will offer great opportunities for the discovery of Terahertz Astronomy, with implications that extend well beyond China to the global astronomical community. It is imperative that the raw data collected by HSTDM undergoes meticulous calibration and processing through the HSTDM data processing pipeline (HSTDM pipeline for short) to ensure the accuracy and effectiveness of the final science data to be archived for further research. This process necessitates that the HSTDM pipeline address instrumental artifacts and effects as well as the coordination of data flow of the scheduled observing sequences under all observing modes of HSTDM within the CSST automated processing environment. As the understanding of CSST HSTDM data processing develops during the pipeline development stage, it becomes essential to assess the accuracy, the robustness and the performance of the HSTDM pipeline under all observing modes of HSTDM so that components of the HSTDM pipeline be rationally added, removed, amended or extended within the modular framework. In this paper, we develop practical simulation methods to facilitate this need. The contribution of synthetic data generation of HSTDM observation includes two parts: 1. HSTDM instrumental effect simulation based on both real testing profiles and simulated models; 2. Observing data flow generation based on HSTDM observing mode scenario. The simulation methods have been implemented and shown to be practical in testing the HSTDM pipeline during the development stage. △ Less

Submitted 13 November, 2025; v1 submitted 12 November, 2025; originally announced November 2025.

Comments: 22 pages, 13 figures

An XMM-Newton View of the ANdromeda Galaxy as Explored in a Legacy Survey (New-ANGELS) II: Luminosity Function of X-ray Sources

Authors: Rui Huang, Jiang-Tao Li, Wei Cui, Zhijie Qu, Joel N. Bregman, Xiang-Dong Li, Gabriele Ponti, Q. Daniel Wang

Abstract: As part of the New-ANGELS program, we systematically investigate the X-ray luminosity functions (XLFs) of 4506 X-ray sources projected within a radius of 2.5 deg centering on M31. We construct XLFs for different regions in the disk and halo of M31, accounting for the incompleteness with an effective sensitivity map. Assuming that the halo regions contain (mostly) foreground stars and background ac… ▽ More As part of the New-ANGELS program, we systematically investigate the X-ray luminosity functions (XLFs) of 4506 X-ray sources projected within a radius of 2.5 deg centering on M31. We construct XLFs for different regions in the disk and halo of M31, accounting for the incompleteness with an effective sensitivity map. Assuming that the halo regions contain (mostly) foreground stars and background active galactic nuclei, they are taken as "background" for deriving the XLFs of the sources in the disk. Through modeling XLFs, we decompose the X-ray sources into distinct populations for each region. We find that low-mass X-ray binaries are the dominant X-ray population throughout the disk of M31. The XLFs of M31 reveal a consistently lower integrated LMXB luminosity per stellar mass ($α_\mathrm{LMXB}$) compared to other galaxies, likely due to M31's prolonged period of quiescent star formation. Variations in the XLF shape and $α_\mathrm{LMXB}$ across different regions of M31 suggest that the relationship between integrated luminosity and stellar mass may vary within the galaxy. Additionally, the relatively low integrated luminosity observed in the inner-arm region provides crucial evidence for a rapid fading of M31's LMXBs around 1 Gyr, a finding consistent with recent observations of other nearby galaxies. △ Less

Submitted 8 November, 2025; originally announced November 2025.

Comments: 25 pages, 17 figures

Searching for Electromagnetic Counterpart Candidates to GW231123

Authors: Lei He, Liang-Gui Zhu, Zheng-Yan Liu, Rui Niu, Chao Wei, Bing-Zhou Gao, Ming-Shen Zhou, Run-Duo Liang, Ken Chen, Jian-Min Wang, Ning Jiang, Zhen-Yi Cai, Ji-an Jiang, Zi-Gao Dai, Ye-Fei Yuan, Jian Li, Wen Zhao

Abstract: The detection of GW231123, a gravitational-wave (GW) event with exceptionally massive and rapidly spinning black holes, suggests the possible formation within an active galactic nucleus (AGN) disk, which provides a favorable environment for potentially generating an observable electromagnetic (EM) counterpart. We conduct a search for such a counterpart by crossmatching the GW localization with a c… ▽ More The detection of GW231123, a gravitational-wave (GW) event with exceptionally massive and rapidly spinning black holes, suggests the possible formation within an active galactic nucleus (AGN) disk, which provides a favorable environment for potentially generating an observable electromagnetic (EM) counterpart. We conduct a search for such a counterpart by crossmatching the GW localization with a comprehensive catalog of AGN flares from the Zwicky Transient Facility. Our analysis yields six plausible optical flare candidates that are spatially and temporally coincident with GW231123 and exhibit significant deviations from their AGN baseline flux. Although these candidates represent a crucial first step, their true nature remains inconclusive. Confirming any one of these flares via future observations would provide a landmark validation of the AGN formation channel and unlock the multi-messenger potential of this extraordinary merger. △ Less

Submitted 7 November, 2025; originally announced November 2025.

Comments: 10 pages, 3 figures, comments are welcome

The Initial mass function of field stars with mass $\leq$ 1 $M_{\odot}$ varies with metallicity

Authors: Dan Qiu, Chao Liu, Jennifer A. Johnson, Jiadong Li, Bo Zhang

Abstract: We investigated a volume-limited sample of LAMOST main-sequence stars with masses from 0.25 to 1 $M_{\odot}$ and distances of 150-350 pc to explore how the stellar initial mass function (IMF) varies with metallicity. We corrected the spectroscopic selection function by comparing the stellar number densities with the photometric ones at the same colour and magnitude. From these corrected number den… ▽ More We investigated a volume-limited sample of LAMOST main-sequence stars with masses from 0.25 to 1 $M_{\odot}$ and distances of 150-350 pc to explore how the stellar initial mass function (IMF) varies with metallicity. We corrected the spectroscopic selection function by comparing the stellar number densities with the photometric ones at the same colour and magnitude. From these corrected number density distributions, we derived IMFs for each metallicity sub-samples. Fitting a broken power-law function in each IMF with a fixed break point at 0.525 $M_{\odot}$, we found the power-law indices increase with [Fe/H] for both mass regimes: $α_1$ (mass $\leq$ 0.525 $M_{\odot}$) rises from 0.54 $\pm$ 0.21 to 1.40 $\pm$ 0.07 and $α_2$ (mass>0.525 $M_{\odot}$) grows from 1.40 $\pm$ 0.16 to 1.86 $\pm$ 0.04 as [Fe/H] varies from -1 to +0.5 dex. It demonstrates that low-mass stars make up a larger fraction in metal-rich environments than in metal-poor ones. We performed simulations to assess the impact of unresolved binaries on the IMF power-law indices. After correction, the binary-adjusted $α$ values retained a similar metallicity-dependent trend. Furthermore, by examining the IMF of the aggregate sample, we found the corrected indices ($α_{\rm{1,corr}} = 1.48 \pm 0.03$ , $α_{\rm{2,corr}} = 2.17 \pm 0.03$) are consistent with Kroupa's IMF values ($α_1 = 1.3 \pm 0.5$ and $α_2 = 2.3 \pm 0.3$). Finally, we verified the robustness of our results by testing different break points and mass bin sizes, confirming that the IMF's dependence on [Fe/H] remains consistent. △ Less

Submitted 6 November, 2025; originally announced November 2025.

