研究動向

astro-ph.GA2026年7月24日

The disrupted chemical enrichment history of the Milky Way driven by gas accretion

Jianhui Lian, Qinhao Shao, Min Du, Hanyuan Zhang, Xinxin Duan, Xin Wang, Zheng Zheng

As the only galaxy enabling temporally-resolved observations from an internal vantage point, the Milky Way as a galaxy offers unique insights into galactic chemical enrichment history, establishment of fundamental scaling relations, and the underlying astrophysical processes. However, this insider perspective also introduces strong selection effects, hindering direct measurement of the Milky Way's global properties and comparison with the broader galaxy population, for the vast majority of which…

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astro-ph.GA2026年7月24日

Long Tidal Tails of NGC 5024 Hidden in LMS-1 and NGC 5053 Tidal Streams

Xianhao Ye, Yong Yang, Jingkun Zhao, Hao Tian, Yuqin Chen, Gang Zhao

We report the discovery of long tidal tails associated with the globular cluster (GC) NGC 5024. A modified matched filter applied to Gaia DR3 data reveals a broad stellar stream spanning $α\approx 230^{\circ}-175^{\circ}$. The stellar stream overlaps on the sky with the LMS-1 and with the simulated stream of the GC NGC 5053, and all three share similar proper motions and metallicity. Our member candidates may therefore be a mixture of stars from NGC 5024, NGC 5053, and LMS-1. Nevertheless, the t…

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gr-qcastro-ph.HE2026年7月24日

From the Early Slope to Curvature: Future Prospects and challenges for Astrophysical Parameter Estimation Using the Core-Collapse Supernova High-Frequency Feature

Alejandro Casallas-Lagos, Marek Szczepańczyk, Michele Zanolin, Anthony Mezzacappa

Gravitational-wave (GW) signals from core-collapse supernovae (CCSNe) contain both stochastic and deterministic components. Among these, the High-Frequency Feature (HFF), associated with PNS oscillations, has emerged as a robust observable for probing dense-matter physics. Previous studies of the HFF have primarily focused on the early-time slope as a diagnostic of PNS contraction and its dependence on the equation of state (EOS). In this work, we extend the analysis beyond the early-time linear…

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gr-qcastro-ph.HEastro-ph.IM2026年7月24日

Classifying the nuclear equation of state in LVK interferometric noise through core-collapse supernova gravitational-wave signatures using convolutional neural networks

Alejandro Casallas-Lagos, Marek J. Szczepańczyk, Michele Zanolin, Anthony Mezzacappa, Javier M. Antelis, Daniel Murphy, Claudia Moreno

This paper presents a convolutional neural network (CNN) approach to classifying the nuclear equation of state (EOS). As illustrative examples, we use five two-dimensional core-collapse supernova (CCSN) simulations that differ only in their EOS. We analyze estimates of the initial slope of the high-frequency feature (HFF) reconstructed in real interferometric data from the O3b LIGO-Virgo-KAGRA (LVK) observing run at Galactic source distances of 1, 5, and 10 kpc. The CNN classifier achieves an ov…

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astro-ph.SRastro-ph.HE2026年7月24日

Spectral evolution of mildly relativistic electrons in solar flares

Gregory D. Fleishman, Tatyana Kaltman, Sijie Yu, Gelu Nita

Solar flares are a powerful engine capable of accelerating ambient plasma particles to high nonthermal energies. A key characteristic of these particles is their energy spectrum. Numerous studies of nonthermal hard X-ray emission established that a typical spectral evolution of the nonthermal electrons with energies of dozens keV follows a soft-hard-soft pattern in impulsive events and soft-hard-harder pattern in some long-duration events. Here we extend the study of the spectral evolution to th…

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astro-ph.GA2026年7月24日

Stacked Reverberation Mapping of High Redshift Quasars in DESI. I. Feasibility Analysis

Rahma Alfarsy, R. E. A. Canning, Eva-Maria Mueller, Jessica Aguilar, Steven Ahlen, David Alexander, Davide Bianchi, David Brooks et al.

