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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。

hep-phastro-ph.HE

Boosted Dark Matter Directionality in Large Liquid Scintillator Detectors

Samuel S. H. Tse, Qishan Liu, Kenny C. Y. Ng, Koun Choi, Yu-Feng Li

Light dark matter can be boosted by cosmic-ray-dark matter interactions, which opens the possibility of direct-detection searches with large neutrino detectors. We consider the signal produced by boosted dark matter undergoing quasi-elastic scattering off carbon and knocking out a neutron in a large liquid scintillator detector. A distinctive delayed gamma ray from neutron capture can be reconstructed after $\sim 210$ $μ$s, which is paired up with the prompt signal during neutron propagation. We…

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astro-ph.GAastro-ph.CO

Odd radio circle J1555+2726: Observational evidence for shock re-acceleration of fossil plasma

L. Bruno, B. Koribalski, R. P. Norris, A. Ivleva, T. Venturi, A. Botteon, C. J. Riseley, K. Dolag et al.

Context. Odd radio circles (ORCs) are peculiar extragalactic sources recently discovered. They are characterised by one or more bright rings extending on scales of hundreds of kiloparsecs, and are filled with fainter emission. A massive elliptical galaxy lies at the centre of ORCs. While their formation mechanism is debated, a shock is plausibly involved. Aims. We aim to constrain the nature of ORC J1555+2726 (ORC4) through the analysis of its morphological and spectral properties. Methods. We u…

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astro-ph.SR

Magnetic Activity as a Driver of Low-gravity-like Spectral Morphology in Late-M Dwarfs

Chia-Lung Lin, Daniel Apai, Benjamin V. Rackham, Prajwal Niraula, Mark S. Giampapa, Ana Glidden, Julien de Wit, Valeriy Vasilyev et al.

We present a systematic investigation of the connection between magnetic activity and the low-surface-gravity-like near-infrared spectral morphology of late-M dwarfs. Our sample includes TRAPPIST-1 observed with JWST NIRISS/SOSS and 22 late-M dwarfs observed with IRTF/SpeX, together with flare observations from K2, TESS, JWST NIRISS/SOSS, and literature-reported X-ray luminosities. Using one-component PHOENIX/NewEra spectral modeling, we find that all targets are better reproduced by lower-surfa…

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astro-ph.COastro-ph.GA

A Robust Estimator for the Lyman-$α$ Forest 1D Power Spectrum at High Redshift

Molly Wolfson, Joseph F. Hennawi, Frederick B. Davies, Zarija Lukić

The Lyman-$α$ (Ly$α$) forest flux power spectrum $P(k)$ is sensitive to a range of astrophysical and cosmological effects, including the thermal state of and large-scale fluctuations in the intergalactic medium and the nature of dark matter. Measuring $P(k)$ becomes increasingly challenging at high redshift, where fewer quasar spectra are available and higher Ly$α$ optical depths result in lower transmitted flux. In addition, observational effects and missing data complicate standard Fourier-tra…

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astro-ph.HEastro-ph.SR

Formation and Detectability of PSR J0653+0443-like Extremely Eccentric Binary Neutron Stars in the Milky Way

Zhiwei Chen, Jihui Zhang, Youjun Lu

Recently, the Five-hundred-meter-Aperture-Spherical-radio-Telescope (FAST) Galactic Plane Pulsar Snapshot (GPPS) survey discovers an extraordinary binary neutron star (BNS) system, PSR J0653+0443, possessing the highest known orbital eccentricity ($e\approx0.992$) among Galactic BNSs (Yang et al., 2026), which provides a unique probe into the formation and evolution of BNSs. In this Letter, we perform compact binary population synthesis calculations with self-consistent neutron star spin evoluti…

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math-phastro-ph.GA

Some minimal characteristics and flat trajectories of a system in the N-body problem

Igor Pavlov

For the classical model of a system of N particles with interaction (the N-body problem) we consider some spatial problems of nonlinear programming for finding conditional minima and local extrema for the main characteristics of the system on its phase space. We prove that these conditional minima and local extrema of the system characteristics can only be achieved on flat, in general, not necessarily finite, trajectories of the system in space, (under the condition that the system angular momen…

