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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。

physics.pop-phastro-ph.IMphysics.opticsphysics.space-ph

Project Setu: 3D Multi-Physics Design and Scaled Structural Analysis for a Relativistic Lightsail Architecture

Prashant Suresh Kamble

Deep-space exploration beyond the solar system requires eliminating chemical propellant mass penalties to achieve relativistic flight velocities (0.166c at 180 s, reaching the mission target of 0.20c at 227 s). This study presents a 3D multi-physics numerical framework for a 4.0-meter circular lightsail propelled by a 100 GW ground laser array, coupling 3D Maxwell FDTD wave optics, non-linear membrane mechanics, and Stefan-Boltzmann thermal radiation in ANSYS Mechanical APDL and Ansys Lumerical.…

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astro-ph.HEgr-qc

An HLLD Implementation for General Relativistic Magnetohydrodynamics in AthenaK

Jacob Fields, George N. Wong, James M. Stone

We present an implementation of an HLLD approximate Riemann solver for the AthenaK astrophysics code with support for full general relativistic magnetohydrodynamics via a tetrad frame transformation. Our implementation uses an initial guess for the HLLD iterative solve which eliminates the need for an additional conserved-to-primitive inversion, which greatly accelerates performance without affecting accuracy. Additionally, by coupling the method with a first-order flux correction, we are able t…

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astro-ph.EPastro-ph.GA

Shaving the Outskirts of Planetary Systems Probed by Roman via Stellar Flybys

Donald Liveoak, Tim Hallatt, Sarah Millholland

The recently launched Nancy Grace Roman Space Telescope (\textit{Roman}) will soon begin observations that promise to revolutionize our understanding of exoplanet demographics. \textit{Roman}'s Galactic Bulge Time-Domain Survey (GBTDS) will observe the Galactic Bulge via transit and microlensing techniques, providing a unique opportunity to study hot Jupiters as well as long-period/free-floating exoplanets in a dense and kinematically hot stellar environment. In this Letter, we quantify how repe…

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astro-ph.GA

FAST Observations of Filamentary and Compact H I Structure in a Magellanic Stream IV Field

Yuxin Xiao, Qingzheng Yu, Taotao Fang, Di Li, Shulan Yan, Shuo Zhang

The Magellanic Stream (MS) is believed to have formed from gas removed from the Large and Small Magellanic Clouds through tidal forces and hydrodynamic interactions with the Milky Way's gaseous halo. It provides an important laboratory for studying how stripped gas fragments, mixes, and evolves in a circumgalactic environment. In this work, we present HI observations of a $3.8^\circ\times2.2^\circ$ field in the MS IV region, using the data from the Commensal Radio Astronomy FasT Survey (CRAFTS).…

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astro-ph.HEgr-qc

The accuracy of merger times in hierarchical black hole triples

Giulia Fumagalli, Alejandro Vigna-Gómez

Orbit-averaged equations are widely used to model the gravitational-wave-driven evolution of compact binaries. Their validity relies on the radiation-reaction timescale being much longer than the orbital period, an assumption that can break down for highly eccentric systems. In this work, we investigate the impact of orbit averaging on merger-time estimates by comparing orbit-averaged and non-orbit-averaged prescriptions. We apply our analysis to two different astrophysically motivated populatio…

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gr-qcastro-ph.HE

Physics-based phenomenological modeling of binary black hole hierarchical formation 1: Synthetic universes from globular cluster simulations for GWTC

R. O'Shaughnessy, R. Mechum, M. Qazalbash, Z. Rosenberg, M. Zeeshan

We iteratively model the GWTC-5.0 binary-black-hole census with three components. First, a physically normalized population from Rapster globular-cluster simulations spans cluster mass, metallicity, formation redshift, compactness, and natal black-hole spin. Hierarchical mergers reproduce higher-mass events and their larger effective-spin dispersion, provided black holes are born with zero natal spin. Second, a phenomenological field (isolated-binary) channel supplies the low-mass, preferentiall…

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gr-qcastro-ph.GAastro-ph.IMhep-ph

Self-supervised reconstruction of transients in data from space-borne gravitational-wave detectors

