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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.GAastro-ph.HE

Time-Domain Dust Astrophysics. II. TransRAT: Time-Dependent Grain Alignment and Disruption by Cosmic Transients and Their Observational Signatures

Thiem Hoang

We introduce {\it TransRAT}, a self-consistent time-domain framework that follows the coupled dynamical response of dust to transient irradiation and predicts its observable signatures. We apply {\it TransRAT} to a Type~IIP supernova illuminating a one-zone molecular cloud. Radiative heating raises the grain temperature, modifying the magnetic susceptibility and Larmor precession, while the enhanced radiation field accelerates radiative precession and can switch the alignment axis from the magne…

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astro-ph.GA

Phase-Spirals Across Galactic Disks II: Using large-scale "macro-spirals" in phase-spiral amplitude to derive perturbation times

Kiyan Tavangar, Kathryn V. Johnston, Jason A. S. Hunt, Axel Widmark, Vandana G. Kaushik, Adrian M. Price-Whelan

Phase-space spirals in the Milky Way disk are a key observable remnant of recent perturbations to the Galaxy. They provide insight into the disk's potential, dynamical evolution, past interactions, and even substructure. However, the complex dynamics of phase-spiral formation and evolution have made clear interpretations challenging. For example, recent work has shown that the "winding time" -- measured from how tightly wound a phase-spiral is -- is a biased estimate of the true time since the i…

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astro-ph.HEastro-ph.GA

First Detection of Radio Polarization During Jet Formation in the Changing-Look AGN 1ES 1927+654

Onic I. Shuvo, Eileen T. Meyer, Sibasish Laha, Agniva Roychowdhury, Dev R. Sadaula, Tracy E. Clarke, Wendy M. Peters, Mitchell C. Begelman et al.

We present a multiwavelength radio study of the changing-look AGN 1ES 1927+654 following its renewed X-ray brightening since mid-2022, combining VLBA imaging with multi-band and time-resolved VLA observations. Our main results are: (i) VLBA observations continue to reveal the bipolar jet structure first reported in Meyer et al. (2025), with new X-band detections confirming the morphology at larger separation and K-band imaging revealing a bridge of emission consistent with a continuous outflow;…

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gr-qcastro-ph.HEhep-th

From driven oscillations to free ringdown: a particle plunging into Kerr

Colin Weller, Andrew Laeuger, Fulin Li, Neil Lu, Rowina S. Nathan, Sizheng Ma, Yanbei Chen, Ling Sun et al.

We show that a ringdown waveform can admit a constant-coefficient quasinormal-mode (QNM) representation while its individual QNM-pole contributions remain driven. To establish this result, we construct a first-principles rational approximation to the Kerr Green's function from its QNM poles, physical residues, and horizon-frequency zeros. For particles plunging from the innermost stable circular orbit into Kerr black holes with spins 0.5-0.9, each QNM-pole contribution initially follows the sour…

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nucl-thastro-ph.HEhep-ph

MUSES workflows for pQCD constraints on dense matter with finite quark masses

Isabella Danhoni, Mateus Reinke Pelicer, Débora Mroczek, Yumu Yang, Mauricio Hippert, Jacquelyn Noronha-Hostler

We present a modular implementation of next-to-leading order (NLO) perturbative QCD (pQCD) thermodynamics with finite strange quark mass in the MUSES Calculation Engine, enabling reproducible connections between high-density QCD calculations and neutron star observables. Using this implementation, we investigate the interplay between flavor symmetry and physically motivated renormalization-scale prescriptions in cold, $β$-equilibrated quark matter. We compare prescriptions associated with the co…

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astro-ph.HEastro-ph.SR

Multi-Wavelength Identification of a Luminous Mid-Infrared Supernova Powered by Circumstellar Interaction with Binary-Driven Pre-supernova Mass Loss

Kohki Uno, Kishalay De, Geoffrey Mo, Viraj Karambelkar, Kaitlyn Shin, Christoffer Fremling, Jesper Sollerman, Daichi Hiramatsu et al.

