研究動向

astro-ph.SR2026年7月20日

A universal scaling between damping time and period of quasi-periodic pulsations from solar EUV brightenings to X-ray stellar flares

Daye Lim, Tom Van Doorsselaere, Valery M. Nakariakov, S. Krishna Prasad, David Berghmans, Laura A. Hayes, Kyung-Suk Cho, Sujin Kim et al.

Recent high spatial and temporal resolution extreme-ultraviolet (EUV) imaging observations have revealed that quasi-periodic pulsations (QPPs), a ubiquitous signature of impulsive energy release in solar and stellar flares, are also present in much smaller-scale coronal events known as EUV brightenings. Whether QPPs observed across such disparate spatial and energetic scales share a common physical origin remains an open question. Here we analyse 2,146 EUV brightenings observed with Solar Orbite…

詳細を見る →

astro-ph.SRastro-ph.IM2026年7月20日

SpecFANN: Spectral Fitting via Artificial Neural Networks I. A deep learning based fastwind emulator and fitting suite

M. Abdul-Masih, C. Hawcroft, T. Lechien, S. Simon-Diaz, H. Sana, K. Deshmukh, J. Vrancken, J. I. Villaseñor et al.

The importance of massive stars cannot be overstated: they are powerful probes of the early universe, play a vital role in the chemical and mechanical evolution of their host environments and their end products allow us to study the most extreme physics in the universe. Obtaining accurate stellar and surface parameters for large samples of massive stars is vital to our understanding of how they evolve, and how their births, lives and deaths affect their surroundings. With the large volume of dat…

詳細を見る →

astro-ph.COastro-ph.HE2026年7月20日

Constraints on Primordial Black Hole Dressed by Dark Matter Halo from Microlensing Effect of Fast Radio Bursts

Hong-Rui Tao, Huan Zhou, Cheng-Gang Shao, Xiao-Long Gong, Zheng-Xiang Li

Primordial black holes (PBHs) are not only considered as a candidate for dark matter, but also as potential sources of gravitational waves from binary black hole mergers by the LIGO-Virgo-KAGRA and as seeds for the supermassive black holes observed by the James-Webb Space Telescope, thereby remaining intense interest in cosmology and astrophysics. Fast radio bursts (FRBs) are bright millisecond-duration radio transients whose physical origin remains elusive, which have rapidly developed into one…

詳細を見る →

astro-ph.COastro-ph.HE2026年7月20日

Constraints on Primordial Black Hole Dressed by Dark Matter Halo from Microlensing Effect of Fast Radio Bursts

Hong-Rui Tao, Huan Zhou, Cheng-Gang Shao, Xiao-Long Gong, Zheng-Xiang Li

Primordial black holes (PBHs) are not only considered as a candidate for dark matter, but also as potential sources of gravitational waves from binary black hole mergers by the LIGO-Virgo-KAGRA and as seeds for the supermassive black holes observed by the James-Webb Space Telescope, thereby remaining intense interest in cosmology and astrophysics. Fast radio bursts (FRBs) are bright millisecond-duration radio transients whose physical origin remains elusive, which have rapidly developed into one…

詳細を見る →

astro-ph.IMastro-ph.HE2026年7月20日

Calibration database design for the wide-field X-ray telescope on board the Einstein Probe

Huaqing Cheng, Hai-Wu Pan, Yuan Liu, Donghua Zhao, Wenxin Wang, He-Yang Liu, Chen Zhang, Zhixing Ling et al.

The wide-field X-ray telescope (WXT) is the primary payload of the Einstein Probe (EP) mission. Utilizing innovative lobster-eye micro-pore optics (MPO), it achieves an unprecedented combination of a large instantaneous field-of-view (FoV) and high detection sensitivity. Precise scientific data analysis relies fundamentally on a standardized and robust calibration database (CALDB). In this paper, we present the design and implementation of the WXT CALDB. The database is designed to manage calibr…

詳細を見る →

astro-ph.IMastro-ph.HE2026年7月20日

Onboard catalog of known X-ray sources for EP-WXT

He-Yang Liu, Haiwu Pan, Yuan Liu, Hong-Bo Cai, Yuyin Tan, Haitao Xu, Changbin Xue, Xiaojin Sun et al.