Yuxiang Xu, Minghui Du, Bo Liang, Zihao Xiao, Tianyu Zhao, Peng Xu

Space-based gravitational-wave (GW) data may contain transient signals whose waveform morphologies are not known in advance. Extracting these signals is important for characterizing new sources and mitigating instrumental anomalies. However, existing deep neural network (DNN)-based extraction approaches rely on clean training targets and waveform-class-specific examples, which may limit their applicability when the transient morphology is not specified in advance. This work develops a Noise2Nois…

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astro-ph.SRastro-ph.HE

Magnetically Confined Mountains on Accreting White Dwarfs

Pedro H. B. Rossetto, Manoel F. Sousa, Diego A. Falceta-Gonçalves

The hydromagnetic structure of magnetically confined mountains on accreting white dwarfs is computed, alongside the effects of accretion on the reduction of the star's magnetic field. The equilibrium structure of the mountain is obtained by numerically solving the Grad-Shafranov equation with a self-consistent scheme that enforces magnetic flux freezing. For characteristic system parameters, it is shown that magnetic field lines are significantly deformed and dragged equatorwards by mountains wi…

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astro-ph.SRastro-ph.GA

A Uniform Census of Variable Stars in M101 Based on HST/ACS Photometry

Jiyu Wang, Xiaodian Chen, Pinjian Chen, Jianxing Zhang, Shu Wang, Licai Deng

We present a homogeneous HST/ACS F555W/F814W time-series census of variable stars in two M101 disk fields, using a uniform multi-band reduction and reproducible variable-selection workflow for nearby SN-host galaxies. Supplementary archival F555W epochs are used only to refine selected long-period solutions. Candidates are selected with Lomb-Scargle period searches, Fourier light-curve modeling, two-band consistency statistics, artificial-star-test photometric corrections, and mode-aware Cepheid…

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eess.SPphysics.space-ph

Wideband HF Skywave Propagation: A Review with Link Modeling Corroborated by Propagation Data

Eric Weber, Ted Nowak, Joseph Berg, Nader Behdad

The high-frequency (HF) band, ranging from 3 to 30 MHz, is widely used in a number of applications such as beyond-line-of-sight (BLOS) communications and over-the-horizon radar systems. The long-range propagation characteristics of the HF band rely on the Earth's ionosphere as a refracting medium to establish BLOS wireless links. However, traditional HF communications links often use channels with narrow bandwidths (typically 3 kHz), which limits the amount of data that can be transmitted. In th…

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nucl-thastro-ph.HE

Hadron resonance gas with density-dependent interactions for neutron stars and heavy-ion collisions

Volodymyr Vovchenko, Volodymyr Kuznietsov, Tripp Moss

We present a density-dependent generalization of the van der Waals hadron resonance gas model (DD-HRG) for describing both the hot hadronic matter created in heavy-ion collisions and the cold, dense matter inside neutron stars. Non-resonant interactions are incorporated through a generalized excluded-volume prescription with a density-dependent available-volume fraction, supplemented by an arbitrary density-dependent mean field. With isospin-dependent interaction parameters constrained by empiri…

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astro-ph.HE

A Possible X-ray and Gamma-ray Quasi-Periodic Oscillation in GRB 241030A

Noel Klingler, Cecilia Chirenti, M. Coleman Miller, Amy Lien, Simone Dichiara

Quasiperiodic oscillations (QPOs) in gamma-ray intensity have been reported from a few gamma-ray bursts. These QPOs could be related to fundamental frequencies in the sources, which would lead to new insights about these systems. Here we report on our analysis of GRB~241030A, a several-minute-long burst with $\sim 10$ gamma-ray flares that have approximate periodicities at f ~ 0.04 Hz and f ~ 0.08 Hz. This quasi-periodicity is seen in X-rays with the Swift X-Ray Telescope (XRT) as well as in gam…

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astro-ph.SRastro-ph.GA

Unresolved triple systems in the aged open cluster Trumpler 19: Discovery, confirmation, and implications

D. Minniti, R. K. Saito, V. D. Ivanov, C. O. Obasi, P. W. Lucas, J. G. Fernández-Trincado, J. Alonso-García, E. R. Garro et al.