The broad line region of quasars has long been probed by reverberation mapping techniques that measure time lags between continuum and broad emission line variations. Stacked reverberation mapping has been proposed as a less observationally expensive alternative to traditional methods. This ensemble approach also reduces biases from small-number statistics. The Dark Energy Spectroscopic Instrument (DESI) is conducting the most extensive spectroscopic survey of quasars to date. We create mock lig…

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astro-ph.HEastro-ph.GA2026年7月24日

A GRMHD-Calibrated Semi-Analytical Model for Hot Sub-Keplerian Accretion Flows in Kerr Spacetime

Nabin Bhushal, Manil Khatiwada, Yogesh Maharjan, David Garofalo, Chandra B. Singh

We develop a simple, semi-analytical, kinematic model for hot, thick accretion flows, constructed by interpolating between Keplerian and free-fall geodesic solutions in the Kerr metric. Unlike self-consistent general relativistic magnetohydrodynamics (GRMHD) frameworks, our model contains no explicit magnetic fields or stress terms; instead, it uses a smooth, radially varying transition function T(r) to connect the velocity components from near-Keplerian rotation at large distances to a free-fal…

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astro-ph.SR2026年7月24日

Magnetically guided accretion and extremely slow rotation in a metal-enriched white dwarf

S. Bagnulo, M. A. Stroet, C. P. Folsom, M. A. Hollands, J. D. Landstreet, G. Ramsay

White dwarfs that show atmospheric metal enrichment offer a direct window into the bulk composition of exoplanetary material and provide some of the most direct constraints on the building blocks of rocky exoplanetary systems. Recent work has suggested that magnetic fields may influence how this material is accreted, potentially channelling debris along field lines and retaining it near magnetic poles rather than allowing it to be redistributed uniformly across the stellar surface. Here we repor…

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astro-ph.SRastro-ph.EPastro-ph.GA2026年7月24日

Rate of caustic crossing microlensing events in stellar binary lenses with significant orbital motion

Arjun Murlidhar, B. Scott Gaudi, Todd. A. Thompson

Binary lens microlensing events in which the source crosses a caustic produce sharp, distinctive magnification peaks and can therefore be readily identified. In this paper, we explore the importance of binary orbital motion for the binary lens caustic crossing cross section. If the orbital timescale of the binary system is smaller than the Einstein ring crossing timescale, the caustics sweep out a larger area in the source plane, generally enhancing the cross section. We find that face-on binari…

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astro-ph.GA2026年7月24日

A Multiwavelength Inventory for the Local Group L-band Survey I: Atlas and Radial Profiles of Local Group Galaxies

Cosima Eibensteiner, Adam K. Leroy, Jiayi Sun, Erik Roslowsky, Eric W. Koch, Nickolas Pingel, Chang-Goo Kim, Laura B. Chomiuk et al.

Resolving atomic gas at $\lesssim100$ pc physical resolution is currently feasible only for the very nearest galaxies. We combine 120 pc resolution HI data using the Karl G. Jansky Very Large Array (VLA) from the first data release of the Local Group L-Band Survey (LGLBS) with uniformly processed infrared, ultraviolet, H$α$, and CO maps. We analyze the radial profiles of gas, stars, and recent star formation for six local galaxies: M31, M33, IC 10, IC 1613, NGC 6822, and WLM. Across the sample,…

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astro-ph.COastro-ph.GAastro-ph.HEgr-qc2026年7月24日

The diffraction-lensing interpretation of GW231123 with astrophysical priors

Mark Ho-Yeuk Cheung, Digvijay Wadekar, Matias Zaldarriaga, Tejaswi Venumadhav, Javier Roulet, Ajit Kumar Mehta

GW231123, if unlensed, is a rare binary black hole merger with high masses and high spins for both progenitors. We show that the signal is better fitted by a lower-mass, lower-spin merger that is diffraction-lensed by an isolated object of redshifted mass $\sim 1000\,\rm M_\odot$, modeled either as a point mass or as a spherically symmetric compact halo. Because diffraction-lensed events are also rare, hypothesis testing should quote the posterior odds ratio rather than the Bayes factor, which r…

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astro-ph.GA2026年7月24日

From relics to stripped systems: the environmental origin of compact galaxies

Guangwen Chen, J. Alfonso L. Aguerri, Carlos del Burgo, Stefano Zarattini

Compact galaxies represent a key population for understanding galaxy evolution, but the relative role of internal structure and environment in shaping their origin remains unclear. We aim to investigate how the abundance and quenching of compact galaxies depend on environment, and to determine whether their formation is governed by a single evolutionary pathway or multiple channels. We analyse a large sample of galaxies in the nearby Universe ($z<0.05$) with stellar masses in the range $8.2<\log…

