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宇宙工学・惑星科学・宇宙物理の最新プレプリント。

astro-ph.HEastro-ph.SR

High-mass binary black hole mergers from detailed binary evolution models

Max M. Briel, Olcay Bıyıklı, Tassos Fragos, Anarya Ray, Zepei Xing, Monica Gallegos-Garcia, Abhishek Chattaraj, Jeff J. Andrews et al.

Gravitational-wave observations reveal a population of binary black hole (BBH) mergers with primary masses above ${\sim}40\,\mathrm{M}_\odot$, extending into and potentially beyond the pair-instability mass gap, with a possibly flat mass-ratio and broader χ_\mathrm{eff} distribution. We investigate whether super-Eddington accretion during stable mass transfer in isolated binary evolution can produce BBH mergers consistent with these properties across primary BH mass, mass-ratio, and χ_\mathrm{ef…

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astro-ph.SR

SRG/eROSITA X-ray selected cataclysmic variable candidates observed in SDSS-V DR20

J. Brink, A. D. Schwope, K. G. Pradeep, T. Dwelly, S. F. Anderson, C. Andonie, S. Aviram, C. Aydar et al.

We report on the spectroscopic observations obtained during SDSS-V DR20 of accreting compact binaries (ACB), specifically the cataclysmic variables (CVs), that were identified as likely compact binary candidates from the SRG (Spectrum Roentgen Gamma) eROSITA eRASS1 and eRASS:3 observations. Our primary aim is to obtain a complete inventory of all CVs that were detected in eRASS1 and eRASS:3, with the goal to help better understand close-binary evolution, the population density, and demographics…

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astro-ph.SR

The Study of Quasi-Periodic Pulsations in Solar and Stellar Flares with SKA

Valery M. Nakariakov, Atul Mohan, Vishal Upendran, Teresa Monsue, Hamish A. S. Reid, Dmitrii Y. Kolotkov, Sergey A. Belov, Kyung-Suk Cho et al.

An intensively studied phenomenon which is not described by the standard flare model are quasi-periodic pulsations (QPP) of the flaring emission. As analysis of the QPP phenomenon intrinsically requires a combination of high time and spatial resolutions, especially in the radio band, the unprecedented capabilities of SKA offer us a unique opportunity to reach a breakthrough progress in the observational study of QPP. The SKA-Mid-frequency band falls in a unique window where both coherent emissio…

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astro-ph.IM

DM/WFS mis-registration tracking: Implementation and on-sky validation of SPRINT at LBT

Ben Buky, Cédric Taïssir Héritier, Fabio Rossi, Juan Carlos Guerra, Charlotte Z. Bond, Noah Schwartz, Guido Agapito, Enrico Pinna et al.

The advent of telescopes with an integrated deformable mirror (DM) presents new challenges for adaptive optics (AO) systems. The alignment between the DM and wavefront sensor (WFS) is expected to regularly evolve during operations due to their large separation. Without tracking and correction, these mis-registrations between the DM and WFS lead to loop instability, preventing diffraction limited performance from being realised. SPRINT\cite{heritier2021} provides an approach to track these mis-re…

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astro-ph.GA

The eROSITA X-ray luminosity function of active galactic nuclei

W. Roster, J. Buchner, M. Salvato, R. Shirley, A. Merloni, T. Dwelly, J. Aird, A. Georgakakis et al.

The X-ray luminosity function (XLF) of active galactic nuclei (AGN) provides an observational probe of the growth of supermassive black holes (SMBHs) across cosmic time. With its large survey grasp, Spectrum Roentgen Gamma (SRG)/eROSITA samples the luminosity--redshift plane with a depth--area balance complementary to pencil-beam surveys, providing the volume needed to detect rare luminous AGN, previously limited by small-number statistics. We measure the soft XLF, leveraging an eROSITA sample s…

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hep-thastro-ph.HEgr-qchep-ph

Non-conformal obstructions to bubble expansion

David Mateos, Mikel Sanchez-Garitaonandia, Pedro Tarancón-Álvarez

We investigate the hydrodynamics of expanding bubbles in first-order phase transitions with non-conformal thermodynamics. We analyze a broad class of equations of state interpolating between bag-model descriptions, commonly used for electroweak transitions, and QCD-like theories. As a concrete benchmark, we determine the bubble solutions for pure SU(3) Yang-Mills theory. We uncover a new set of hydrodynamic obstructions to bubble expansion. These obstructions arise both at the bubble wall and al…