Comments: 12 pages, 13 figures

A Possible "Too-Many-Satellites" Problem in the Isolated Dwarf Galaxy DDO 161

Authors: Jiaxuan Li, Jenny E. Greene, Shany Danieli, Scott Carlsten, Marla Geha

Abstract: The abundance of satellite galaxies provides a direct test of $Λ$CDM on small scales. While satellites of Milky Way-mass galaxies are well studied, those of dwarf galaxies remain largely unexplored. We present a systematic search for satellites around the isolated dwarf galaxy DDO 161 ($M_\star \approx 10^{8.4}\, M_\odot$) at a distance of 6 Mpc. We identify eight satellite candidates within the p… ▽ More The abundance of satellite galaxies provides a direct test of $Λ$CDM on small scales. While satellites of Milky Way-mass galaxies are well studied, those of dwarf galaxies remain largely unexplored. We present a systematic search for satellites around the isolated dwarf galaxy DDO 161 ($M_\star \approx 10^{8.4}\, M_\odot$) at a distance of 6 Mpc. We identify eight satellite candidates within the projected virial radius and confirm four satellites through surface brightness fluctuation distance measurements from deep Magellan imaging data. With four confirmed satellites above $M_{\star}^{\rm sat} > 10^{5.4}\, M_\odot$, DDO 161 is the most satellite-rich dwarf galaxy known to date. We compare this system with predictions from the TNG50 cosmological simulation, combined with currently established galaxy-halo connection models calibrated on Milky Way satellites, and find that DDO 161 has a satellite abundance far exceeding all current expectations. The rich satellite system of DDO 161 offers new insight into how low-mass galaxies occupy dark matter halos in low-density environments and may provide new constraints on the nature of dark matter. △ Less

Submitted 3 November, 2025; originally announced November 2025.

Comments: 9 pages, submitted to ApJL

First Time Observed M-Shaped Coronal Mass Ejection Associated with a Blowout Jet and an Extreme Ultraviolet Wave

Authors: Yu-Hu Miao, Lin-Hua Deng, Chao-Wei Jiang, Abouazza Elmhamdi, Jiang-Tao Su, Ming-Xiang Guan, Hai-Xin Zou, Jiao-Man Li, Xue-Mei Cao, Jun-Tao Wang, Yun-Zhi Hua

Abstract: The coronal blowout jet, extreme ultraviolet (EUV) wave and coronal mass ejection (CME) are common phenomena in the solar atmosphere. In this paper, we report the occurrence of an M-shaped CME event associated with a blowout jet and an EUV wave using high-resolution, multi-angle and multi-wavelength observations taken from Solar Dynamics Observatory, and Solar TErrestrial RElations Observatory. In… ▽ More The coronal blowout jet, extreme ultraviolet (EUV) wave and coronal mass ejection (CME) are common phenomena in the solar atmosphere. In this paper, we report the occurrence of an M-shaped CME event associated with a blowout jet and an EUV wave using high-resolution, multi-angle and multi-wavelength observations taken from Solar Dynamics Observatory, and Solar TErrestrial RElations Observatory. Interestingly, and for the first time, it is found that two bubble-like CMEs and a jet-like CME were simultaneously triggered by the same eruptive event. Our observational analyses and findings indicate the following: (1) the eruption of a blowout jet led to a large-scale EUV wave; (2) the eruption of the EUV wave swept a small filament (prominence) and a long filament; (3) eventually the EUV wave split-up into two parts, leading to the two bubble-like CMEs, while the blowout jet induced a jet-like CME. The combined events appear to form an M-shape like structure CME, that we sketch throughout a proposed cartoon tentatively explaining the observed complex configuration. Based on observational diagnosis, we argue that the jet, the EUV wave and the multi-CME are highly interlinked. A suggested eruption-model, from the solar atmosphere to the space, is outlined and discussed, providing a possibly new way to probe the relationship between the solar eruptions and the surrounding space. The investigation of such rare phenomenon can be a key point for better understanding of the physical associated triggering mechanisms and energy transport in the solar atmosphere, crucial for MHD simulations and modeling. △ Less

Submitted 1 November, 2025; originally announced November 2025.

Comments: 17 pages,6 figures

The Advanced X-ray Imaging Satellite Community Science Book

Authors: Michael Koss, Nafisa Aftab, Steven W. Allen, Roberta Amato, Hongjun An, Igor Andreoni, Timo Anguita, Riccardo Arcodia, Thomas Ayres, Matteo Bachetti, Maria Cristina Baglio, Arash Bahramian, Marco Balboni, Ranieri D. Baldi, Solen Balman, Aya Bamba, Eduardo Banados, Tong Bao, Iacopo Bartalucci, Antara Basu-Zych, Rebeca Batalha, Lorenzo Battistini, Franz Erik Bauer, Andy Beardmore, Werner Becker , et al. (373 additional authors not shown)

Abstract: The AXIS Community Science Book represents the collective effort of more than 500 scientists worldwide to define the transformative science enabled by the Advanced X-ray Imaging Satellite (AXIS), a next-generation X-ray mission selected by NASA's Astrophysics Probe Program for Phase A study. AXIS will advance the legacy of high-angular-resolution X-ray astronomy with ~1.5'' imaging over a wide 24'… ▽ More The AXIS Community Science Book represents the collective effort of more than 500 scientists worldwide to define the transformative science enabled by the Advanced X-ray Imaging Satellite (AXIS), a next-generation X-ray mission selected by NASA's Astrophysics Probe Program for Phase A study. AXIS will advance the legacy of high-angular-resolution X-ray astronomy with ~1.5'' imaging over a wide 24' field of view and an order of magnitude greater collecting area than Chandra in the 0.3-12 keV band. Combining sharp imaging, high throughput, and rapid response capabilities, AXIS will open new windows on virtually every aspect of modern astrophysics, exploring the birth and growth of supermassive black holes, the feedback processes that shape galaxies, the life cycles of stars and exoplanet environments, and the nature of compact stellar remnants, supernova remnants, and explosive transients. This book compiles over 140 community-contributed science cases developed by five Science Working Groups focused on AGN and supermassive black holes, galaxy evolution and feedback, compact objects and supernova remnants, stellar physics and exoplanets, and time-domain and multi-messenger astrophysics. Together, these studies establish the scientific foundation for next-generation X-ray exploration in the 2030s and highlight strong synergies with facilities of the 2030s, such as JWST, Roman, Rubin/LSST, SKA, ALMA, ngVLA, and next-generation gravitational-wave and neutrino networks. △ Less

Submitted 31 October, 2025; originally announced November 2025.