The Einstein Probe (EP) is dedicated to explore the dynamic X-ray universe and capture transient events in real time with its Wide-field X-ray Telescope (WXT). However, WXT's unprecedentedly large instantaneous field of view, exceeding 3,600 square degrees, simultaneously encompasses numerous known X-ray emitters. Distinguishing genuine novel transients from these persistent sources is a critical observational challenge. To resolve this, EP-WXT incorporates a dedicated reference catalog of known…

詳細を見る →

astro-ph.GAastro-ph.SR2026年7月20日

The initial conditions and initial mass functions of Alpha Persei, Pleiades and Praesepe

L. Hobart, H. Baumgardt, S. Sweet

We have determined the initial mass function (IMF) and structural properties of the open clusters Alpha Persei, Pleiades and Praesepe using Gaia DR3 astrometry and photometry. Cluster members were identified using primarily Gaia astrometry, supplemented with near-infrared UKIDSS and optical HIPPARCOS survey data with stellar masses down to $0.10-0.17$ MSun. We measure and correct for unresolved binaries in each cluster using photometry and Monte Carlo simulations in a Bayesian framework, finding…

詳細を見る →

astro-ph.GA2026年7月19日

Ongoing Morphological Transformation from Elliptical to Spiral Galaxies Induced by Gas Accretion from Neighboring Galaxies

Gene Yun, Sang Hyeok Im, Ho Seong Hwang, Changbom Park, Hyeonguk Bahk

We present results from spectroscopic observations of three interacting galaxy systems, each associated with a primary galaxy - VCC 1748, SDSS J1106, and 2MASX J0834 - which have been proposed as potential examples of reverse morphological transformation from elliptical to spiral types driven by external gas accretion. Using Gemini/GMOS longslit spectroscopy, we obtain spectra along longslits connecting the regions of interest between the two galaxies in each pair. We model the spatially binned…

詳細を見る →

astro-ph.GAastro-ph.SR2026年7月19日

Super-Jeans Fragmentation and Supply-Limited Accretion: Environment-Dependent Co-Evolution of Low- and High-Mass Cores

Dan Miao, Guang-Xing Li, Patricio Sanhueza

Protostellar core formation and growth in high-mass star-forming regions remain key to understanding massive star birth. We analyze the masses of 839 cores (resolved at scales of a few thousand au) from the ASHES project targeting 39 massive infrared dark cloud clumps. The masses of the three most massive cores scale linearly with the total core mass. They maintain a constant mass fraction of ~25%, 16%, and 10% along the mass growth sequence. These fractions reveal that the progenitor seeds dest…

詳細を見る →

gr-qcastro-ph.HE2026年7月19日

Probing Nonlinear Logarithmic Kalb-Ramond Black Holes: Particle Dynamics, Epicyclic Oscillations and Thermodynamic Signatures

Aftab Ansari, Rajesh Kumar, Praveen Kumar Dhankar

In contrast to conventional linear coupling frameworks, the proposed work investigated the nonlinear effects that become more significant in the strong field regime of a black hole. We have investigated a new class of Kalb Ramond black holes generated by a nonlinear logarithmic coupling of the field, referred to as a Logarithmic Kalb Ramond black hole. The logarithmic coupling introduces strong-field modifications to the spacetime geometry, leading to significant departures from the Schwarzschil…

詳細を見る →

astro-ph.SRastro-ph.GA2026年7月19日

Magnetic fields in Massive Star-Forming Regions (MagMaR). VIII. Magnetic field overrun by gravity in GGD 27's accretion streamers

M. Fernández-López, J. A. López-Vázquez, J. M. Girart, P. Sanhueza, L. A. Zapata, P. C. Cortés, H. Beuther, G. Busquet et al.

Context. Accretion streamers connected to protostellar disks and/or envelopes are thought to transport material across several thousand of au. Whether the motions of the gas comprising these streamers are dominated by gravity, large scale external turbulence or the action of magnetic fields is still under scrutiny. Aims. The aim of this work is to understand the role of the magnetic fields in the star-formation processes, in particular the role that magnetic forces have in potentially leading fl…

詳細を見る →

astro-ph.GA2026年7月19日

Disentangling the Morphology of Palomar~5: Effects of the Bar, Spiral Arms, LMC, and Halo Flattening

Zhenghao He, Long Wang, Zi-yi Zhou, Yang Huang, Eugene Vasiliev

The Palomar~5 (Pal~5) globular cluster and its tidal tails provide a sensitive probe of globular-cluster evolution in the time-dependent Milky Way potential. We study the past 3~Gyr evolution of Pal~5 using collisional direct \(N\)-body simulations with \texttt{PeTar}, adopting Galactic potential models that include spiral arms, the Galactic bar, halo flattening, the Large Magellanic Cloud (LMC), and bar deceleration. We find that halo shape strongly influences the projected stream track, reflec…