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astro-ph.HEgr-qc

Charged fluid tori with an approximate magnetic self-field around magnetized Schwarzschild black holes: A semi-analytic approach

Abylaikhan Tlemissov, Jiri Kovar

We study toroidal structures formed by a charged, non-self-gravitating perfect fluid orbiting a Schwarzschild black hole immersed in a poloidal magnetic field. To obtain analytic and semi-analytic solutions, we assume a cold, rest-mass-dominated fluid with uniform specific charge and zero conductivity, so the current is purely convective. This regime is formally opposite to the ideal GRMHD limit. The total magnetic field comprises a prescribed asymptotically uniform external component and an app…

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astro-ph.SR

Granulation-driven spectral irradiance variability of Sun-like stars

N. -E. Nèmec, G. Kopp, V. Witzke, N. M. Kostogryz

Granulation,caused by convection in low-mass stars like the Sun, introduces small amplitude variations in the stellar brightness on timescales of minutes to hours. Often referred to as flicker or microvariability this signal can impede detecting Earth-sized planets around Sun-like stars via stellar transits. Stellar flicker can also introduce uncertainties in determining stellar fundamental parameters and cause errors of up to 10% in the radius determination of transiting exoplanets. Both source…

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astro-ph.IMastro-ph.HE

A Generalized Framework for Rapid Polarization Response Generation in Wide Field-of-View Compton Polarimeters

Mohamed Gamal Zaid, Merlin Kole, Mark McConnell, Fabio Muleri, Hancheng Li

Polarimetry is the most direct probe of the unsettled radiation mechanism and magnetic field structure of gamma-ray burst (GRB) prompt emission at the energies where it peaks, tens of keV to about 1 MeV. Compton polarimeters use the azimuthal scattering angle distribution (ASAD), a 180 degree modulation on axis. GRB measurements have largely relied on the on-axis modulation factor $μ_{100}$. For a wide field-of-view planar polarimeter, GRBs arrive off axis, where the Klein-Nishina projection add…

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astro-ph.GA

SpecLess: A Multi Survey Python Package for Machine Learning Classification of Galaxy Morphology and Activity from Photometry

Uzay Aydin, Mehmet Tanriver

Broad band photometry enables scalable galaxy classification without spectroscopy at inference time, yet strong within survey performance may not transfer when the same galaxies are measured by another survey. We present SpecLess, an open source Python package implementing two photometric classification tasks: high confidence Galaxy Zoo 1 elliptical and spiral morphologies, and four SDSS spectroscopic activity reference classes (starforming, starburst, Seyfert, and LINER). Using SDSS+AllWISE, Ki…

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astro-ph.EP

A Headwind-like Helium Outflow from TOI-3884b

Joe P. Ninan, Jessica Libby-Roberts, Suvrath Mahadevan, Oleg Kochukhov, Daniel M. Krolikowski, Gudmundur Stefansson, Shubham Kanodia, Jaume Orell-Miquel et al.

Constraining atmospheric loss is crucial for understanding the evolution of planetary atmospheres. We report the detection of an evaporating exosphere from TOI-3884b, a super-Neptune in a polar orbit around an M4 dwarf star. We infer this evaporation from a 6.8$\pm$0.27\% excess transit depth in the He I 10830 Å\, line, observed during five transits of TOI-3884b with the Habitable Zone Planet Finder spectrometer. While we observe outflow signatures starting as early as 5 hours before the onset o…

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astro-ph.HE

Prompt Jet Launching and Delayed Thermal Disk in Tidal Disruption Event for Prolonged Activity GRB 220706A

Yuri Sato, Rin Oikawa

GRB 220706A exhibits X-ray flaring activity extending to ~51 days after the trigger, along with a luminous optical thermal component emerging on a timescale of ~10^6 s. Such prolonged central-engine activity could be powered by a collapsar fed by an extended stellar envelope. However, a relativistic jet may struggle to break out of the extended envelope. These challenges motivate a tidal disruption event (TDE), although explaining both the early relativistic jet and the luminous late optical the…