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astro-ph.GAphysics.atom-ph2026年7月24日

Emissivity line ratios for [Mn III] and spectral diagnostics of H II regions

Zher Samak, Sultana N. Nahar, Anil K. Pradhan

We present the first theoretical emission-line study of Mn III as potential determinant of physical conditions and manganese abundance. We compute atomic data for a set of Mn III lines and line emissivity ratios as temperature-density diagnostics. Accurate relativistic Breit-Pauli R-matrix calculations have been carried out for electron impact excitation of Mn III transitions that have not been previously studied. Selected forbidden lines are shown to be sensitive to temperature and density unde…

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astro-ph.IM2026年7月24日

Determination of Earth's Orbital Parameters Using Doppler Measurements

Gary Atkins, Marcus Leech, Daniel Marlow, Doug Yuill

Precision determinations of the parameters of Earth's orbit around the Sun using methods based on the Doppler shift of 21-cm emissions from the galaxy and the repetition rate of pulsar J0332+5434 are reported. The observed values and statistical errors for the orbital parameters for the 21-cm observations are semi-major axis $a = 1.00020 \pm 0.00015~{\rm au}$ and eccentricity $e= 0.017077 \pm 0.000077$. For the pulsar observations, the observed values are $a = 1.000034 \pm 0.000034~{\rm au}$ and…

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astro-ph.IM2026年7月24日

The FastrSHWFS Development & Test Results

Natasha Popenoe, Benjamin Gerard, Dominic Sanchez

The recent 2020 Decadal Survey of Astronomy and Astrophysics listed habitable exoplanet imaging with future extreme adaptive optics (AO) on 30m-class telescopes as a key priority in the coming decade. However, there is a current 100x contrast gap between the best systems today and what is needed to enable this goal. Astronomical AO is a required approach to enable ground-based diffraction-limited imaging of exoplanets on future extremely large telescopes. Time lag between the end of an exposure…

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astro-ph.GA2026年7月24日

Where Do Quasars Live? DESI DR1 Constraints from PAC Measurements

Shanquan Gui, Kun Xu, Donghai Zhao

Quasar environments connect the growth of supermassive black holes, active galactic nucleus feedback, and galaxy evolution. Small-scale quasar clustering probes the one-halo regime and can test whether quasar activity depends on central--satellite status. We seek to obtain precise small-scale measurements of quasar environments at $0.8<z<1.0$ and use them to constrain the quasar--halo connection, particularly the relative probability for satellite subhalos and central halos of the same halo accr…

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astro-ph.HEastro-ph.COastro-ph.GA2026年7月24日

On the astrophysical origin of cosmic rays: Constraining the Ultra-High-Energy Cosmic Ray Horizon through Nearby Galaxy Distributions

F. Dávila-Kurbán, F. Duplancic, D. Garcia Lambas

The origin of ultra-high-energy cosmic rays (UHECR) remains a central open problem in astroparticle physics. The observed large-scale anisotropy of UHECR arrival directions above several EeV, together with the spectral suppression at the highest energies, suggests extragalactic sources confined to a limited volume of the nearby Universe, though the effective spatial scale of this contribution remains poorly constrained. We aim to constrain the effective propagation horizon of UHECR with energies…

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astro-ph.EPphysics.geo-ph2026年7月24日

Onset of dynamo action in planetesimals

Ludovic Huguet, Jonathan E. Mound, Christopher J. Davies, James F. J. Bryson

Several meteorites have been found to carry primary remanent magnetizations imparted by fields generated within planetesimal cores during the early solar system. Thermal evolution models have shown that thermal convection likely drove the dynamo in the early evolution of these bodies. In such small cores, the magnetic Reynolds number is thought to be close to the threshold for dynamo action. However, the critical value of the magnetic Reynolds number, meaning its value at the onset, is also poor…