詳細を見る →

nucl-thastro-ph.HEastro-ph.SRhep-th2026年7月19日

The equation of state for neutron stars

Veronica Dexheimer

This chapter is intended as an introduction to dense matter and the equation of state of neutron stars and their mergers. It begins with a brief description of neutron star interiors, followed by a historical overview of the theoretical frameworks used to describe them focusing on relativistic formalisms, including different degrees of freedom, models, symmetries, and phases. It also provides an overview of our current understanding of dense matter (including theory, experiments, and observation…

詳細を見る →

astro-ph.SR2026年7月19日

Constraining the radial decay timescale of solar surface magnetic field through a comparative study of data-assimilative 2D surface flux transport and 3D dynamo models

Soumyadeep Chatterjee, Gopal Hazra

The polar magnetic field is the most reliable precursor for predicting the amplitude of the solar cycle, and the 2D surface flux transport (SFT) model is widely used to reconstruct its evolution. Traditional 2D SFT models can not capture the surface-interior coupling of the surface field, causing delays in polar field reversals. This deficiency is conventionally corrected by adding a decay term $-B_r/τ$ with a poorly constrained radial decay timescale $τ$. Here, we present a self-consistent esti…

詳細を見る →

astro-ph.IMastro-ph.SR2026年7月19日

Continuous Ultra-Low-Frequency Solar Radio Monitoring with ALBATROS from the High Arctic

Aman Chokshi, Mohan Agrawal, Christopher Barbarie, Joëlle-Marie Bégin, Benjamin Cheung, Hsin Cynthia Chiang, Cherie K. Day, Eamon Egan et al.

In the Canadian High Arctic, nearly five months of continuous daylight enable uninterrupted low-frequency solar monitoring. We present the first solar science results from the Array of Long Baseline Antennas for Taking Radio Observations from Seventy-Ninth Parallel (ALBATROS). This broadband radio array is designed to explore the largely uncharted radio sky below 30 MHz, where polar ionospheric conditions permit access to frequencies rarely accessible from ground-based sites. Using observations…

詳細を見る →

astro-ph.GAgr-qc2026年7月19日

Temporal Correlations Between Fuzzy Dark Matter and Baryonic Matter in Virialized Core-Halo Structures

Ivan Alvarez-Rios, Francisco S. Guzman

Fuzzy Dark Matter (FDM) predicts the existence of virialized halos with interference-driven granular structure generated by the wave nature of ultralight bosons. Since these fluctuations produce time-dependent gravitational fields, they can be proposed as a potential source of observable dynamical effects on baryonic matter. In this work we test whether such fluctuations generate measurable temporal correlations between FDM and a coupled gas component. We evolve coupled FDM-gas configurations wi…

詳細を見る →

astro-ph.HEgr-qc2026年7月19日

Electromagnetic Emission from a Black Hole Evaporating in External Magnetic Field

Soumya Samrat Mandal, Maxim Lyutikov

We describe a classical (non-quantum) radiation process: additional (to Hawking) emission by a black hole evaporating in an external magnetic field in vacuum. The electromagnetic radiation process is completely electric charge-free and bears some resemblance to the Gertsenshtein-Zel'dovich effect. The time evolution of the spacetime metric perturbs a static background magnetic field, inducing a radiative field that acts as an effective electromagnetic source even in the absence of physical charg…

詳細を見る →

astro-ph.SRastro-ph.GA2026年7月18日

Escaped White Dwarf Candidates from Open Clusters

Huahui Yan, David R. Miller, Jingkun Zhao, Jincheng Guo, Chengyuan Li

Observations reveal a pronounced deficit of white dwarfs (WDs) in open clusters (OCs) relative to theoretical expectations, suggesting that a significant fraction of WDs may have escaped from their parent clusters after formation. In this work, we perform a systematic search for escaped WD candidates from OCs by back-tracing the motions of WDs and star clusters from Gaia DR3 catalogs. We identify 476 candidate WDs with kinematics consistent with having escaped from one of 175 OCs. A control-fiel…

詳細を見る →

astro-ph.GAastro-ph.SR2026年7月18日

Machine learning prediction of binary formation in three-body gravitational encounters