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astro-ph.HEgr-qchep-phhep-th

Thermal Breaking of the I-Love Universality for Hot White Dwarfs

Jinyi Lv, Jing-Yi Wu, Hongji Chen, Kexin Jia, Weihan Sun, Kilar Zhang

The universal I-Love-Q relations for compact stars have significant applications in gravitational-wave astronomy, but thermal effects can break these relations in low-mass white dwarfs. In this work, we employ the stellar evolution code MESA to construct realistic models of $0.15 \, M_{\odot}$ helium-core and $0.6 \, M_{\odot}$ carbon-oxygen core white dwarfs at various temperatures. By utilizing the Clairaut-Radau equation, we quantitatively extract the radial variation of the eccentricity of i…

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physics.space-phastro-ph.EP

Ranking the drivers of the Venusian bow shock and ion composition boundary locations

Philippe Garnier, Moa Persson, Sofia Bergman, Yoshifumi Futaana

The Venusian interaction with the solar wind leads to the formation of an induced magnetosphere structured by plasma boundaries. Their dynamics is complex, due to the combined influence of external (solar photons, solar wind plasma and interplanetary magnetic field (IMF)) and internal (ionized atmosphere) drivers. Studying these drivers helps understanding the transfer of energy and momentum throughout the Venusian system, and has thus implications for the erosion of the atmosphere through its c…

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astro-ph.GA

Revealing the Physical Driver of the Baldwin Effect: Gas Density in the Broad-Line Region

Wen-Qiang Liang, Zhi-Fu Chen, Rui-Jing Lu, Cheng-Feng Peng, Shao-Hua Zhang, Zhe-Geng Chen, Zhi-Qing Chen, Yi-Qi Chen et al.

The Baldwin effect --- the inverse correlation between the equivalent width of emission lines and the continuum luminosity in active galactic nuclei (AGNs) --- has been known for nearly five decades, yet its physical origin remains poorly understood. Using a sample of 41,159 radio quasars constructed from the Sloan Digital Sky Survey and the Low-Frequency Array Two-metre Sky Survey, we investigate the origin and underlying physics of the Baldwin effect of MgII broad emission lines in both radio-…

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astro-ph.SR

Unveiling the period-bounce population of cataclysmic variables: Spectroscopic and time-domain follow-up of eROSITA-selected candidates

S. Hernández-Díaz, B. Stelzer, A. Schwope, D. Muñoz-Giraldo, M. R. Schreiber, J. Brink, K. G. Pradeep, B. T. Gänsicke et al.

During their secular evolution, cataclysmic variable stars (CVs) evolve toward shorter orbital periods ($P_{\rm orb}$) until reaching a minimum near $P_{\rm orb}\sim80$ min, after which they evolve back toward longer periods. CVs that have evolved past this evolutionary turning point are known as period-bouncers (PBs). Despite predictions that 40-80% of all CVs should be PBs, only 3-25% of the observed CV population is composed of PBs, a discrepancy likely due to their intrinsic low luminosities…

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astro-ph.SR

The X-ray catalogue of FGK stars within 10 pc: The coronal temperature-brightness relation explained with the RTV scaling law

M. M. Bennedik, B. Stelzer, M. Caramazza, S. Orlando, A. Binks, J. Robrade

A comprehensive measurement of stellar X-ray emission has important implications for our understanding of stellar dynamos, exoplanet atmosphere loss, and evaporation of protoplanetary disks. We present a catalogue of X-ray detections of the FGK-type main-sequence stars within 10 pc, which accounts for stellar multiplicity and optical loading of the detectors. To build the X-ray catalogue, we analysed all observations from SRG (Spectrum Roentgen Gamma)/eROSITA and XMM-Newton for stars in the FGK…

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astro-ph.SRastro-ph.GA

The Volans-Carina association An X-ray Bridge Between Younger and Older Stellar Populations

Daniela Muñoz-Giraldo, Beate Stelzer, Alex Binks, Enza Magaudda, Stefanie Raetz, Christian Schneider

Nearby young moving groups (NYMGs) provide benchmarks for studying the evolution of magnetic activity and planetary environments at early ages. The Volans-Carina association (VCA), as a pre-main sequence association at a distance of ~90 pc, occupies a sparsely sampled region of parameter space between younger nearby associations and older distant open clusters. We have re-evaluated the membership probabilities of the VCA catalog presented in Gagne et al. (2018a) with BANYAN as well as updated ki…