It is difficult to identify unresolved triple and higher-order systems beyond the solar vicinity. Star clusters yield controlled environments with known physical parameters, providing a way to explore homogeneous stellar samples. Combining modern optical and near-IR surveys, our main goal is to explore the region of the color-magnitude diagrams located above the sequence of equal-mass binaries, which is inhabited by unresolved triple and quadruple systems. Specifically, here we aim to discover a…

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astro-ph.GA

Tracing the Hidden Molecular Gas in the Small Magellanic Cloud with SOFIA and APEX

K. Rodriguez-Ambler, R. Herrera-Camus, M. Rúbio, A. D. Bolatto, D. Riquelme-Vásquez, K. Jameson, C. Muñoz-López, E. J. Tarantino et al.

In low-metallicity environments, reduced dust abundance weakens molecular cloud shielding against far-ultraviolet radiation, enhancing CO photodissociation and producing extended CO-faint or CO-dark molecular gas. The [CII] 158 $μ$m line is a key tracer of these CO-faint phases. We characterize the multiphase origin of [CII] emission and quantify the CO-faint molecular gas fraction across several regions of the Small Magellanic Cloud (SMC), the nearest low-metallicity ($\sim 0.2 Z_\odot$) galaxy…

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astro-ph.GA

Reigniting the FUSE I: Star Formation in Massive Elliptical Galaxies

Michael Reefe, Michael McDonald, Eric Miller, Thomas Brown

In this inaugural paper of our "Reigniting the FUSE" series, we present the data collection & reduction, methodology, and preliminary results for a comprehensive and homogeneous reanalysis of all 30 massive elliptical galaxies that have archival far-ultraviolet (FUV) spectra with the Far Ultraviolet Spectroscopic Explorer (FUSE). We perform SED fitting to these spectra, with aperture-matched photometry from GALEX, SDSS, DES/DECaLS, 2MASS, and WISE, and construct a catalogue of high quality const…

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gr-qcastro-ph.HEhep-th

Effective Field Theory of Gravity in Relativistic Media

Beka Modrekiladze

We develop an effective field theory of gravity in relativistic media. Integrating out the medium leaves vacuum gravity with updated Feynman rules: a graviton propagator dressed by the stress-energy two-point function of the environment, medium-induced bulk graviton vertices from higher correlators, and generalized worldline couplings encoded in matched Wilson coefficients. The diagram topologies are unchanged from vacuum, so different media (perfect fluids, collisionless matter, coherent scalar…

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astro-ph.SRastro-ph.GAastro-ph.IM

Calibration of the Next Generation Palomar Spectrograph as a Stellar Speedometer

Pranav Nagarajan, Kareem El-Badry

We calibrate the Next Generation Palomar Spectrograph (NGPS) for precision stellar radial-velocity (RV) measurements using repeated observations of 24 Gaia-ESO RV standards spanning $G=11$-$18$. Because NGPS is mounted at the Hale telescope's Cassegrain focus, changes in instrumental flexure produce wavelength-solution shifts of tens of km s$^{-1}$, with substantial time and wavelength dependence. We develop a pipeline that measures these shifts directly from each science exposure, using telluri…

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astro-ph.HEastro-ph.GA

Rapid radio variability in the $z\sim7$ blazar VLASS J0410$-$0139: Indication of a hidden population of weak radio jets at Cosmic Dawn

Silvia Belladitta, Eduardo Bañados, Anniek J. Gloudemans, Timothy W. Shimwell, Emmanuel Momjian, Huib Intema, Chiara Mazzucchelli, Christian Fendt et al.