Ahmad Farhani Asl

Three-body encounters are frequent events in stellar systems, intrinsically chaotic, and computationally costly to model with direct N-body integration. Predicting whether such encounters lead to binary formation is therefore challenging, particularly in large-scale simulations. We aim to develop an accurate and physically interpretable machine-learning model that predicts binary formation from the initial conditions of three-body encounters, to assess its reliability, and to identify the physic…

詳細を見る →

astro-ph.SRastro-ph.GA2026年7月18日

Determination of [Fe/H] in Fundamental mode Classical Cepheids from Gaia DR3 light curve Fourier parameters

Roberto Molinaro, Vincenzo Ripepi, Marcella Marconi, Massimiliano Gatto, Erasmo Trentin, Mami Deka, Giulia De Somma, Ilaria Musella et al.

Estimating the iron abundance ([Fe/H]) of Classical Cepheids (CCs) is crucial both for validating the cosmic distance scale through the Period-Luminosity relation and for tracing the chemical evolution of young stellar populations. However, standard spectroscopic determinations are highly time-consuming, limiting their application to large or distant samples. This work delivers a practical, multi-band alternative by investigating whether light-curve Fourier parameters derived from Gaia mission p…

詳細を見る →

astro-ph.GAastro-ph.SR2026年7月18日

Predicting the unpredictable: binary--single scattering with machine learning

Ahmad Farhani Asl, David Fonseca Mota, Dennis Fremstad, Fatemeh Rahimi

Binary--single encounters occur frequently in stellar systems, constitute a non-integrable chaotic three-body problem, and are computationally expensive when treated with N-body codes. We aim to construct an accurate and physically interpretable surrogate model for binary--single scattering final states (ionization, flyby, exchange, or hierarchical), evaluate the reliability of its probabilistic predictions, and trace its predictive failures to the underlying chaotic nature of the scattering pro…

詳細を見る →

astro-ph.HE2026年7月18日

Fermi-LAT Detection of a Gamma-ray Excess toward the Radio-quiet Narrow-line Seyfert 1 Galaxy 1H 1934-063

Yangji Li, Jinming Bai, Xiong Jiang, Kaixing Lu

We report a $γ$-ray excess toward the radio-quiet narrow-line Seyfert 1 galaxy 1H 1934-063 using data collected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope and taking into account the LAT 16-year Source List (FL16Y). During the flare interval, the excess is detected in the 1--500 GeV band at a significance of $\sim 5.2σ$ (TS = 27.12), with a photon flux of $(4.94\pm2.33)\times10^{-10}$ ph cm$^{-2}$ s$^{-1}$ and a hard photon index of $Γ=1.50\pm0.25$. The best-f…

詳細を見る →

astro-ph.GAastro-ph.SR2026年7月18日

Molecule-dependent Abundance Behavior of Oxygen-bearing Complex Organics in High-Mass Star-Forming Regions: A Uniform 50-source Survey

Xuefang Xu, Mingwei He, Qian Gou, Jiao He, Junzhi Wang, Donghui Quan, Di Li, Laurent Pagani et al.

We present a uniform IRAM-30\,m survey analysis of four oxygen-bearing complex organic molecules (COMs), methanol (CH$_3$OH), acetaldehyde (CH$_3$CHO), methyl formate (CH$_3$OCHO), and dimethyl ether (CH$_3$OCH$_3$), toward 50 high-mass star-forming regions (HMSFRs) associated with 6.7\,GHz methanol masers. Column densities were derived through a homogeneous rotation-diagram approach, with CH$_3$CN used as a proxy excitation-temperature reference when needed. In CH$_3$OH-normalized abundance-rat…

詳細を見る →

astro-ph.EPastro-ph.IM2026年7月18日

Resolving core-envelope degeneracies in giant planets and sub-Neptunes: constraining the equivalence in the presence of dilute gradients

Christian Wilkinson, Benjamin Charnay, Stéphane Mazevet, Baptiste Perrier, Anne-Marie Lagrange, Lukas Delay

The widespread recognition of dilute, "fuzzy" cores in giant planets and massive volatile mantles in sub-Neptunes has made interior modelling a highly degenerate, multi-dimensional problem. To map these degeneracies, we present fuzzycore, an open-source static structural integrator with a unified layered architecture spanning rock-water-envelope sub-Neptunes through volatile-rich gas giants. The framework supports dense parameter sweeps over compositional gradients at fixed observed $(M_p, R_p,…