Terminal mass-loss in massive stars is commonly reconstructed from observations of circumstellar interaction in core-collapse supernovae (CCSNe); however, such signatures can be easily missed depending on the phase when they appear. In this paper, we present a multi-wavelength study of SN\,2022yyz, a nearby CCSN selected by its luminous late-time mid-infrared (MIR) excess in NEOWISE at $> 500$ days after the discovery. Classified as a Type II SN at discovery, it reached a peak bolometric luminos…

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astro-ph.SRastro-ph.HEphysics.space-ph

On modelling the 2017 galactic cosmic ray depression

O. P. M. Aslam, D. MacTaggart, M. S. Potgieter, M. D. Ngobeni, I. I. Ramokgaba

In the second half of 2017, as Solar Cycle 24 approached its minimum, a pronounced and rigidity-dependent depression in the galactic cosmic ray (GCR) proton flux was observed using AMS-02. This event was driven by a sequence of strong coronal mass ejections (CMEs). In this work, we model the modulation of GCR protons during this period using a steady-state Parker transport framework with parameters constrained by AMS-02 observations. Treating the event as a purely long-term modulation interval y…

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gr-qcastro-ph.IM

Space-Based Lock-In Determination of Newton's Gravitational Constant

Ulrich D. Jentschura

Inspired by a recent ground-breaking space-based measurement of Newton's gravitational constant, we outline a proposal for a general layout of an optimized space-based approach that combines the advantages of a largely disturbance-free environment with lock-in techniques, null coordinates and the method of covariances. The method of covariances, and cross-covariances, is used for an optimized statistical analysis of data originating from two distinct experimental channels. One of two distinct me…

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astro-ph.EPastro-ph.IMastro-ph.SR

Detecting White Dwarf Exoplanets in the Roman Era

Zifan Lin, Tansu Daylan

White dwarfs (WDs) provide an unparalleled opportunity for detecting and characterizing exoplanets because of the large planet-to-star size ratio. However, only one transiting WD exoplanet is confirmed to date, and occurrence rate constraints remain loose because the rapid transits and weak phase curve modulations of WD exoplanets require high-precision, high-cadence photometry. The Galactic Bulge Time Domain Survey (GBTDS) of the Nancy Grace Roman Space Telescope will provide exactly this by ob…

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physics.ao-phastro-ph.EPphysics.flu-dyn

Scale analysis for the Madden$-$Julian oscillation

Hing Ong

This study performs a scale analysis for the dynamics of equatorial flow systems like the Madden$-$Julian oscillation (MJO). This analysis makes three assumptions about the geometry of the flow and focuses on the leading order terms of the mass continuity and momentum equation system. First, the flow is meridionally narrow. Second, the zonal structure is planetary wavenumber 1. Last, the flow is vertically shallow. When constrained by these geometric assumptions, the system shows a time scale mu…

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astro-ph.EPastro-ph.IM

Earth-Projected Clustering of Historical Optical Transients in the Palomar Observatory Sky Survey-I (POSS-I)

Stephen Bruehl, Beatriz Villarroel, Hichem Guergouri, Brian Doherty, Alina Streblyanska

Palomar Observatory Sky Survey-I (POSS-I) images obtained before the launch of Sputnik contain star-like point sources consistent with sub-second flashes that are absent from all subsequent observations. The nature and origin of these transients remain poorly understood. Based on models suggesting they are in geosynchronous orbit, we estimated the latitude/longitude over which POSS-I transients appeared. From a dataset of 107,875 POSS-I transients, we selected a subset with high probability of r…

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astro-ph.GAastro-ph.IM

JWST Spectra Conclusively Show an Excess of Neutral Gas Outflows in Quiescent Galaxies at z=2-5

Rion Oh, Gourav Khullar, Arianna S. Long, Julissa Sarmiento, Hollis B. Akins, Caitlin M. Casey, Yingjie Cheng, Andreas L. Faisst et al.