Doppler boosting allows blazars to be detected out to high-$z$, making them promising probes of the intergalactic medium through the 21 cm forest. We report 0.144$-$11 GHz observations of the most distant known blazar, VLASS J041009.05$-$013919.88 at z$\sim$7, obtained with the upgraded Giant Metrewave Radio Telescope (uGMRT), the LOw Frequency ARray (LOFAR) and the Very Large Array (VLA). The first uGMRT epoch (300$-$820 MHz, April 2023) revealed an inverted radio spectrum which, combined with…

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astro-ph.GA

LOFAR radio properties of quasars hosting Extremely High Velocity Outflows

Amy L. Rankine, Paola Rodríguez Hidalgo

Quasar winds are a potential contributor to the radio emission observed in the so-called 'radio-quiet' quasars. Extremely High Velocity Outflows (EHVOs), with bulk velocities >0.1c, represent some of the most energetic of these winds. In this work, we investigate the radio properties of quasars hosting EHVOs in order to assess whether such high-velocity winds contribute to the observed radio emission. We cross-match the catalogue of EHVOs from the Sloan Digital Sky Survey with the high-sensitivi…

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astro-ph.SRastro-ph.EPastro-ph.GA

Deep H$α$ Imaging Survey of IC 348 with the Hubble Space Telescope: I. Accretion Properties of Stellar and Substellar Objects

Lillian Yushu Jiang, Brendan P. Bowler, Yifan Zhou, Adam L. Kraus, Sean M. Andrews, Lynne A. Hillenbrand, Michael J. Ireland, Zhaohuan Zhu et al.

Accretion governs the growth of young stars and the early evolution of their circumstellar disks, yet population-level measurements of accretion are often hampered by heterogeneous diagnostics and by samples preferentially selected toward disk-bearing or accreting objects. This can impact the mass accretion rate-stellar mass ($\dot{M}$-$M_\star$) relation, particularly at substellar masses. We present a uniform analysis of accretion in the $\sim$2 Myr-old star-forming cluster IC 348 based on dee…

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astro-ph.EPastro-ph.IM

Rotational broadening of exoplanet spectra in arbitrarily oriented systems: Application to reflected light

Sophia R. Vaughan, Laura Kreidberg

Exoplanet reflection spectra contain a wealth of information, which we are now beginning to access. At a high spectral resolution, the rotation of both the star and the planet affects the shape of the reflected spectral lines. This effect must be accounted for in high-resolution analyses and could be used to measure the orbital alignment of systems. In this work, we derive the rotational broadening kernels for arbitrarily aligned systems, both for the stellar spectrum viewed by the planet and fo…

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astro-ph.GAastro-ph.CO

Halo mass, star formation, and morphology in galaxies: A morphology-dependent connection between halo environment and star formation activity

G. Mountrichas, F. Shankar, F. J. Carrera, A. Georgakakis

Understanding the mechanisms responsible for quenching star formation in galaxies requires disentangling the roles of internal structure and large-scale environment. We investigate how galaxy morphology and specific star formation rate (sSFR) relate to the typical masses of host dark-matter halos (DMHs), and whether the halo--star formation connection depends on morphology. We analyse non-active galaxies in the VIPERS and Stripe 82 fields at $0.5 \leq z \leq 1.2$, combining DESI-based Sérsic cla…

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astro-ph.SRastro-ph.GAastro-ph.IM

Unresolved Binary Systems in the Rubin Era I: An Autoencoder Framework for Binary Identification Applied to 47 Tucanae

Tobias Géron, Alexander Laroche, Joshua S. Speagle, Maria R. Drout

Binary systems are extremely common and influence many areas of astrophysics, such as stellar evolution and cluster dynamics. In this work, we introduce flexAE, a framework that combines a classical autoencoder architecture with a dedicated classifier component. It is designed to distinguish between single stars and binary systems based on their broadband spectral energy distributions, using all available photometry simultaneously while accounting for observational uncertainties. We demonstrate…

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astro-ph.GA

A direct measurement of the tilting rate of the Milky Way disc

Guillaume F. Thomas, Benoit Famaey, Alicia Rivero, Giuseppina Battaglia, Rodrigo Ibata

The Milky Way disc is typically described, at lowest order, as a flattened rotating stellar component with a fixed spin axis. However, interactions and mergers with smaller galaxies are expected to have an impact on the disc properties. Such interactions can leave long-lasting signatures within galactic discs, including warps and corrugation waves that have already been detected in the Milky Way, but also a slow reorientation of the disc known as tilting, which has never been directly measured u…