Comments: 595 pages, 225 figures

Photometric Redshifts in JWST Deep Fields: A Pixel-Based Alternative with DeepDISC

Authors: Grant Merz, Ming-Yang Zhuang, Junyao Li, Qian Yang, Yue Shen, Xin Liu, John Franklin Crenshaw

Abstract: Photo-z algorithms that utilize SED template fitting have matured, and are widely adopted for use on high-redshift near-infrared data that provides a unique window into the early universe. Alternative photo-z methods have been developed, largely within the context of low-redshift optical surveys. Machine learning based approaches have gained footing in this regime, including those that utilize raw… ▽ More Photo-z algorithms that utilize SED template fitting have matured, and are widely adopted for use on high-redshift near-infrared data that provides a unique window into the early universe. Alternative photo-z methods have been developed, largely within the context of low-redshift optical surveys. Machine learning based approaches have gained footing in this regime, including those that utilize raw pixel information instead of aperture photometry. However, the efficacy of image-based algorithms on high-redshift, near-infrared data remains underexplored. Here, we test the performance of Detection, Instance Segmentation and Classification with Deep Learning (DeepDISC) on photometric redshift estimation with NIRCam images from the JWST Advanced Deep Extragalactic Survey (JADES) program. DeepDISC is designed to produce probabilistic photometric redshift estimates directly from images, after detecting and deblending sources in a scene. Using NIRCam-only images and a compiled catalog of spectroscopic redshifts, we show that DeepDISC produces reliable photo-zs and uncertainties comparable to those estimated from template fitting using HST+JWST filters; DeepDISC even outperforms template fitting (lower scatter/fewer outliers) when the input photometric filters are matched. Compared with template fitting, DeepDISC does not require measured photometry from images, and can produce a catalog of 94000 photo-zs in ~4 minutes on a single NVIDIA A40 GPU. While current spectroscopic training samples are small and incomplete in color-magnitude space, this work demonstrates the potential of DeepDISC for increasingly larger image volumes and spectroscopic samples from ongoing and future programs. We discuss the impact of the training data on applications to broader samples and produce a catalog of photo-zs for all JADES DR2 photometric sources in the GOOD-S field, with quality flags indicating caveats. △ Less

Submitted 30 October, 2025; originally announced October 2025.

Comments: 17 pages, 16 figures, catalog available at https://doi.org/10.5281/zenodo.17487692 code available at https://github.com/grantmerz/deepdisc

Evidence of cosmic-ray acceleration up to sub-PeV energies in the supernova remnant IC 443

Authors: Zhen Cao, F. Aharonian, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, W. Bian, A. V. Bukevich, C. M. Cai, W. Y. Cao, Zhe Cao, J. Chang, J. F. Chang, A. M. Chen, E. S. Chen, G. H. Chen, H. X. Chen, Liang Chen, Long Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. Chen, S. H. Chen , et al. (291 additional authors not shown)

Abstract: Supernova remnants (SNRs) have been considered as the primary contributors to cosmic rays (CRs) in our Galaxy. However, the maximum energy of particles that can be accelerated by shocks of SNRs is uncertain observationally and theoretically, and the role of contribution to CRs around PeV energies by SNRs is unclear. In this study, we present observations of high-energy $γ$-ray emission from the SN… ▽ More Supernova remnants (SNRs) have been considered as the primary contributors to cosmic rays (CRs) in our Galaxy. However, the maximum energy of particles that can be accelerated by shocks of SNRs is uncertain observationally and theoretically, and the role of contribution to CRs around PeV energies by SNRs is unclear. In this study, we present observations of high-energy $γ$-ray emission from the SNR IC 443 using the Large High Altitude Air Shower Observatory (LHAASO). The morphological analysis reveals a pointlike source whose location and spectrum are consistent with those of the Fermi-LAT-detected compact source with $π^0$-decay signature, and a more extended source which is consistent with a newly discovered source, previously unrecognized by Fermi-LAT. The spectrum of the point source can be described by a power-law function with an index of $\sim3.0$, extending beyond $\sim 30$ TeV without apparent cutoff. Assuming a hadronic origin of the $γ$-ray emission, the $95\%$ lower limit of accelerated protons reaches about 300 TeV. The extended source might be coincident with IC 443, SNR G189.6+3.3 or the putative pulsar wind nebula CXOU J061705.3+222127, and can be explained by either a hadronic or leptonic model. The LHAASO results provide compelling evidence that CR protons up to sub-PeV energies can be accelerated by the SNR. △ Less

Submitted 29 October, 2025; originally announced October 2025.

The Detectability of Lunar-Origin Asteroids in the LSST Era

Authors: Yixuan Wu, Yifei Jiao, Wen-Yue Dai, Yukun Huang, Zihan Liu, Bin Cheng, Hexi Baoyin, Junfeng Li

Abstract: While most near-Earth asteroids (NEAs) are thought to originate from the main belt, recent discoveries have suggested the existence of a lunar-derived NEA population, such as the asteroids Kamo'oalewa and 2024 PT5. These objects may hold key clues to the dynamical evolution of NEAs and the recent impact history of the Earth-Moon system. However, the population, distribution, and dynamical characte… ▽ More While most near-Earth asteroids (NEAs) are thought to originate from the main belt, recent discoveries have suggested the existence of a lunar-derived NEA population, such as the asteroids Kamo'oalewa and 2024 PT5. These objects may hold key clues to the dynamical evolution of NEAs and the recent impact history of the Earth-Moon system. However, the population, distribution, and dynamical characteristics of these Lunar-Origin Asteroids (LOAs) remain poorly constrained. By combining the lunar ejecta production with N-body orbital simulations of the ejecta, we investigate their orbital evolution in the past millions of years and the current LOA population, revealing their significant potential for detection by future surveys. Specifically for the Vera C. Rubin Observatory's upcoming Legacy Survey of Space and Time (LSST), we predict an average detection rate of about 6 LOAs (with D > 5 m) per year. Additionally, we find that the LOAs tend to approach from sunward and anti-sunward directions, with encounter velocities significantly lower than those of typical NEAs. These findings offer valuable insights in guiding targeted ground-based surveys and planetary defense efforts for LOAs in the future. △ Less

Submitted 27 October, 2025; originally announced October 2025.

Intruder Alert: Breaking Resonant Chains with Planetesimal Flybys

Authors: Jiaru Li, Christopher E. O'Connor, Frederic A. Rasio

Abstract: The orbital architectures of compact exoplanet systems record their complicated dynamical histories. Recent research supports the ``breaking-the-chains'' hypothesis, which proposes that compact systems typically form in chains of mean-motion resonances (MMRs) but subsequently break out on a $\sim 100$Myr timescale. We investigate a scenario for breaking the chains through intermittent flybys of pl… ▽ More The orbital architectures of compact exoplanet systems record their complicated dynamical histories. Recent research supports the ``breaking-the-chains'' hypothesis, which proposes that compact systems typically form in chains of mean-motion resonances (MMRs) but subsequently break out on a $\sim 100$Myr timescale. We investigate a scenario for breaking the chains through intermittent flybys of planetesimals originating from a distant reservoir. Using $N$-body simulations and semi-analytical calculations, we characterize the disruption of MMRs through these flybys. We find a planetesimal reservoir of total mass $\gtrsim 0.04 M_{\oplus}$ is required to disrupt MMR chains, depending on the mass distribution and the typical number of flybys executed by each planetesimal. We verify that systems disrupted in this way are frequently unstable to close encounters within $\sim 100$Myr of the final flyby. This mechanism operates in systems with both a sufficiently massive reservoir and an efficient mechanism for planetesimal injection. Consequently, we predict an anti-correlation between resonant inner systems and dynamically active outer configurations. △ Less

Submitted 21 October, 2025; originally announced October 2025.