Galaxies exhibit a broad range of star formation activity, from actively star-forming to quiescent systems. Yet, the mechanisms responsible for the rapid shutdown and continued suppression of star formation remain poorly understood, particularly for the quiescent galaxies recently uncovered by JWST at $z>3$. Neutral gas outflows provide a direct tracer of gas removal and regulation in quiescent galaxies. We therefore present a NaID $λ\lambda5891,5897$ absorption--line stacking analysis of 274 ga…

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astro-ph.GA

Characterization of Orbits in Bars in Disc Galaxies Using Fourier Frequencies

A. Silva-Castro, I. Puerari, D. Valencia-Enríquez

Bars are among the most prominent dynamical structures in disc galaxies, yet their long-term evolution and the orbital families that sustain them remain only partially understood. In this work, we introduce a new methodology based on frozen potentials combined with Fourier analysis of particle trajectories to identify regular and sticky orbits in self-consistent $N$-body simulations. This approach allows us to isolate particles belonging to the $x_1$ family, directly associated with the bar, and…

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astro-ph.GA

Characterization of Orbits in Bars in Disc Galaxies Using Fourier Frequencies

A. Silva-Castro, I. Puerari, D. Valencia-Enríquez

Bars are among the most prominent dynamical structures in disc galaxies, yet their long-term evolution and the orbital families that sustain them remain only partially understood. In this work, we introduce a new methodology based on frozen potentials combined with Fourier analysis of particle trajectories to identify regular and sticky orbits in self-consistent $N$-body simulations. This approach allows us to isolate particles belonging to the $x_1$ family, directly associated with the bar, and…

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astro-ph.HE

Evolution of Main Sequence Stars Transferring Mass to a Supermassive Black Hole

Andrey Sandomirsky, Re'em Sari, Aleksandra Olejak, Selma E. de Mink

We consider main-sequence stars orbiting close to a supermassive black hole (SMBH), which are potential gravitational wave (GW) sources for LISA if their orbital periods are of the order of an hour. At such a short orbital period, mass transfer from the star to the SMBH occurs. The evolution of the semi-major axis and GW frequency depends on the evolution of the stellar mass and radius. We use MESA to study stars that transfer mass to SMBHs similar to Sagittarius A* starting on the zero-age main…

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astro-ph.SR

Cycle Variation in the Occurrence of Great Soft X-ray Solar Flares

V. N. Obridko, M. M. Katsova, D. D. Sokoloff

Powerful nonstationary processes such as flares and coronal mass ejections are detected mainly near the solar cycle maxima. However, the analysis of the great flares since 1975, when the GOES monitoring started, leads us to more precise conclusions. We have traced the latitudinal distribution of X-class flares and their dependence on the phase of the cycle throughout four cycles. Besides, we compared directly their positions with the magnetic field structure. It was found that the relatively wea…

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

TDCOSMO XXX: Spatially resolved kinematics of the deflectors in time-delay lens systems B1608+656 and SDSSJ1206+4332 from JWST-NIRSpec observation

Pritom Mozumdar, Shawn Knabel, Anowar J. Shajib, Tommaso Treu, Michele Cappellari, Aymeric Galan

We present spatially resolved stellar kinematics of the deflector galaxies in two time-delay lens systems, B1608+656 and SDSS J1206+4332, measured from JWST NIRSpec integral field spectroscopy. B1608+656 is a quadruply imaged quasar lensed by a pair of tidally interacting galaxies, the primary deflector (G1) and a close companion (G2), for which we quantified G2's tidal influence on G1 and define a criterion identifying the region where this perturbation is negligible and standard Jeans-equation…

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astro-ph.EP

Beyond Pebble Isolation: Diverse Pathways to Giant Planet Formation Across Stellar and Orbital Scales

Lorenzo Peerani, Sho Shibata, Ravit Helled

Context. Giant planet formation requires reaching crossover mass, i.e., when the mass of the gaseous envelope becomes equal to the mass of the core, within the disc's lifetime. The formation process depends critically on the orbital distance and stellar mass. Aims. We simulate planet formation via pebble accretion up to crossover mass around stellar hosts with masses of 0.1-1.5 Msun, considering a range of formation locations, with and without Type I migration. Methods. We use a modified version…

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astro-ph.IMastro-ph.EPastro-ph.GAastro-ph.SR

The future of high-resolution UV spectroscopy: Science with a UV Échelle spectrograph on the Habitable Worlds Observatory, or a dedicated mission

Annalisa De Cia, David Cont, Kevin Heng, Boris Gänsicke, Frank Grupp, Ralf Bender, Helena Lamprecht, Frances H. Cashman et al.