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astro-ph.SRastro-ph.GA

Slow Massive-Star Formation and the O-Star ZAMS Deficit

Paolo Padoan, Samuel Shipkoff, Mark Gieles, Fabrice Martins

The scarcity of optically visible O stars near the theoretical zero-age main sequence (ZAMS) has puzzled astronomers for over four decades. We argue that it reflects prolonged accretion. If massive stars assemble over Myr timescales, as the inertial-inflow model predicts, core-hydrogen burning begins before accretion ends, and the stars become optically visible at the end of accretion on a birthline displaced from the standard ZAMS. We test this interpretation by comparing the hot-side envelope…

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astro-ph.SR

Unexpected Local Enhancement of Chromospheric Moreton Waves on the Sun

Y. W. Ni, J. H. Guo, C. Li, Y. K. Wang, G. Y. Chen, C. Xia, C. Fang, P. F. Chen et al.

Solar eruptions often drive shock waves. When propagating in the solar corona, strong shock waves would leave imprints on the solar surface in the chromosphere, which are called Moreton waves. Moreton waves generally decay as they move away. However, to our knowledge, for the first time we report that a Moreton wave is significantly enhanced midway during propagation, as revealed by the spectroscopic observations from China's first solar satellite, the Chinese H$α$ Solar Explorer. Combining magn…

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astro-ph.IMastro-ph.HE

Simulation-based inference of profile evolution for high-precision pulsar timing

Sai C. Susarla, Gregory Ashton, A. Parthasarathy, K. De Man, J. P. W. Verbiest

Pulsars are exceptional cosmic laboratories, the most stable of which rival atomic clocks. Nearly all of that precision rests on one observable, the average pulse profile unique to each pulsar and stable over decades. These profiles change shape systematically with observing frequency, reflecting the physics of the emitting pulsar beam, but if left unmodelled, it can bias the arrival-time measurements, undermining precision timing. Profile-domain timing has been proposed to address this effect,…

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astro-ph.COastro-ph.HEgr-qchep-ph

Gravitational Wave Diffractive Images Reveal the Structure of Astrophysical Objects

Han Gil Choi, Sunghoon Jung, Volodymyr Takhistov

Scattering patterns encode the structure of extended objects, as demonstrated by charged particle scattering on atomic nuclei. Gravitational wave (GW) diffraction offers an analogous probe of otherwise invisible mass distributions. At linear order in the lens potential we derive expressions relating the central diffractive image contribution to a gravitationally lensed GW waveform to the Fourier transform of the projected lens density. For finite mass lenses this contribution takes the form of a…

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astro-ph.GA

A Catalog of Spectral Properties for DESI DR1 Quasars

Qiaoya Wu, Yue Shen

The Dark Energy Spectroscopic Instrument (DESI) is carrying out a five-year spectroscopic survey designed to map the large-scale structure of the Universe and obtain spectra for millions of galaxies and quasars over a wide redshift range. We present a value-added catalog of spectral properties for 1,717,774 unique quasars (1,774,723 spectra) in the DESI Data Release 1. We perform a uniform spectral decomposition of the quasar continuum, host galaxy emission (at $z 1$ where the pipeline redshift…

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physics.plasm-phastro-ph.HEastro-ph.SR

Synthetic 2D magnetic turbulence with controlled island structuring

Yari De Paep, Daniela Maci, Rony Keppens

Magnetic turbulence remains up to this day not fully understood, despite its important role in the behavior of plasmas. A recurring ingredient in plasma turbulence is the spontaneous formation and evolution of plasmoids. These represent magnetic islands on current sheets in two-dimensional turbulent magnetic fields that are consistently found in high-resolution direct numerical simulations (DNSs) using a magnetohydrodynamic description. However, such simulations require considerable amounts of c…

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astro-ph.HE

FRB 20210601A: Extreme Temporal Clustering in a Repeating Fast Radio Burst Source as Evidence for a Hidden Class of Episodic Repeaters

Ryan Mckinven, Amanda M. Cook, Alice P. Curtin, B. M. Gaensler, Jason W. T. Hessels, Naman Jain, Lordrick Kahinga, Victoria M. Kaspi et al.