Comments: Lead jointly by JL and CEO, 16 pages, 7 figures, 2 tables, submitted to ApJL

Improved thermonuclear rate of $^{42}$Ti($p$,$γ$)$^{43}$V and its astrophysical implication in rp-process

Authors: S. Q. Hou, C. Iliadis, M. Pignatari, J. B. Liu, T. C. L. Trueman, J. G. Li, X. X. Xu

Abstract: Accurate $^{42}$Ti($p$,$γ$)$^{43}$V reaction rates are crucial for understanding the nucleosynthesis path of the rapid capture process (rp-process) that occurs in X-ray bursts. We aim to improve the thermonuclear rates of $^{42}$Ti($p$,$γ$)$^{43}$V based on more complete resonance information and accurate direct component, together with the recently released nuclear masses data. We reevaluated the… ▽ More Accurate $^{42}$Ti($p$,$γ$)$^{43}$V reaction rates are crucial for understanding the nucleosynthesis path of the rapid capture process (rp-process) that occurs in X-ray bursts. We aim to improve the thermonuclear rates of $^{42}$Ti($p$,$γ$)$^{43}$V based on more complete resonance information and accurate direct component, together with the recently released nuclear masses data. We reevaluated the $^{42}$Ti($p$,$γ$)$^{43}$V rate by the sum of the isolated resonance contribution instead of the Hauser-Feshbach statistical model. A Monte Carlo method is used to derive the uncertainties of new rates. The nucleosynthesis simulations are performed via the NuGrid post-processing code ppn. The new rates differ from previous estimations because of using a series of updated resonance parameters and direct S-factor. Compared with the previous results from Hauser-Feshbach statistical model, which assumes compound nucleus $^{43}$V with a sufficiently high-level density in the energy region of astrophysical interest, differences exist over the entire temperature region of rp-process interest, even up to 4 orders of magnitude. Using a trajectory with a peak temperature of 1.95$\times$10$^9$ K, we perform the rp-process nucleosynthesis simulations to investigate the impact of the new rates. Our calculations show that the adoption of the new forward and reverse rates result in abundance variations for Sc and Ca by 128\% and 49\% respectively compared to the case using statistical model rates. On the other hand, the overall abundance pattern is not significantly affected. The results of using new rates also confirm that the rp-process path does not bypass the isotope $^{43}$V. It is found that the Hauser-Feshbach statistical model is inappropriate to the reaction rate evaluation for $^{42}$Ti($p$,$γ$)$^{43}$V. △ Less

Submitted 21 October, 2025; originally announced October 2025.

Comments: 7 pages, 5 figures, published in Astronomy & Astrophysics

Journal ref: Astronomy & Astrophysics, Volume 677, id.A139, 7 pp. 2023

The ALPINE-CRISTAL-JWST Survey: Stellar and nebular dust attenuation of main-sequence galaxies at z~4-6

Authors: Akiyoshi Tsujita, Seiji Fujimoto, Andreas Faisst, Meédéric Boquien, Juno Li, Andrea Ferrara, Andrew J. Battisti, Poulomi Dam, Manuel Aravena, Matthieu Béthermin, Caitlin M. Casey, Olivia R. Cooper, Steven L. Finkelstein, Michele Ginolfi, Diego A. Gómez-Espinoza, Ali Hadi, Rodrigo Herrera-Camus, Edo Ibar, Hanae Inami, Gareth C. Jones, Anton M. Koekemoer, Kotaro Kohno, Brian C. Lemaux, Ilse De Looze, Ikki Mitsuhashi , et al. (17 additional authors not shown)

Abstract: Characterizing dust attenuation is crucial for revealing the intrinsic physical properties of galaxies. We present an analysis of dust attenuation in 18 spectroscopically confirmed star-forming main-sequence galaxies at $z = 4.4-5.7$ observed with JWST/NIRSpec IFU and NIRCam, selected from the ALPINE and CRISTAL ALMA large programs. We fit the emission line fluxes from NIRSpec and the broad-band p… ▽ More Characterizing dust attenuation is crucial for revealing the intrinsic physical properties of galaxies. We present an analysis of dust attenuation in 18 spectroscopically confirmed star-forming main-sequence galaxies at $z = 4.4-5.7$ observed with JWST/NIRSpec IFU and NIRCam, selected from the ALPINE and CRISTAL ALMA large programs. We fit the emission line fluxes from NIRSpec and the broad-band photometry from NIRCam with Prospector, using both spatially integrated emission and $\sim0.6$ kpc pixel-by-pixel measurements. We derive the stellar-to-nebular dust attenuation ratio ($f=E(B-V)_{\mathrm{star}}/E(B-V)_{\mathrm{neb}}$) from the SED fits and the Balmer decrement with H$α$ and H$β$. Although individual galaxies show large scatter, the best-fit value is $f = 0.51^{+0.04}_{-0.03}$, slightly higher than that measured for local starburst galaxies. We find weak correlations of $f$ with galaxy properties, increasing with higher specific star-formation rates, younger stellar ages, and more recent star-formation. For the range of $E(B-V)_{\mathrm{star}} = 0.009-0.15$ mag for in our sample, assuming $f = 1$ (often adopted in high-redshift studies) instead of $f = 0.51$ underestimate line luminosities and ionizing photon production efficiency $ξ_\text{ion}$ by $\sim3-36\%$ and $\sim4-46\%$, respectively. We also find that the total stellar masses estimated from spatially-integrated SED fits with a delayed-$τ$ star-formation histories are systematically smaller than the sum of pixel-by-pixel SED fits, with a median offset of $\sim 0.26$ dex, likely because the integrated fits are biased toward luminous young stellar populations. △ Less

Submitted 19 November, 2025; v1 submitted 20 October, 2025; originally announced October 2025.

Comments: Accepted for publication in ApJ. 23 pages and 7 figures. See also the companion "The ALPINE-CRISTAL-JWST Survey" papers by Faisst et al. and Fujimoto et al

Testing the Stellar Feedback-driven Breathing Mode in Low-mass Galaxies with Gas Kinematics

Authors: Yifei Luo, Joseph Wick, Alexie Leauthaud, Andrew Wetzel, Tucker Jones, Erin Kado-Fong, Song Huang, Xinjun Chen, Conghao Zhou, Jiaxuan Li

Abstract: Hydrodynamic simulations have proposed that stellar feedback and bursty star-formation can produce dark matter cores in low-mass galaxies. A key prediction is that feedback-driven gas outflow and inflow cycles can lead to ``breathing modes'' (rapid fluctuations in the global gravitational potential) which drive correlated variations in galaxy size, kinematics, and star-formation rate. In this pape… ▽ More Hydrodynamic simulations have proposed that stellar feedback and bursty star-formation can produce dark matter cores in low-mass galaxies. A key prediction is that feedback-driven gas outflow and inflow cycles can lead to ``breathing modes'' (rapid fluctuations in the global gravitational potential) which drive correlated variations in galaxy size, kinematics, and star-formation rate. In this paper, we test the dynamical effects of feedback-driven breathing modes using a sample of 103 star-forming low-mass galaxies with stellar masses between $7.9<\rm \log M_*/M_\odot<9.6$ and $0.02<z<0.19$. We measure ionized gas velocity dispersions from H$α$ emission lines and compare them to mock observations from the FIRE-2 simulations. We compare gas velocity dispersions ($\rm σ_{gas}$), stellar masses, and specific star-formation rates (sSFR). We find a positive correlation between gas velocity dispersion residuals at fixed stellar masses ($\rm Δσ_{gas}$) and sSFR in both data and simulations. However, the relation is tighter in FIRE-2 compared to the data. FIRE-2 produces more low-sSFR galaxies compared to our observational sample, however, the sSFR distributions agree after limiting both samples to a minimum sSFR. A deeper and more complete photometric sample further indicates that observed low-mass galaxies could span the full range of sSFR predicted in the FIRE-2 simulations. Our results support the existence of short-timescale dynamical effects driven by gas outflow and inflow cycles in low-mass galaxies and motivate additional tests of the breathing mode. △ Less

Submitted 20 October, 2025; originally announced October 2025.