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astro-ph.GA2026年7月24日

SED Fitting of the Globular Clusters in Abell 2744 at z=0.3

Jinoo Kim, William E. Harris

We present a spectral energy distribution (SED) fitting analysis of globular cluster (GC) candidates in Abell 2744, a massive galaxy cluster at redshift z = 0.308 with a lookback time of 3.5 Gyr, using deep JWST/NIRCam photometry. By leveraging observations in eight broadband filters (F070W to F444W), we derive constraints on GC masses, ages, and metallicities of 69 GC candidates, refining previous studies focused on color-magnitude analysis. The inferred GC masses predominantly fall near 10^7 M…

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astro-ph.EP2026年7月24日

JWST/MIRI Reveals the Evolution from Molecular to Atomic Disk Winds

Naman S. Bajaj, Ilaria Pascucci, Sylvie Cabrit, Suzan Edwards, Gabriele Cugno, Andrew D. Sellek, Joan R. Najita, Ke Zhang et al.

The evolution and dispersal of protoplanetary disks--governed by accretion, magnetically launched jets and winds, and photoevaporative winds--fundamentally shape planetary systems. Determining how these mass-loss processes co-evolve is crucial for constraining planet formation pathways. We analyze archival JWST/MIRI/IFU data of 72 inclined (i>40deg) mostly ClassII disks to identify and characterize spatially resolved jets and winds, focusing on [NeII] and H2 lines. Extended emission in H2 S(1),…

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astro-ph.IMastro-ph.EP2026年7月24日

Jointly Modeling Roman Coronagraph Astrometry and Photometry Improves Orbital Parameter Estimates

Farrah Molina, Sarah Blunt, Jason Wang

Launching in 2027, the Nancy Roman Grace Space Telescope (Roman) has the potential to directly image exoplanets in reflected light for the first time. Roman imaging will introduce new constraints on exoplanet orbital parameters, since reflected-light intensity depends on orbital phase. In this Note, we discuss an addition to the open-source Python package orbitize!, which allows users to model exoplanet orbits using joint constraints from astrometry and photometric variations due to orbital phas…

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astro-ph.GA2026年7月24日

Outflows in super-Eddington quasars drive clumpy circumgalactic medium and extended H$α$ nebulae at $z \gtrsim 6$

Lucas Tortora, Tiago Costa, Debora Sijacki, Jake S. Bennett

The discovery of gargantuan black holes with masses exceeding a billion solar masses at $z\gtrsim6$ suggests rapid black hole growth and significant energy input into their host galaxies in the early Universe. With JWST probing previously unseen phases of the interstellar (ISM) and circumgalactic (CGM) medium around $z > 6$ quasars, detailed theoretical studies can now be directly confronted with observations. We use zoom-in simulations of a massive protocluster at $z\sim6$, employing both the f…

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astro-ph.GA2026年7月24日

Megaparsec-Scale Neutral Hydrogen Flows in the Neighborhood of Hickson Compact Group 100

Qingzheng Yu, Taotao Fang, Enrico M. Di Teodoro, Cheng Cheng, Cong Kevin Xu

The evolution of galaxies is strongly influenced by their ability to exchange gas with their surroundings, yet direct observational constraints on these processes remain scarce. Using ultra-deep neutral hydrogen (HI) observations with the Five-hundred-meter Aperture Spherical Telescope (FAST), we detect a diffuse HI structure extending over $\sim$1 Mpc around the compact galaxy group HCG 100, with integrated column densities down to $\sim$$8.6\times10^{17}$ cm$^{-2}$. This structure is among the…

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astro-ph.IM2026年7月24日

Low-cost, ultra-wideband, differential low-noise amplifier for interferometric radio telescopes

Sophia Da Costa, Albert Wai Kit Lau, Keith Vanderlinde

We present a low-cost, ultra-wideband, dual-polarized differential low-noise amplifier that eliminates the need for a pre-amplification balun. Built entirely from commercial surface-mount components, the design costs approximately 20 US dollars per unit. The amplifier has been characterized through laboratory gain and noise measurements together with feed-coupled hot-cold testing at the Dominion Radio Astrophysical Observatory. A noise figure close to 0.3 dB is demonstrated across a 10:1 bandwid…

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gr-qcastro-ph.HE2026年7月24日

Viscosity effects on the shadow of a non-rotating black hole

Sayantani Lahiri, Sergio Gimeno-Soler, Alejandro Cruz-Osorio, José A. Font, Ziri Younsi