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astro-ph.HE

Tidal Disruption Events with the SKA

T. An, A. J. Goodwin, J. C. A. Miller-Jones, M. Pérez-Torres, L. Rhodes, X. Shu

Tidal disruption events (TDEs) and related nuclear transients probe jet launching, disk formation and circularization, particle acceleration, and the circumnuclear medium (CNM). However, the small fraction of events launching relativistic jets, the weak or delayed radio emission of many thermal TDEs, and the black-hole demographics of galactic nuclei remain poorly understood. SKA, with microJy sensitivity, wide bandwidth, long baselines, rapid response, and commensal surveys across 50-350 MHz (S…

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astro-ph.HEastro-ph.CO

Thermal or Non-thermal? Diffuse emission in the infall region of stacked galaxy groups

E. Bulbul, X. Zhang, Z. Ding, T. Mistele, M. Kluge, E. Artis, Y. E. Bahar, K. Dennerl et al.

The faint infall regions surrounding the virial radius of galaxy groups remain largely unexplored due to their low X-ray surface brightness. Using the large statistical power of SRG/eROSITA survey observations, we present the first spectroscopic measurement of the intragroup medium (IGrM) in the infall regions of a large sample of low-mass galaxy groups ($M_{\rm tot}<1\times10^{14}\,M_{sun}$), extending to $\sim2\,R_{200m}$ (2.2 Mpc). Through spectral stacking of 827 nearby groups from the first…

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astro-ph.HE

The SRG/eROSITA All-Sky Survey DR2: Cumulative X-ray catalogues from the first three surveys and multi-wavelength counterparts in the western Galactic hemisphere

M. E. Ramos-Ceja, G. Lamer, M. Salvato, A. Merloni, J. S. Sanders, A. Georgakakis, T. Liu, E. Bulbul et al.

The eROSITA telescope array on board the Spektrum-Roentgen-Gamma (SRG) mission began its all-sky survey program in December 2019, scanning the sky at an approximately six-month cadence. Here, we present new catalogues of point-like and extended X-ray sources derived from the first three completed eROSITA all-sky surveys (eRASS:3), covering the western Galactic hemisphere, which Germany's eROSITA consortium holds proprietary rights for. We describe the observational strategy, data processing, and…

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astro-ph.EPastro-ph.SR

Accretion Burst Crystallizes Silicates in a Planet-Forming Disk

Jeong-Eun Lee, Chul-Hwan Kim, Jaeyeong Kim, Seokho Lee, Young-Jun Kim, Seonjae Lee, Giseon Baek, Joel D. Green et al.

Crystalline silicates form at high temperatures (> 900 K; Fabian et al. 2000; Hallenbeck et al. 1998). Their presence in comets (Hanner et al. 1994; Hayward et al. 2000; Wooden et al. 2002; Shinnaka et al. 2018) suggests that high-temperature dust processing occurred in the early Solar System and was subsequently transported outward to comet-forming regions. However, direct evidence for this crystallization and redistribution in Sun-like protostars has remained elusive. By comparing James Webb S…

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astro-ph.EPastro-ph.IM

The International Lunar Reference System

Agnès Fienga

As the exploration of the Moon accelerates in the coming years, there is already an urgent need to standardise the Position, Navigation and Timing of spacecraft, and consequently for the definition of the lunar reference system and frame. This document gathers the most recent recommendations of the the International Association of Geodesy (IAG) / International Astronomical Union (IAU) Joint Working Group (WG) 1.1.3 "Lunar Reference frames" on the topic. Despite the challenges for producing a Lun…

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astro-ph.SR

Long-term high-resolution spectroscopic monitoring of the evolved metal-poor binary PS Gem

V. G. Klochkova, V. E. Panchuk, J. K. Zhao, Y. Q. Wu, N. S. Tavolzhanskaya, G. Zhao

We present results of long-term high-resolution spectroscopic monitoring of the extremely low-metallicity star PS Gem (=HD 52961), associated with IRAS 07008+1050. The spectra were obtained with the 6-meter BTA telescope at a resolving power of R=60000 during 1997--2025, providing a homogeneous dataset spanning nearly three decades. Quantitative measurements of the H$α$ two-peaked profile reveal repeatable phase-dependent variations of the peak-intensity ratio $I_{\rm V}/I_{\rm R}$ and the absor…