Comments: 23 pages, 12 figures

The Silent Majority: The Interacting Post-Common-Envelope Binaries Underlying Cataclysmic Variables

Authors: Yarin Meir Shani, Na'ama Hallakoun, Sagi Ben-Ami, Sahar Shahaf, Jiadong Li, Hans-Walter Rix, Silvia Toonen

Abstract: We analyze the orbital period distribution of post-common-envelope white-dwarf-main-sequence (WDMS) binaries by cross-matching the new spectroscopic Gaia DR3 WDMS catalog with TESS light curves, and applying a uniform periodicity search and vetting pipeline. We identify 107 periodic systems, including 74 eclipsing binaries (32 new) and 33 binaries exhibiting only sinusoidal variations. Injection-r… ▽ More We analyze the orbital period distribution of post-common-envelope white-dwarf-main-sequence (WDMS) binaries by cross-matching the new spectroscopic Gaia DR3 WDMS catalog with TESS light curves, and applying a uniform periodicity search and vetting pipeline. We identify 107 periodic systems, including 74 eclipsing binaries (32 new) and 33 binaries exhibiting only sinusoidal variations. Injection-recovery tests and a forward detectability model yield a completeness-corrected distribution that is well-described by a two-component function: a log-period Gaussian peaking at $P_{\rm orb} \approx 4.1 $ h with $σ\approx 1.8$ h, plus a rising component that begins near $P_{\rm orb}\approx12.9$ h. We refer to this extended component as the long-period tail. It consists exclusively of detached non-interacting post-common-envelope binaries (PCEBs) that likely emerged from the common envelope and have not yet initiated mass transfer. In contrast, the short-period Gaussian is dominated by interacting or near-contact systems (including 22 known cataclysmic variables), consistent with high Roche-lobe filling factors. From the completeness-corrected distribution we infer that $29.8\%\pm4.5\%$ of the spatially unresolved WDMSs in our parent catalog are close PCEBs. Binary population synthesis models with high common-envelope efficiencies overproduce long-period systems and fail to reproduce the sharp peak, whereas lower efficiencies ($αλ\leq 0.3$) match the peak more closely, yet still underpredict the tail. Our results hint at a large, currently under-classified reservoir of pre-cataclysmic variables and weakly accreting binaries, and provide new constraints on common-envelope physics. △ Less

Submitted 20 October, 2025; originally announced October 2025.

Reconnection-driven Decaying Pulsations Modulated by Slow Magnetoacoustic Waves

Authors: Dong Li, Jianping Li, Haisheng Ji

Abstract: Decaying pulsations have been simultaneously detected in the low-energy X-rays of solar/stellar flares, which are supposed to be associated with standing slow magnetoacoustic or kink-mode waves. The physical mechanism behind rapidly decaying remains unknown. We present the detection of quasi-periodic pulsations (QPPs) with rapidly decaying in high-energy emissions produced in two major flares on 1… ▽ More Decaying pulsations have been simultaneously detected in the low-energy X-rays of solar/stellar flares, which are supposed to be associated with standing slow magnetoacoustic or kink-mode waves. The physical mechanism behind rapidly decaying remains unknown. We present the detection of quasi-periodic pulsations (QPPs) with rapidly decaying in high-energy emissions produced in two major flares on 10 January and 14 May 2024. Using empirical mode decomposition, decaying QPPs are identified in hard X-ray and microwave emissions during the flare impulsive phase, suggesting a process of oscillatory magnetic reconnection. The quasi-periods and decay times are determined by a damped harmonic function, which are approximately 177$\pm$8 s (249$\pm$25 s) and 118$\pm$4 s (124$\pm$5 s), respectively. The restructured X-ray images reveal double footpoints connected by hot flare loops. Their phase speeds are estimated to about 400 km/s and 670 km/s, both below the local sound speed in high-temperature plasmas, indicating the presence of slow-mode waves in hot flare loops. We perform coronal diagnostics based on standing slow-mode waves and derive key physical parameters, including the polytropic index, the thermal ratio, viscous ratio and radiation ratio, which are consistent with previous results. Our observations support that the decaying QPPs are triggered by oscillatory magnetic reconnection that is modulated by standing slow magnetoacoustic waves, with their rapid decay attributable to a co-effect of viscous damping and localized magnetic reconnection rate. △ Less

Submitted 19 October, 2025; originally announced October 2025.

Comments: accepted for publication in ApJS

CO in MASsive Spirals (CO-MASS): an IRAM 30m CO emission line survey of the CGM-MASS sample

Authors: Yu Huang, Jiangtao Li, Yan Jiang, Ping Zhou, Jianghui Xu, Liyuan Lu, Yang Yang

Abstract: There exist extremely massive spiral galaxies in isolated environments, with stellar masses several times that of the Milky Way, yet their star formation rates (SFRs) are comparable to or even lower than that of the Milky Way. In this paper, we investigate the molecular gas properties of such galaxies to better understand the origin of their low SFRs. We present IRAM 30m CO observations of five ex… ▽ More There exist extremely massive spiral galaxies in isolated environments, with stellar masses several times that of the Milky Way, yet their star formation rates (SFRs) are comparable to or even lower than that of the Milky Way. In this paper, we investigate the molecular gas properties of such galaxies to better understand the origin of their low SFRs. We present IRAM 30m CO observations of five extremely massive spirals from the CGM-MASS sample. We compare their star formation efficiencies (SFEs) with the Kennicutt-Schmidt relation and find that these massive spirals generally exhibit low efficiency in converting molecular gas into stars. We further compare their molecular gas masses with their atomic gas and stellar masses, and also include the CHANG-ES sample galaxies observed with the IRAM 30m telescope in a similar manner for comparison. Our sample galaxies show low efficiency in converting atomic to molecular gas and have lower molecular gas fractions, suggesting that their suppressed star formation stems from both limited gas supply and inefficient star formation. Considering potential cold gas sources in massive spirals, we argue that their current reservoirs likely originate from past starburst or merger events rather than ongoing accretion in present isolated environments. Finally, we examine the location of these galaxies on the baryonic Tully-Fisher relation, finding them baryon-deficient and deviating from the trend of lower-mass galaxies. This suggests either a significant undetected baryonic component or a flattening/turnover of the relation at the high-mass end, consistent with the stellar mass-halo mass relation. △ Less

Submitted 18 October, 2025; originally announced October 2025.