Population studies of fast radio burst (FRB) repetition typically model sources using a single distribution of steady, time-averaged burst rates, yet individual sources show significant departures from this assumption. Here we present FRB 20210601A, a source discovered by the Canadian Hydrogen Intensity Mapping Experiment FRB project (CHIME/FRB) that represents the most extreme such departure yet identified. The source produced at least nine bursts within a single 106.5 s interval -- the highest…

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astro-ph.HE

Spectral Properties of X-Ray Flares in Gamma-Ray Bursts

Xiongwei Bi, Zejun Jiang, Jirong Mao

We conducted a systematic spectral analysis of the X-ray flares of gamma-ray bursts (GRBs) observed by Swift/X-ray Telescope from 2005 April to 2015 March. The sample includes 521 flares from 206 GRBs. The GRBs cover the three subtypes: X-ray flashes (XRFs), X-ray-rich GRBs (XRRs), and classical GRBs (C-GRBs). We used a simple power-law model to fit the spectra during the flares, as well as to fit the preflare and postflare afterglow emissions, and obtained the parameters such as photon index an…

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astro-ph.HEastro-ph.IMphysics.comp-ph

Multigroup Radiation Diffusion with Compton Scattering on a Moving Mesh: Implementation in RICH and Application to Tidal Disruption Events

Itamar Giron, Menahem Krief, Elad Steinberg

Compton scattering exchanges energy between radiation and hot gas and changes the spectrum in high-energy astrophysical systems such as tidal disruption events (TDEs). Because it couples all photon energies and can act faster than the hydrodynamic time step, many radiation-hydrodynamics (RHD) simulations omit its spectral redistribution or treat its energy exchange in the gray approximation. We extend the multigroup flux-limited diffusion module of the moving-mesh RHD code RICH to include Compto…

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astro-ph.HE

Breaking the symmetry: X-ray polarization from a spreading layer on a tilted weakly magnetized neutron star

Anna Bobrikova, Alexandra Veledina, Juri Poutanen, Vladislav Loktev

When modeling the emission from an X-ray binary system, we often assume that the rotational axis of the compact object is aligned with that of the binary system. While often considered irrelevant for spectroscopic observations, the orientation of the binary system is crucial for polarimetric properties. With the recent advent of X-ray polarimetric observations enabled by the Imaging X-ray Polarimetry Explorer (IXPE), indications of a possible misalignment of the neutron star rotational axis with…

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astro-ph.IM

Science-driven design and performance evaluation of a Silicon Laue Component lens for hard X-ray polarimetry

L. Abalo, N. M. Barrière, M. W. Beijersbergen

Focusing hard X-rays above 80 keV is challenging for grazing-incidence optics. Laue lenses offer an alternative based on crystal diffraction. We assess a lens based on Silicon Laue Components (SiLCs), consisting of stacked silicon plates, for polarimetry of accreting stellar-mass black holes and strongly magnetized neutron stars in the 80-200 keV band. We derive effective-area requirements from the minimum detectable polarization at 99% confidence (MDP99) for an XL-Calibur-inspired polarimeter o…

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astro-ph.EPastro-ph.IM

The first selection of optimal targets for the Lazuli ExtraSolar Coronagraph's reflected starlight exoplanet campaign

Logan A. Pearce, Ewan Douglas

Direct detection and characterization of exoplanet atmospheres via reflected starlight enables probes of composition of mature exoplanet systems (since flux is decoupled from age) at closer separations than via thermal emission (due to observations in visible wavelengths), and even probes of biosignatures. New and upcoming ground and space-based platforms are enabling these observations for the first time. Recently the 3-m Lazuli Space Telescope, from the Eric and Wendy Schmidt Observatory Syste…

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astro-ph.SR

Analysis of a coronal hole jet in the chromosphere and the transition region with IRIS data and SDO observations