High-resolution UV spectroscopy serves a diversity of science cases, from small bodies to planets, stars, and galaxies, but is currently limited to the Hubble Space Telescope and bright targets. Major advances require increasing sensitivity by at least one order of magnitude. Here we present the UV science cases for PEGASUS (Planets, Earths, Galaxies, And Stars UV Spectrograph), a UV Échelle high-resolution spectrograph concept, with $R = λ/δλ\sim 100\,000$ (full range 10 000-140 000) and coveri…

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astro-ph.SR

Chromospheric and Transition Region Responses of activities at the base of Coronal Plumes

Biswanath Malaker, Vishal Upendran, Durgesh Tripathi

We present the identification of the co-spatial and co-temporal small scale jets -- sometimes also named as jetlets -- at the base of the coronal hole plume associated with chromospheric and transition region (TR) flows. We identified 19 jets with coordinated observations recorded on March 19, 2016 using the Solar Dynamics Observatory (SDO) and the Interface Region Imaging Spectrograph (IRIS). Our analysis of \ion{Si}{4} 1393.7~Å line suggests blueshifts mostly in the range of 10 to 33~km~s$^{-1…

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astro-ph.HEastro-ph.IM

cuDART: a GPU-accelerated ray tracing code for generating synthetic observations of relativistic astrophysical sources

Henry Whitehead, Emma L. Elley, Christoper N. Everett

The generation of synthetic observations is required to compare simulations of astrophysical phenomena with real sources. We present a new open-source toolkit cuDART which allows meshed simulation data to be rapidly rendered into synthetic observations of optically thin emission, automatically accounting for a range of relativistic and geometric effects such as Doppler boosting. Unlike previous visualisation schemes which generally consider a single snapshot in time, cuDART is capable of account…

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astro-ph.EP

A Stellar-Type Dependence in the Rocky and Volatile Composition of Small Exoplanets

Ji Wang, Caroline Dorn, Komal Bali

We investigate the rocky and volatile composition of small exoplanets by modeling the population-level distribution of densities using a mixture framework that links interior structure models to observable quantities. We analyze three complementary samples spanning different stellar environments: the Luque \& Pallé M-dwarf sample, the DACE M-dwarf sample, and the DACE FGK sample. We consider a log-normal parameterization, which captures a characteristic core mass fraction (CMF) and the intrinsic…

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astro-ph.HEastro-ph.CO

Electromagnetic Emission and Orbital Evolution of Eccentric Supermassive Black Hole Binaries in Retrograde Disks

David ONeill, Mark J. Avara, Christopher Tiede, Daniel J. DOrazio, Zoltan Haiman, Andrew MacFadyen

Circumbinary disks around supermassive black hole binaries (SMBHBs) are expected to form across a broad range of inclinations, with retrograde configurations potentially a common occurrence. Here we present the first grid-based hydrodynamical simulations of retrograde circumbinary disks around eccentric SMBHBs, solving an energy equation that balances viscous and shock heating against blackbody radiative cooling. We investigate different initial disk Mach numbers $\mathcal{M}_a \in \{10, 20, 40\…

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astro-ph.HE

Free Neutron Decay in Kilonova Ejecta: X-ray/UV Flashes with Non-Thermal Effects

Daniel Brethauer, Daniel Kasen, Smaranika Banerjee, Raffaella Margutti, Ryan Chornock

Neutron star-bearing compact-object mergers can create a kilonova, a transient powered by the radioactive decay of material synthesized via rapid neutron capture ($r$-process). During the merger, a fraction of the ejecta is launched at high speeds ($\gtrsim$ 0.4c) that can lead to neutrons evading capture onto seed nuclei, resulting in free neutrons. The free neutrons then decay and inject additional energy that power early-time ($\lesssim$1 day) emission. Here, using \texttt{Sedona}, we present…