Investigating Production of TeV-scale Muons in Extensive Air Shower at 2400 Meters Underground

Authors: Xinshun Zhang, Shaomin Chen, Wei Dou, Haoyang Fu, Lei Guo, Ziyi Guo, XiangPan Ji, Jianmin Li, Jinjing Li, Bo Liang, Ye Liang, Qian Liu, Wentai Luo, Ming Qi, Wenhui Shao, Haozhe Sun, Jian Tang, Yuyi Wang, Zhe Wang, Changxu Wei, Jun Weng, Yiyang Wu, Benda Xu, Chuang Xu, Tong Xu , et al. (8 additional authors not shown)

Abstract: The China Jinping Underground Laboratory, characterized by a vertical rock overburden of 2,400 m, provides an exceptionally effective shield against cosmic muons with energies below 3 TeV. The surviving high-energy muons, produced as part of extensive air showers, open a unique observational window into primary cosmic rays with energies ranging from tens of TeV up to the PeV scale and beyond. This… ▽ More The China Jinping Underground Laboratory, characterized by a vertical rock overburden of 2,400 m, provides an exceptionally effective shield against cosmic muons with energies below 3 TeV. The surviving high-energy muons, produced as part of extensive air showers, open a unique observational window into primary cosmic rays with energies ranging from tens of TeV up to the PeV scale and beyond. This distinctive feature also enables detailed studies of the earliest stages of shower development. Using 1,338.6 live days of data collected with a one-ton prototype detector for the Jinping Neutrino Experiment, we measured the underground muon flux originating from air showers. The results show discrepancies of about 40%, corresponding to a significance of more than 5.5$σ$, relative to predictions from several leading hadronic interaction models. We interpret these findings from two complementary perspectives: (i) by adopting the expected cosmic ray spectra, we constrain the modeling of the initial hadronic interactions in air showers; and (ii) by assuming specific hadronic interaction models, we infer the mass composition of cosmic rays, and our data favor a lighter component in the corresponding energy range. Our study demonstrates the potential of deep underground laboratories to provide new experimental insights into cosmic rays. △ Less

Submitted 18 October, 2025; originally announced October 2025.

Comments: 7 pages; 5 figures

Antarctic Infrared Binocular Telescope. I. System Overview, Laboratory Testing, and On-Sky Performance Evaluation

Authors: Zhongnan Dong, Bin Ma, Haoran Zhang, Jinji Li, Xu Yang, Yi Hu, Zhaohui Shang, Michael C. B. Ashley

Abstract: Infrared time-domain surveys remain significantly underdeveloped compared with their optical counterparts. We have developed the Antarctic Infrared Binocular Telescope (AIRBT) to study the dynamic infrared sky at Dome A, Antarctica, taking advantage of the superb infrared observational conditions at this site. AIRBT consists of two identical 15 cm f/3 optical tube assemblies and two cost-effective… ▽ More Infrared time-domain surveys remain significantly underdeveloped compared with their optical counterparts. We have developed the Antarctic Infrared Binocular Telescope (AIRBT) to study the dynamic infrared sky at Dome A, Antarctica, taking advantage of the superb infrared observational conditions at this site. AIRBT consists of two identical 15 cm f/3 optical tube assemblies and two cost-effective indium gallium arsenide (InGaAs) cameras equipped with J and H filters, respectively. The cameras have 640 x 512 pixels with a size of 15 micrometers, providing a scale of 6.9 arcseconds per pixel and a field of view of 1.22 x 0.97 square degrees. We characterize the performance of the InGaAs cameras, including bias, readout noise, dark current, nonlinearity, and photon transfer curve. Our analysis highlights the distinct behaviors of InGaAs cameras compared with charge-coupled devices (CCDs). The bias and readout noise show temperature dependence, and the noise measured from the photon transfer curves has additional components that increase with exposure time. On-sky tests were conducted in October 2022 including system calibration, limiting depth, and photometric precision. For a single 3-second exposure, we achieved 5-sigma limiting magnitudes of 11.2 mag (Vega system) in J band and 9.7 mag in H band. The best photometric precision reached 20 millimagnitudes at the bright end, which could be further improved to sub-percent levels through image stacking. AIRBT was installed at Dome A in January 2023, and scientific observations began as soon as darkness set in. △ Less

Submitted 16 October, 2025; originally announced October 2025.

Widespread Hot Molecular Gas Heated by Shear-induced Turbulence in the Galactic Center

Authors: Juan Li, Junzhi Wang, Zhiqiang Shen, Alba Vidal-Garcia, Yuqiang Li, DI Li, Liubin Pan, Lei Huang, Fengyao Zhu, Siqi Zheng, Yiping Ao, Alvaro Sanchez-Momge, Zhiyu Zhang, Xing Lu, Tie Liu, Xingwu Zheng

Abstract: We observed NH3 metastable inversion lines from (3, 3) to (18, 18) toward G0.66-0.13 in the Galactic center with the Shanghai Tianma 65m radio telescope and Yebes 40 m telescope. Highly-excited lines of NH3 (17, 17), (18, 18) were detected in emission for the first time in the interstellar medium, with upper energy levels up to 3100 K. Mapping observations reveal widespread hot molecular gas trace… ▽ More We observed NH3 metastable inversion lines from (3, 3) to (18, 18) toward G0.66-0.13 in the Galactic center with the Shanghai Tianma 65m radio telescope and Yebes 40 m telescope. Highly-excited lines of NH3 (17, 17), (18, 18) were detected in emission for the first time in the interstellar medium, with upper energy levels up to 3100 K. Mapping observations reveal widespread hot molecular gas traced by NH3 (13, 13) toward G0.66-0.13. The rotation temperatures of hot gas traced by NH3 exceed 400 K, which amounts to five percent of the total NH3 in the Galactic Center. Hot gas (>400 K) and warm gas (100-140 K) are found in distinct clumps, with the hot gas located at the interfacing regions between different warm clouds. The theory of intermittency in turbulence reproduces the complex temperature structure in the central molecular zone, especially the hot gas observed here. The results presented here demonstrate that turbulence heating dominates the heating of the molecular gas in the Central Molecular Zone, while the turbulence is induced by the shear-motion of molecular clouds under the gravitational potential of the nuclear star clusters and the supermassive black hole. Our results suggest that shear-induced turbulence heating could be a widespread factor influencing galactic evolution. △ Less

Submitted 14 October, 2025; originally announced October 2025.