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astro-ph.HEastro-ph.GA

Comprehensive X-ray Study of Giant Radio Galaxies with XMM-Newton and Chandra

Niraj Maurya, Satish S. Sonkamble, Suraj Dhiwar, M. B. Pandge, S. Ilani Loubser, Avinash Kale

We present a systematic X-ray spectral analysis of 27 giant radio galaxies (GRGs) using archival \textit{XMM-Newton} and \textit{Chandra} data. Roughly 44\% of the sample show intrinsic absorption ($N_{\mathrm{H,int}} \gtrsim 10^{21}\,\mathrm{cm}^{-2}$), while several exhibit narrow Fe K$α$ emission lines with equivalent widths up to $\sim$570 eV. Soft X-ray features are also common, including thermal plasma emission (kT$\sim 0.2$--0.8 keV) and ionized absorbers, in some cases consistent with hi…

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astro-ph.IM

PhySR: Physics-Informed Neural Network for Super-Resolution Reconstruction in Radio Synthesis Imaging

Hongkun Yang, Li Zhang, Ming Zhang, Yong-Feng Huang

Radio telescope arrays are constrained by the number of antennas and baseline distribution, resulting in incomplete spatial-frequency sampling, limited image resolution, and blurring, distortion, and loss of small-scale structures caused by coupling between the primary and synthesized beams. Existing general-purpose model-driven methods remove observational effects sequentially and may accumulate errors, but cannot directly address limited imaging resolution, while data-driven methods lack expli…

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astro-ph.HE

eRASSU J043115.8-711730: The first pulsating symbiotic super-soft X-ray source in the Magellanic Bridge

Tathagata Saha, Chandreyee Maitra, Philip Charles, Frank Haberl, David Kaltenbrunner, Andrej Udalski, David Buckley, Itumenleng Monageng et al.

The Magellanic Bridge stellar population is a relic of the tidal interaction between the Large and Small Magellanic Clouds. A comprehensive view of the evolution of the Bridge stellar population requires probing the compact remnants of stellar evolution, otherwise hidden at optical wavelengths. The all-sky survey conducted by the eROSITA instrument on-board the Spectrum Roentgen Gamma observatory has discovered a significant population of compact-object-powered systems in the Bridge using X-ray.…

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astro-ph.HE

Distinct Jet Properties in the X-Ray-Obscured State of GRS 1915+105

Xi Yan, Lang Cui, Sergei Trushkin, Shuangjing Xu, Wu Jiang, Zhen Yan, Sándor Frey, Timur Mufakharov et al.

GRS 1915+105 has remained in an X-ray-obscured state since its transition from a long-lasting unobscured state in 2019. We report on 6.7-GHz East Asia VLBI Network observations of GRS 1915+105 obtained during strong radio flares detected at 2.3--11.2 GHz with the RATAN-600 radio telescope in 2025. Our images reveal two contrasting jet morphologies. The first epoch, associated with a flare evolving from an optically thick to an optically thin spectrum, shows a bright radio core accompanied by an…

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astro-ph.GA

The X-ray-Weak Tail of the Quasar Population: Physical Properties and Redshift Evolution of Variability-Selected AGN in eFEDS

P. Arévalo, J. Buchner, M. Salvato, P. Sánchez-Sáez, F. Bauer, M. L. Martínez-Aldama, D. Tubín-Arenas, J. Cerón-Meneses et al.

(abridged) Aims: To characterize variability-selected AGN candidates within the eROSITA Final Equatorial-Depth Survey (eFEDS), leveraging the synergy between optical variability and deep X-ray observations by SRG (Spectrum Roentgen Gamma)/eROSITA, to compare the physical properties of AGN populations selected through complementary methods. Methods: We used a sample of AGN candidates selected via optical variability by Arévalo et al. and cross-match it to the X-ray selected eFEDS AGN sample. Spec…

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astro-ph.IM

Proof of Concept Measurements of Laterally Graded Multilayers for Soft X-ray Spectropolarimetry

Sarah Heine, Herman L. Marshall, Alan Garner, Eric Gulllikson, Nithya Kothnur

This work describes proof of concept measurements for a soft X-ray spectropolarimeter that utilizes laterally graded multilayer mirrors within a grating spectrometer. The work tests two multilayers: a Chromium-Scandium multilayer designed to be utilized at Brewster's angle in the 200-400 eV range and a Tungsten Boron Carbide mirror designed to reflect X-rays at 30 degrees incidence in the 500-850 eV range. We present measurements of monochromatic, polarized light reflecting off of these multilay…

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astro-ph.GA

Galactic HII regions in LAMOST Medium-Resolution Spectroscopic Survey of Nebulae

Yunning Zhao, Wei Zhang, Lin Ma, Shiming Wen, Tao Jing, Cheng Li, Zheng Zheng, Aiyuan Yang et al.