M. Koletti, C. Gontikakis, S. Patsourakos, K. Tsinganos

Coronal jets are transient phenomena that occur throughout the solar atmosphere, often triggered by the activation of mini-filaments. Jets are an important field of study, as they are believed to contribute to the mass supply of the solar wind. We study a small-scale solar jet occurring in a low-latitude coronal hole, focusing on traces of the jet eruption to the lower atmosphere, utilizing chromospheric and transition region diagnostics. We also investigate the possible mechanisms and dynamic c…

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astro-ph.HE

In Search of the Gravitational Wave of Fast X-Ray Transient in the Second Part of the LIGO-Virgo-KAGRA Fourth Observing Run

Po-Ya Wang, Albert K. H. Kong, Surojit Saha

Fast X-ray Transients (FXTs) are brief, intense X-ray flashes unassociated with persistent X-ray sources or known stellar objects, typically lasting from seconds to hours. With the launch of the Einstein Probe in January 2024, the study of FXTs has entered a new phase. Its large field of view significantly increases the discovery rate, enabling more robust statistics. The leading discoveries have revealed a fraction of gamma-ray bursts, while the rest remain unexplained. We propose a methodology…

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astro-ph.SR

Eight new, triply eclipsing triple star systems

T. Borkovits, S. A. Rappaport, G. Torres, A. Tokovinin, T. Mitnyan, R. Gagliano, T. Jacobs, B. Powell et al.

We have identified numerous triply eclipsing hierarchical triple star systems from observations made with the space telescope TESS. For many of these systems we can potentially determine their dynamical and astrophysical parameters with high precision, in some cases even without the use of radial velocity data. In the present paper we report the comprehensive study of eight new, triply eclipsing triple star systems, taken from this larger sample: TICs 77177148, 220456364, 232874003, 306690194, 3…

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astro-ph.HEastro-ph.GA

The XMM-Newton view of the DEM L36 superbubble in the Large Magellanic Cloud

Pawel M. Janas, Patrick J. Kavanagh, Manami Sasaki, Miroslav D. Filipović, Chandreyee Maitra, Frank Haberl, Pierre Maggi, Sean Points et al.

We present the first multi-wavelength analysis of the DEM L36 superbubble in the Large Magellanic Cloud. We compare the DEM L36 superbubble with other Galactic and Magellanic Cloud superbubbles. We use data from XMM-Newton, supplemented by data from the Magellanic Cloud Emission Line Survey, the Dark Energy Camera Magellanic Cloud Emission Line Survey, the Spitzer Space Telescope, and the Australia Telescope Compact Array. We perform a multi-wavelength morphological analysis to understand the sh…

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astro-ph.COastro-ph.GAastro-ph.IM

A cosmic filament catalog for COSMOS-Web Data Release 1 across 0.5 < z < 3.5

Qiaoyang Hao, Tao Wang, Weishan Zhu, Hong Guo, Peng Wang, Tiancheng Yang, Luwenjia Zhou

Cosmic filaments represent the environments in which most galaxies form and evolve. However, the spatial distribution of filaments and the link between galaxy properties and their positions relative to filaments remains unclear, particularly at high redshifts. In this work, using the deep-field catalog COSMOS-Web Data Release 1, we construct a filament catalog spanning 0.5 < z < 3.5 that can be directly applied to studies of galaxy evolution and the galaxy--large-scale-structure connection at th…

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astro-ph.GA

Self-Supervised Representation Learning for JWST Galaxy Images and Low Resolution Spectra

Yang Cheng, Morgan Fouesneau, Ivelina G. Momcheva, Tobias Buck, Shengxiu Sun

A self-supervised multimodal model recovers galaxy stellar masses from sparse JWST data that lack the multi-band coverage required by traditional SED fitting. We train on single-band F150W imaging paired with observed-frame 1-2 $μ$m PRISM spectra and obtain a joint image-spectrum representation that recovers stellar mass at $1<z\le3$ with $R^2 \sim 0.9$ and $σ_{\mathrm{NMAD}} = 0.24$ dex; cross-modal CLIP alignment further raises single-modality performance by $ΔR^2 = +0.04$ (imaging) and $+0.09…

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