Comments: 21 pages, 7 figures. Accepted by ApJ

Rotation of Polarization Angle in Gamma-Ray Burst Prompt Phase. III. The Influence of the Magnetic Field Orientation

Authors: Xing-Yao Wang, Jia-Sheng Li, Mi-Xiang Lan

Abstract: Polarization is very sensitive to the configuration of the magnetic field in the radiation region. In addition to polarization curve and polarization spectrum, studies of polarization angle (PA) rotation spectrum is also crucial. In this paper, we use a simple parametric magnetic reconnection model with a large-scale aligned magnetic field in the radiation region to study the effects of field orie… ▽ More Polarization is very sensitive to the configuration of the magnetic field in the radiation region. In addition to polarization curve and polarization spectrum, studies of polarization angle (PA) rotation spectrum is also crucial. In this paper, we use a simple parametric magnetic reconnection model with a large-scale aligned magnetic field in the radiation region to study the effects of field orientation on the PA rotations. Under different field orientations, variations of the PA rotation with parameters and the PA rotation spectra are studied. We find that the conclusions obtained in our previous works are almost independent of the field orientations. The area of the parameter space with $Δ$PA $>10^\circ$ will shrink as the value of field orientation ($δ$) increases for $0^\circ<δ<90^\circ$. The $Δ$PA values would be the same for two complementary field orientations. For two particular magnetic field orientations ($δ=0^\circ$ and $90^\circ$), the $Δ$PA would also only be $0^\circ$ or $90^\circ$ within the burst duration. △ Less

Submitted 13 October, 2025; originally announced October 2025.

Comments: 9 pages, 2 figures, 1 table, ApJ accepted

Spin and Obliquity Distributions of Low-mass Planets Shaped by Dynamical Instability

Authors: Dieran Wang, Jiaru Li, Dong Lai

Abstract: Exoplanetary systems hosting multiple low-mass planets are thought to have experienced dynamical instability, during which planet-planet collisions and mergers occur; these collisions can impart substantial amount of angular momentum to the merger remnants, changing the obliquities of the resulting planets significantly. In this work, we carry out a series of $N$-body experiments to investigate th… ▽ More Exoplanetary systems hosting multiple low-mass planets are thought to have experienced dynamical instability, during which planet-planet collisions and mergers occur; these collisions can impart substantial amount of angular momentum to the merger remnants, changing the obliquities of the resulting planets significantly. In this work, we carry out a series of $N$-body experiments to investigate the spin magnitude $(|\vec{S}|)$ and obliquity $(θ_{\rm SL})$ distributions of low-mass exoplanets that have gone through planetary collisions. In our fiducial super-Earth (with $m=3M_{\oplus}$, $R=1.3R_{\oplus}$) and mini-Neptune systems (with $m=9M_{\oplus}$, $R=2.5R_{\oplus}$), the collision products follow a nearly uniform distribution in $\cos{θ_{\rm SL}}$ and the spin-magnitude distribution is approximately linear in $|\vec{S}|$. Parameter studies and theoretical analysis show that increasing planetary radii or masses, or decreasing the initial planet-planet mutual inclinations, tend to polarize the obliquity distribution toward alignment or anti-alignment (i.e., excess probability near $\cos{θ_{\rm SL}}=\pm1$). Experiments with initially two-planet and three-planet systems produce qualitatively similar outcomes, suggesting that the trends in this study may generalize to systems with higher planetary multiplicities. △ Less

Submitted 13 October, 2025; originally announced October 2025.

Comments: 10 pages, 6 figures, 1 table, submitted to ApJ

The PHANGS-MUSE/HST-Halpha Nebulae Catalogue

Authors: A. T. Barnes, R. Chandar, K. Kreckel, F. Belfiore, D. Pathak, D. Thilker, A. K. Leroy, B. Groves, S. C. O. Glover, R. McClain, A. Amiri, Z. Bazzi, M. Boquien, E. Congiu, D. A. Dale, O. V. Egorov, E. Emsellem, K. Grasha, J. Gonzalez Lobos, K. Henny, H. He, R. Indebetouw, J. C. Lee, J. Li, F. -H. Liang , et al. (16 additional authors not shown)

Abstract: We present the PHANGS-MUSE/HST-Halpha nebulae catalogue, comprising 5177 spatially resolved nebulae across 19 nearby star-forming galaxies (< 20 Mpc), based on high-resolution Halpha imaging from HST, homogenised to a fixed 10 pc resolution and sensitivity. Combined with MUSE spectroscopy, this enables robust classification of 4882 H II regions and separation of planetary nebulae and supernova rem… ▽ More We present the PHANGS-MUSE/HST-Halpha nebulae catalogue, comprising 5177 spatially resolved nebulae across 19 nearby star-forming galaxies (< 20 Mpc), based on high-resolution Halpha imaging from HST, homogenised to a fixed 10 pc resolution and sensitivity. Combined with MUSE spectroscopy, this enables robust classification of 4882 H II regions and separation of planetary nebulae and supernova remnants. Electron densities for 2544 H II regions are derived using [S II] diagnostics, and nebular sizes measured via circularised radii and second moments yield a median of 20 pc, extending to sub-parsec scales. A structural complexity score traces substructure, showing that about a third of regions are H II complexes, with a higher fraction in galaxy centres. A luminosity-size relation calibrated from the HST sample is applied to 30,790 MUSE nebulae, recovering sizes down to 1 pc. Observed sizes exceed classical Stromgren radii, implying typical volume filling factors of 0.22. We associate 3349 H II regions with stellar populations from PHANGS-HST, finding median ages of 3 Myr and masses of 4-5 log(Msun). The dataset provides a detailed, spatially resolved link between nebular structure and ionising sources, serving as a benchmark for future studies of feedback, diffuse ionised gas, and star formation regulation in the interstellar medium. The full catalogue is made publicly available in machine-readable format. △ Less

Submitted 13 October, 2025; originally announced October 2025.

Comments: 16 (+10) pages, 14 (+7) figures, 1 (+7) tables, accepted for publication in A&A, full catalogue available via CDS

Slitless Spectroscopy Source Detection Using YOLO Deep Neural Network

Authors: Xiaohan Chen, Man I Lam, Yingying Zhou, Hongrui Gu, Jinzhi Lai, Zhou Fan, Jing Li, Xin Zhang, Hao Tian

Abstract: Slitless spectroscopy eliminates the need for slits, allowing light to pass directly through a prism or grism to generate a spectral dispersion image that encompasses all celestial objects within a specified area. This technique enables highly efficient spectral acquisition. However, when processing CSST slitless spectroscopy data, the unique design of its focal plane introduces a challenge: photo… ▽ More Slitless spectroscopy eliminates the need for slits, allowing light to pass directly through a prism or grism to generate a spectral dispersion image that encompasses all celestial objects within a specified area. This technique enables highly efficient spectral acquisition. However, when processing CSST slitless spectroscopy data, the unique design of its focal plane introduces a challenge: photometric and slitless spectroscopic images do not have a one-to-one correspondence. As a result, it becomes essential to first identify and count the sources in the slitless spectroscopic images before extracting spectra. To address this challenge, we employed the You Only Look Once (YOLO) object detection algorithm to develop a model for detecting targets in slitless spectroscopy images. This model was trained on 1,560 simulated CSST slitless spectroscopic images. These simulations were generated from the CSST Cycle 6 and Cycle 9 main survey data products, representing the Galactic and nearby galaxy regions and the high galactic latitude regions, respectively. On the validation set, the model achieved a precision of 88.6% and recall of 90.4% for spectral lines, and 87.0% and 80.8% for zeroth-order images. In testing, it maintained a detection rate >80% for targets brighter than 21 mag (medium-density regions) and 20 mag (low-density regions) in the Galactic and nearby galaxies regions, and >70% for targets brighter than 18 mag in high galactic latitude regions. △ Less

Submitted 12 October, 2025; originally announced October 2025.