We study the effect of shear viscosity in stationary magnetized accretion tori on synthetic images of non-rotating black hole shadows. Shear viscosity and spacetime-curvature contributions are introduced perturbatively in the tori through first and second-order transport coefficients within a second-order causal theory of non-ideal relativistic hydrodynamics. Synthetic black hole shadow images at 230\,GHz are obtained via general relativistic radiative transfer computations assuming thermal sync…

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astro-ph.GA2026年7月24日

The AGORA High-resolution Galaxy Simulations Comparison Project. IX - Part 2: Effects of a Major Galaxy Merger on the Stellar Morphology of a Milky Way-mass Galaxy Progenitor

Thinh Huu Nguyen, Kirk S. S. Barrow, Minyong Jung, Ramón Rodríguez-Cardoso, Santi Roca-Fàbrega, Ji-hoon Kim, Joel R. Primack, Kentaro Nagamine et al.

Galaxy mergers, with their high sensitivity to initial conditions, provide a valuable setting for comparative studies of galaxy simulation codes. Following our first paper focusing on merger-driven star formation, we present a code comparison examining the morphological transformation impact of a major galaxy merger at $z \approx 4.5$ on a Milky Way-mass galaxy progenitor. Our analysis employs nine state-of-the-art codes from the AGORA CosmoRun cosmological zoom-in simulation suite. For this mer…

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astro-ph.GA2026年7月24日

The AGORA High-resolution Galaxy Simulations Comparison Project. IX - Part 1: Effects of a Major Galaxy Merger on Star Formation of a Milky Way-mass Galaxy Progenitor

Thinh Huu Nguyen, Kirk S. S. Barrow, Minyong Jung, Ramón Rodríguez-Cardoso, Santi Roca-Fàbrega, Ji-hoon Kim, Joel R. Primack, Kentaro Nagamine et al.

Given their highly nonlinear dynamics and sensitivity to initial conditions, galaxy mergers are a compelling area to conduct a simulation code comparison. We perform a comparative study of a major galaxy merger at $z \approx 4.5$ in cosmological zoom-in hydrodynamic simulations of a Milky Way-mass galaxy progenitor. The comparison employs the AGORA CosmoRun suite of nine well-calibrated, state-of-the-art numerical codes, each adopting a different stellar feedback scheme. We find that the evoluti…

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cs.LGastro-ph.COastro-ph.GAhep-exhep-ph2026年7月24日

An Introduction to Bayesian and Frequentist Simulation-Based Inference with Machine Learning

Maximilian Dax, Theo Heimel, Gilles Louppe

Simulation-based inference (SBI) with machine learning is an increasingly important tool for solving inverse problems in science and engineering, including parameter inference and the inversion of detector effects. We provide an overview of the Bayesian and frequentist statistical frameworks, describe how machine-learning-based SBI methods, such as neural posterior estimation and neural likelihood estimation, can be used for parameter estimation within these frameworks, and show that the same me…

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astro-ph.GA2026年7月24日

Different paths, same appearance: an intermediate-age red nugget at z~0.13

F. La Barbera, F. Buitrago, I. Ferreras, C. Tortora

Massive ultra-compact galaxies are commonly regarded as nearby relics of the compact quiescent population at z~2-3, and detailed studies have focused so far only on old systems in dense environments. Here we present a spatially resolved analysis of G79071, an ultra-compact (R_e 5Gyr) component. The central metallicity is supersolar and decreases with radius, while most abundance ratios show flat radial trends and are consistent with typical massive, low-redshift ETGs at similar velocity dispersi…

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astro-ph.HE2026年7月24日

XMM-Newton and Swift Unveil Another X-Ray Transient in NGC 4945, XMM J130514.64-493311.27

Ryan W. Pfeifle, Kimberly A. Weaver, Jenna M. Cann, Murray Brightman, Miranda McCarthy

NGC 4945 hosts a Compton-thick, low luminosity AGN and a nuclear starburst in its core and has been the subject of many previous X-ray investigations of the AGN emission structure, nuclear starburst properties, and ultraluminous X-ray (ULX) source populations. Indeed, NGC 4945 has proven to be a rich system for ULX and X-ray transients, with at least four X-ray transients being reported over the last 15 years. Here we report the detection of an X-ray transient source, XMM J130514.64-493311.27, i…

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