詳細を見る →

astro-ph.GA2026年7月18日

Asymmetries in spatially unresolved 21-cm emission line profiles of isolated galaxies

Aditya Manuwal, H. M. Hernández-Toledo, J. A. Vázquez-Mata, Diana Serrato Barrajas, Aldo Rodríguez-Puebla, Vladimir Ávila-Reese, A. R. Calette

The origin of asymmetry in the ${\rm H}\,{\scriptsize{\rm I}}$ of galaxies remains an elusive problem, largely due to the difficulties associated with distinguishing between its secular and external contributors. We have compiled a sample of local isolated galaxies from the UNAM-KIAS and the latest AMIGA samples with near-complete beam coverage and robust estimates of ${\rm H}\,{\scriptsize{\rm I}}$ line asymmetry. The ${\rm H}\,{\scriptsize{\rm I}}$ measurements are based on single-dish spectra…

詳細を見る →

astro-ph.EP2026年7月18日

Distribution of Chemically-Processed Dust in a Viscously Evolving Protoplanetary Disk: Application to Crystalline Silicates in Comets

Lily Ishizaki, Shogo Tachibana, Shigeru Ida

Dust particles undergo chemical reactions in protoplanetary disks according to their environments, producing compositional diversity in planetary materials. Extraterrestrial records of irreversible reactions, such as crystallization of amorphous silicates, provide particularly strong constraints on the early evolution of the protosolar disk. In this study, we investigate such irreversible reactions and the spatiotemporal distribution of reacted dust in a viscously evolving disk using Monte Carlo…

詳細を見る →

astro-ph.GA2026年7月18日

Tidal Structures Around Edge-On Galaxies in Deep Imaging Surveys

Kyle R. Adams, Aleksandr Mosenkov, Jonah Seguine, Lydia Stacey, Thea Spigarelli, Jonah George

We present a statistical study of low-surface-brightness (LSB) tidal structures in two large samples of edge-on disk galaxies. Our primary sample comprises 5606 galaxies from the Edge-on Galaxies In SDSS (EGIS) catalog, analyzed using imaging from the DESI Legacy Imaging Surveys, supplemented by Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) data and deep Apache Point Observatory (APO) follow-up observations for selected objects. To assess the robustness of our results, we also examine an…

詳細を見る →

astro-ph.SR2026年7月18日

Effective temperatures estimation of low-mass stars and identification of T Tauri stars in LAMOST DR10 using machine learning

C. D. Millan-Valderrama, J. Hernandez, B. Sabogal, J. Muñoz

We present effective temperature (Teff) estimates of low-mass stars and T Tauri stars (TTS) candidate detections derived from automated spectroscopic measurements and low-complexity machine-learning models applied to the LAMOST DR10 V2 survey. Equivalent widths of key diagnostic spectral features, including the atomic lines Halpha, LiI 6708 AA and TiO/VO molecular bands, are automatically measured for all stars within 1 kpc observed by LAMOST. Using nine spectral features as inputs, we train a G…

詳細を見る →

astro-ph.HEastro-ph.IMgr-qc2026年7月18日

A Four-Dimensional Gaussian Random Field Generator for Modeling Spatiotemporal Variability in Astrophysical Sources

Alejandro Cárdenas-Avendaño, Diego Rubiera-Garcia, Frederic H. Vincent

Semi-analytic models of black-hole movies require both an emitting flow prescription and a time-dependent source variability. Existing prescriptions are often limited to either equatorial emission or time-independent sources. In this work we present a unified model for these two ingredients. First, we prescribe an off-equatorial, nongeodesic Kerr fluid rotation law by lifting an equatorial specific-angular-momentum profile to cylindrical surfaces, setting the polar component of the four-velocity…

詳細を見る →

astro-ph.EP2026年7月18日

Planet-wide, Concentric Density Waves in Venus's Upper Atmosphere Revealed through Polarimetry?

Gourav Mahapatra, Michiel Rodenhuis, Frans Snik, Daphne M. Stam, Loïc Rossi, Christoph Keller

We report observations of faint ($10^{-6}$), concentric, planet-wide rings in the polarized flux of sunlight that is reflected by Venus, obtained during a serendipitous, 36-minute run in 2010, with the highly sensitive Extreme Polarimeter (ExPo) on the William Herschel Telescope. The rings appear to be centered slightly downwind of the sub-solar point, are visible in different filters across the visible, and are not obvious in the simultaneous total flux observations. ExPo's dual-beam exchange a…

詳細を見る →