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astro-ph.COastro-ph.GAphysics.comp-ph

JZ-FMM: GPU-native differentiable N-body simulations with the Fast Multipole Method

Jens Stücker, Oskar Foldal

N-body simulations are an essential tool for modelling the evolution of gravitating systems. Differentiable N-body simulations allow solving complicated reconstruction problems by connecting observations of evolved systems to simple informative priors on their initial conditions. While so far most reconstruction efforts focus on mildly non-linear large scale dynamics, the internal dynamics of galaxies and clusters should exhibit rich information about their formation. The exploration of reconstr…

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astro-ph.GA

Little Dots: the ULX Analogy

Andrew King

I consider recent observations of the Little Dots (LDs) observed in high--redshift ($z\sim 7$) galaxies. I have suggested that the central black holes in these objects are probably fed mass at very super--Eddington (factors $\sim 50$) rates. In physical terms, this idea makes them supermassive analogues of the (stellar--mass) ultraluminous X--ray sources (ULXs), whose hard X--ray emission is strongly anisotropic (`beamed'). In this paper I argue that the recent discovery of extended rest--frame…

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astro-ph.GAastro-ph.CO

Exploring the AGN population in protoclusters: results from the TNG300 simulation and comparison with observations

A. Traina, F. Vito, A. Pillepich, A. Kapahtia, O. Cucciati, R. Gilli, F. Arrigoni-Battaia, C. Vignali et al.

In this work, we investigate the physical properties and cosmic evolution of galaxies and AGN in a sample of 280 protoclusters identified in the TNG300 simulation, selected to end up in $z = 0$ clusters with $M_{200, \rm c} > 10^{14} \, {\rm M_{\odot}}$. Our goal is to provide the first statistical view of AGN activity enhancement in a uniformly defined sample of overdense environments, and to identify the physical mechanisms driving it. We identify protoclusters as the progenitors of present-da…

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astro-ph.EPastro-ph.SR

The ALMA View of the Edge-on Gomez's Hamburger System: A Highly-Dynamic, Asymmetric Protoplanetary Disk Reveals the Earliest Phases of Giant Planet Formation

Charles J. Law, Jensen Lawrence, Richard Teague, Zhe-Yu Daniel Lin, Romane Le Gal, Kristina Monsch, Gordian Edenhofer, Hans Baehr et al.

Chemical tracers provide some of the strongest observational signatures of ongoing planet formation and localized dynamical perturbations in protoplanetary disks. In particular, sulfur-bearing molecules are predicted to be enhanced in regions of shock heating, ice sublimation, and gravitational instability. Here, we present high-angular-resolution ($\approx$0.$^{\prime\prime}$2) Atacama Large Millimeter/submillimeter Array observations of $^{12}$CO J=3-2, $^{13}$CO J=3-2, CS J=7-6, and SO J$_{\r…

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astro-ph.HE

Dispersion Measure Variability in Fast Radio Bursts from Photoionization

Brian D. Metzger

Magnetars became favored engines of fast radio bursts (FRBs) following the discovery of a luminous radio burst coincident with a hard X-ray flare from a Galactic magnetar. Several repeating FRB sources exhibit time-variable rotation measures and compact, spatially coincident persistent synchrotron radio emission, consistent with energetic-particle nebulae and confined by young supernova ejecta. Secular changes in the dispersion measure (DM) of repeating FRBs have also been observed, offering a c…

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astro-ph.HE

Dispersion Measure Variability in Fast Radio Bursts from Photoionization

Brian D. Metzger

Magnetars became favored engines of fast radio bursts (FRBs) following the discovery of a luminous radio burst coincident with a hard X-ray flare from a Galactic magnetar. Several repeating FRB sources exhibit time-variable rotation measures and compact, spatially coincident persistent radio emission, consistent with energetic-particle nebulae confined by young supernova ejecta. Secular changes in the dispersion measure (DM) of repeating FRBs have also been observed, offering a complementary pro…

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