Comments: 22 pages, 11 figures, 7 tables. PASP accepted

Beamforming in Interferometer Arrays with Cross-couplings

Authors: Yingfeng Liu, Shijie Sun, Kaifeng Yu, Furen Deng, Shifan Zuo, Jixia Li, Yougang Wang, Fengquan Wu, Xuelei Chen

Abstract: For an interferometric array, an image of the sky can be synthesized from interferometric visibilities, which are the cross-correlations of the received electric voltages of pairs of array elements. However, to search for transient targets such as the fast radio burst (FRB), it is more convenient to use the beam-forming technique, where the real-time voltage outputs of the array elements are used… ▽ More For an interferometric array, an image of the sky can be synthesized from interferometric visibilities, which are the cross-correlations of the received electric voltages of pairs of array elements. However, to search for transient targets such as the fast radio burst (FRB), it is more convenient to use the beam-forming technique, where the real-time voltage outputs of the array elements are used to generate data streams (beams) which are sensitive to a specific direction. This is usually achieved by a weighted sum of the array element voltages, with the complex weight adjusted so that all outputs have the same phase for that direction. Alternatively, beams can also be formed from the weighted sum of the short time averaged correlation (visibility) data. We shall call these two approaches the electric voltage beam forming (EBF) and cross-correlation beam forming (XBF), respectively. All beams formed with the EBF can also be formed by the XBF method, but the latter can also generate beams which can not be generated by the former. We discuss the properties of these two kinds of beams, and the amount of computation required in each case. For an array with large number of elements, the XBF would require much more computation resource, although this is partly compensated by the fact that it allows integration over time. We study the impact of cross-coupling between array elements on the beamforming, first using a toy model, then for the case of the Tianlai Cylinder Pathfinder Array. In both cases, we find that the impact of the cross-coupling on the beam profile is relatively small. The understanding gained in this study is helpful in designing and understanding the beam-forming FRB digital backend for compact arrays such as the Tianlai array. △ Less

Submitted 11 October, 2025; originally announced October 2025.

Comments: 18 pages, 12 figures, RAA accepted

A New Algol-type Binary with an Accretion disk

Authors: Tongyu He, Jiao Li, Xiaobin Zhang, Mikhail Kovalev, Zhibin Dai, Zhenwei Li, Hongwei Ge, Shunyi Lan, Jiangdan Li, Dengkai Jiang, Jianping Xiong, Xuefei Chen, Zhanwen Han

Abstract: We present a comprehensive photometric and spectroscopic analysis of the Algol-type binary \textit{Gaia} DR3 1892576067672499328. We identified the system as a spectroscopic binary based on medium-resolution LAMOST spectra. Combined with \textit{TESS} photometry, we determine an orbital period of \( P = 2.47757 (1) \) days, a low mass ratio of \( q = 0.098 \pm 0.002 \), and an orbital inclination… ▽ More We present a comprehensive photometric and spectroscopic analysis of the Algol-type binary \textit{Gaia} DR3 1892576067672499328. We identified the system as a spectroscopic binary based on medium-resolution LAMOST spectra. Combined with \textit{TESS} photometry, we determine an orbital period of \( P = 2.47757 (1) \) days, a low mass ratio of \( q = 0.098 \pm 0.002 \), and an orbital inclination of \( i = 46.934^{+2.613}_{-1.11} \) degrees. The orbit is consistent with being circular (\( e = 0 \)). The binary comprises a \( M_1 = 1.817 ^{ +0.106}_{-0.202} \,M_\odot \), \( R_1 = 1.265^{+0.121}_{-0.160}\,R_\odot \) A-type primary and a Roche-lobe-filling secondary of \( M_2 = 0.179 ^{ +0.011}_{-0.020} \,M_\odot \), \( R_2 = 1.994 ^{ +0.041}_{-0.077} \,R_\odot \). The double-peak H$α$ emission line indicates the possible existence of a Keplerian accretion disc. We established a simple standard accretion disc model and modeled the geometric and dynamical properties of the accretion disc. The obtained outer disc radius $R_{\mathrm{out}} \approx 3.36 \pm 0.43\,R_\odot$ is consistent with the values inferred from the emission velocity of H$α$. Systemic velocity variations observed over time suggest the possible presence of a tertiary companion, with a minimum mass of $M_3 > 0.369 \pm 0.024 \,M_\odot$. Given the low mass ratio, the secondary may evolve into a proto-helium white dwarf, forming an \text{EL CVn}-type system in the future. This system offers valuable insights into accretion dynamics and the formation of binaries. △ Less

Submitted 8 October, 2025; originally announced October 2025.

A Giant Peanut-shaped Ultra-High-Energy Gamma-Ray Emitter Off the Galactic Plane

Authors: Zhen Cao, Felix Aharonian, Yunxiang Bai, Yiwei Bao, Denis Bastieri, Xiaojun Bi, YuJiang Bi, Mr Bian WenYi, A. Butkevich, Chengmiao Cai, Wenyu Cao, Zhe Cao, Jin Chang, Jinfan Chang, Mr Aming Chen, Ensheng Chen, Mr Guo-Hai Chen, Mr Huaxi Chen, Liang Chen, Long Chen, Mingjun Chen, Mali Chen, Qihui Chen, Shi Chen, Suhong Chen , et al. (291 additional authors not shown)

Abstract: Ultra-high-energy (UHE), exceeding 100 TeV (10^12 electronvolts), γ-rays manifests extreme particle acceleration in astrophysical sources. Recent observations by γ-ray telescopes, particularly by the Large High Altitude Air Shower Observatory (LHAASO), have revealed a few tens of UHE sources, indicating numerous Galactic sources capable of accelerating particles to PeV (10^15 electronvolts) energi… ▽ More Ultra-high-energy (UHE), exceeding 100 TeV (10^12 electronvolts), γ-rays manifests extreme particle acceleration in astrophysical sources. Recent observations by γ-ray telescopes, particularly by the Large High Altitude Air Shower Observatory (LHAASO), have revealed a few tens of UHE sources, indicating numerous Galactic sources capable of accelerating particles to PeV (10^15 electronvolts) energies. However, discerning the dominant acceleration mechanisms (leptonic versus hadronic), the relative contributions of specific source classes, and the role of particle transport in shaping their observed emission are central goals of modern UHE astrophysics. Here we report the discovery of a giant UHE γ-ray emitter at -17.5° off the Galactic plane - a region where UHE γ-ray sources are rarely found. The emitter exhibits a distinctive asymmetric shape, resembling a giant "Peanut" spanning 0.45° \times 4.6°, indicative of anisotropic particle distribution over a large area. A highly aged millisecond pulsar (MSP) J0218+4232 is the sole candidate accelerator positionally coincident with the Peanut region. Its association with UHE γ-rays extending to 0.7 PeV, if confirmed, would provide the first evidence of a millisecond pulsar powering PeV particles. Such a finding challenges prevailing models, which posit that millisecond pulsars cannot sustain acceleration to PeV energies. The detection reveals fundamental gaps in understanding particle acceleration, cosmic-ray transport, and interstellar magnetic field effects, potentially revealing new PeV accelerator (PeVatron) classes. △ Less

Submitted 25 October, 2025; v1 submitted 8 October, 2025; originally announced October 2025.