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astro-ph.GA

Discovery of Very Minor Merger-Induced Star-forming Clumps at $z=3.33$ with JWST

Alexander de la Vega, Bahram Mobasher

High-redshift galaxies often contain ''clumps:'' compact, $\sim$kpc-scale regions of intense star formation. These substructures make up significant fractions of the masses and star-formation rates of their host galaxies and are expected to affect the morphologies of their hosts, such as by building up bulges. Studying clumps can therefore inform theoretical models of galaxy evolution. Two main mechanisms have been proposed for their formation: gas fragmentation from disk instabilities and compr…

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astro-ph.IMastro-ph.CO

Fast Lensing And Sub-minute High-accuracy photometry (FLASH) with JWST: Pipeline and Primordial Black Hole Microlensing Constraints from M31

David Rubin, Istvan Szapudi

Minute- and sub-minute microlensing provides a direct probe of compact dark matter at asteroid-mass scales, where primordial black holes with MPBH <~ 10^-10 Msol would produce short-duration, finite-source-suppressed amplifications of stars in extragalactic fields. To enable these measurements, we present FLASH: Fast Lensing And Sub-minute High-accuracy photometry with JWST, a pipeline designed to recover such events from JWST/NIRCam imaging by preserving detector-ramp time information and perfo…

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astro-ph.SRastro-ph.GAastro-ph.HE

The youngest white dwarf companion to a millisecond pulsar: Insights from NGC 362D

Greta Ettorre, Emanuele Dalessandro, Mario Cadelano, Alessandro Ridolfi, Cristina Pallanca, Paulo C. C. Freire, Vivek Venkatraman Krishnan, Maurizio Salaris et al.

We report on the identification of the optical counterpart to the recently discovered millisecond pulsar (MSP) NGC362D in the Galactic globular cluster NGC362 based on deep, multi-band, and multi-epoch Hubble Space Telescope observations. Our analysis robustly shows that this object is a very low-mass ($\sim0.18 M_{\odot}$) He white dwarf (WD) still in the pre-cooling phase. Interestingly, a detailed comparison with updated binary evolution models indicates that this object completed the mass-tr…

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astro-ph.SR

Evidence for Enhanced Helium Enrichment from Asteroseismology

Miqaela K. Weller, Marc H. Pinsonneault, Jennifer A. Johnson, Charles Shunyu Yao

The helium abundance of a star has a dramatic effect on luminosity, internal structure, and evolutionary timescales, yet direct helium measurements are unavailable for most stars. In this work, we infer stellar helium abundances by comparing observed and predicted luminosities for a sample of subgiants with asteroseismic masses from the APOKASC sample and spectroscopic parameters from recent survey compilations. Stellar luminosities are predicted using grids of theoretical stellar evolution mode…

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gr-qcastro-ph.IM

A compact time-frequency representation for gravitational-wave data analysis

Noah Pearson, Mesut Çalışkan, Sophie Bini, Neil J. Cornish

Time-frequency (wavelet) domain analyses are seeing greater use for gravitational-wave data analysis due to the advantages they have in handling non-stationary noise. A popular choice is the Wilson-Daubechies-Meyer (WDM) wavelet transform, which uses a window function that is very compact in frequency, but more spread out in time. In this work, we consider an alternative window function that is built from a sum of phase-shifted Gaussians. This "Gaussian" window is more symmetric in time-frequenc…

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astro-ph.GAhep-ph

Baryon-Accelerated Core Collapse in SIDM Halos and its Imprint on Galactic Disks

Zeineb Mezghanni, Elliot Y. Davies, Adriana Dropulic, Gonzalo Herrera, Abdelaziz Hussein, Lina Necib

The gravitational coupling between dark matter (DM) halos and the baryonic structures they host is one of the most powerful windows into the particle nature of DM. Self-interacting dark matter (SIDM) presents a minimal, well-motivated extension to the dark sector with dramatic consequences for the structure of galaxies and their halos. However, the impact of baryons on SIDM halo evolution and the resulting galactic structure has been underexplored in Milky Way (MW)-size galaxies. In this paper,…

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