Based on LAMOST Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N) data and WISE Galactic HII region catalog, we construct a sample of 280 Galactic HII regions and candidates in the Outer Galaxy (80$^{\circ}$ $\lesssim$ l $\lesssim$ 220$^{\circ}$). Using MRS-N optical spectra, we measure four emission lines (H$α$, [NII]$λ$6584, [SII]$λλ$6717,6731) and use line-ratios to spectroscopically confirm 255 HII regions, including 90 previously "Known" HII regions and 165 newly classified ones. We…

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astro-ph.HE

On the Blueprint of Active Galaxies Producing Neutrinos

Chen Li, Francis Halzen

Based on the observation of the active galaxies NGC 1068 and TXS 0506+056, and on additional evidence for the sources NGC 4151, CGCG 420-015, NGC 7469, and the Circinus Galaxy emerging from IceCube data, we make the case for the production of high-energy neutrinos within a few gravitational radii of supermassive black holes surrounded by a dense plasma radiating X-rays. X-rays represents the target for the production of neutrinos by protons accelerated near the black hole; they also absorb the g…

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astro-ph.HE

An extra hard spectral component peaking at sub-GeV in the prompt emission of GRB 260226A

Yi-Yun Huang, Hai-Ming Zhang, Ruo-Yu Liu, Xiang-Yu Wang

The prompt emission spectra of gamma-ray bursts (GRBs) have long been empirically described by the Band function over the keV--MeV range, whereas several \textit{Fermi}/LAT-detected GRBs show evidence for an extra hard component at higher energies. Here we present a joint GBM--LAT study of GRB~260226A, a rare LAT seeded onboard trigger GRB, and find that an extra sub-GeV component is present. In the time-resolved analysis, we find that a cutoff power-law model fits the spectral data of the extra…

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astro-ph.IM

Design and testing progress towards the first flight of the rocket experiment demonstration of a Soft X-ray Polarimeter (REDSoX)

Sarah N. T. Heine, Herman L. Marshall, Alan Garner, F. Elio Angile, C. Marc Baker, Stephen Bongiorno, Leonardo Drake, H. Moritz Gunther et al.

The Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX) is a NASA-funded, sounding rocket mission. The rocket payload will measure polarization strength and direction as a function of energy in the 0.2-0.4 keV band, providing complementary measurements to those made by IXPE in the 2-8 keV band. The first flight, scheduled for 2028, will provide a technology demonstration of our polarimeter concept, which utilizes an aligned system of a focusing optic, Critical-Angle Transmission…

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astro-ph.HE

Depolarization Induced by Rapid Polarization Angle Swings: A Common Feature of Pulsars and Fast Radio Bursts?

Yu-Chen Huang, Jie-Shuang Wang, Song-Bo Zhang, Zi-Gao Dai

The polarization angle (PA) of pulsars and fast radio bursts (FRBs) provides a useful diagnostic of the magnetic fields in their emission regions and is therefore crucial for understanding their radiation and origins. Within a general geometric framework for polarized emission from a rotating neutron star, we suggest a possible anti-correlation between the degree of linear polarization $Π_\text{L}$ and $d\text{PA}/dt$, the time derivative of the PA, as a common feature of pulsars and FRBs. The d…

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astro-ph.EP

Rotation and Mutual Eclipse Events Season in the Kuiper Belt: (524366) 2001 XR$_{254}$

Audrey Thirouin, William M. Grundy, Scott S. Sheppard, Keith S. Noll, José María Gómez-Limón, Benjamin Proudfoot

(524366) 2001 XR$_{254}$ is a dynamically Cold Classical Kuiper Belt Object that is a nearly equal-sized wide binary whose upcoming mutual events season makes it a particularly valuable target for physical characterization. In advance of the mutual eclipse events, we conducted a ground-based photometric observing campaign between 2021 and 2026 using the \textit{Lowell Discovery Telescope} to investigate the rotational and physical properties of the system, to refine predictions for its future mu…

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