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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.IM

Development of an adaptive optics testbed at MPIA for the ELT/Planetary Camera and Spectrograph (PCS)

Raphaël Pourcelot, Thomas Bertram, Peter Bizenberger, Markus Feldt, Markus Kasper, Silvia Scheithauer, Stefan Ströbele, Horst Steuer et al.

The Planetary Camera and Spectrograph (PCS) is a proposed second-generation instrument for the Extremely Large Telescope (ELT), dedicated to the direct imaging and characterization of exoplanets. To meet its demanding science requirements, PCS will incorporate an extreme adaptive optics (AO) system, building upon the heritage of existing ELT AO instruments such as ELT/METIS, as well as high-contrast AO systems at the ELT and the VLT, including SPHERE and its upcoming upgrade, SAXO+. PCS developm…

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astro-ph.HEastro-ph.SRnucl-th

Neutron star masses from electron-capture supernovae under equation-of-state uncertainties

Vishal Parmar, Domenico Scordino, Ignazio Bombaci

Electron-capture supernovae (ECSNe) are a promising formation channel for low-mass neutron stars, but the minimum gravitational mass of the neutron stars they produce depends on both the progenitor core structure and the neutron-star matter equation of state (EOS). We compute the electron-capture (EC) threshold gravitational mass ($M^\star_{WD}$) of cold white-dwarf-like O--Ne--Mg cores with representative compositions and map the baryon number onto cold neutron-star configurations constructed f…

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astro-ph.HEhep-th

Reconstructing the Auger UHECR Dipole: A Hybrid Analysis of 4LAC AGNs and Nearby Starburst Galaxies

Swaraj Pratim Sarmah, Umananda Dev Goswami, Sovan Chakraborty

The large-scale dipole anisotropy observed by the Pierre Auger Observatory above $8$~EeV provides important clues about the origin of ultra-high-energy cosmic rays (UHECRs). In this work, we investigate whether gamma-ray active galactic nuclei (AGNs) from the Fermi-LAT Fourth AGN Catalog (4LAC) can explain the observed dipole and examine the contribution of nearby starburst galaxies (SBGs). Incorporating source fluxes, redshift distributions, GZK attenuation, and a mixed-composition framework, w…

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astro-ph.IM

Effects of near-surface sedimentary structure on Newtonian noise for the Einstein Telescope: a 2-D numerical study

Shi Yao, Patrick Schillings, Johannes Erdmann, Andreas Rietbrock

Near-surface low-velocity sediments can strongly modify seismic wavefields and therefore affect estimates of Newtonian noise at underground gravitational-wave observatories. We investigate these effects using 2-D viscoelastic simulations of a sediment layer overlying hard-rock basement. Controlled experiments examine the influence of sediment-basement interface geometry, sediment shear-wave velocity, attenuation, and test-mass position. Relative to a homogeneous model, the sediment layer produce…

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astro-ph.IMastro-ph.HEcs.LGphysics.comp-ph

When a neural surrogate cannot accelerate a solver: runtime share, closed-loop drift, and the economics of uncertainty gating in a stiff coupled simulation

L. Thümmler, T. Kuroda

Learned surrogates for expensive inner solver blocks are a widely pursued route to faster multiphysics simulation. We report a controlled, end-to-end negative result and identify three structural barriers, none of them a deficiency of the network we trained. The testbed is the implicit Newton solve coupling energy-dependent neutrino radiation to matter in a general-relativistic radiation-hydrodynamics code, its most expensive physics routine per call. First, per-call cost and share of runtime ar…

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nucl-thastro-ph.HE

Signed Sound-Speed Deformations of BSk24-Anchored Barotropes: Neutron-Star Response

Ioannis Papathanasiou

Background: Localized structure in the equilibrium squared sound speed can affect neutron-star observables, but modifying $dP/dε$ requires thermodynamically consistent reconstruction and assessment over the complete declared domain. Purpose: We quantify the response to positive and negative localized sound-speed changes around a unified BSk24 baseline while keeping the deformation geometry, admission criteria, reconstruction, and fixed-mass comparison protocol fixed. Method: A Gaussian profile w…

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astro-ph.GA

The star formation history of NGC 2276: Comparison between SED modeling and hydrodynamical simulations

Luka Matijevic, Antonino Marasco, Neven Tomicic, Rory Smith, Peter Jonathan Watson, Alessandro Ignesti, Ian Roberts, Paul Sell et al.

Analyzing environmental effects in galaxy groups is pivotal for understanding how galaxies evolve in these moderate-density settings. The degree to which ram pressure versus tidal interactions drive the unusual morphologies and kinematics seen in group galaxies remains a subject of active debate. This study focuses on the nearby galaxy NGC 2276, which has the longest radio continuum tail in galactic groups. It is a member of the NGC 2300 group that possibly experiences both processes, and we aim…

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astro-ph.HE

Extensive Air Showers Parameters Estimation Using Machine Learning Techniques with Simulations of the FAST Telescope

Jiří Kvita, Monika Machalová, Radek Přívara, Rostislav Vodák, Jan Tomeček

We present the capabilities of the Fluorescence detector Array of Single-pixel Telescopes (FAST) observatory in the single telescope configuration as an important step towards the possible future large-field observatory for detecting ultra-high-energy cosmic rays. Reconstruction of main shower physics parameters are explored on noise-free simulated events using machine learning techniques in the challenging domain of a low-intensity transient signal. We find a very good correlation between the t…

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astro-ph.SR

Six new doubly eclipsing quadruples in a 2+2 architecture

P. Zasche, H. Kucakova, J. Kara, J. Merc, Z. Henzl, M. Masek, L. Cervinka, V. Dienstbier et al.

The study presents a confirmation of six quadruples with two sets of eclipses that have the 2+2 architecture. These so-called doubly eclipsing systems still present a quite rare group of stars. We collected all available photometric data and carried out a detailed analysis of them. In addition to the precise TESS photometry used to model the light curves for both inner eclipsing binaries, photometric survey data were also used, and more than 100 nights of our own dedicated observations were carr…

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astro-ph.EPastro-ph.IMmath.OC

Korean Space Collision Environment Assessment Framework Based on 3D-Cell Model

Jaewoo Kim, Minchan Song, Jinsung Lee, Jiwoong Yu, Hosik Kam, Jung Hyun Jo, Eun-Jung Choi, Jin Choi et al.

Space situational awareness (SSA) requires purpose-matched models across spatial, temporal, and fidelity scales. Building on our previously reported three-dimensional (3D) cell formulation and implementation, this study establishes a reproducible, resolution-aware, catalog-conditioned framework for macroscopic assessment of the low Earth orbit (LEO) collision environment. The framework maps supplied catalog or scenario populations to time-averaged spatial density and target-specific impact metri…

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astro-ph.GA

ASKAP discovery of a pair of large radio bubbles: on the origin of odd radio circles

Renzhi Su, Minfeng Gu, Hengxiao Guo, Neelesh Amrutha, Liang Cheng, Fangzheng Shi, Wenwen Zuo, Ruiyu Zhang et al.

We report the serendipitous discovery of a large, low-surface-brightness radio bubble in 944 MHz continuum data from the ASKAP Evolutionary Map of the Universe (EMU) survey. The structure, centred on the elliptical galaxy LEDA 217397 at a redshift of $z=0.040$, spans $\sim$8.4 arcmin, corresponding to a projected diameter of $\sim$399 kpc, and consists of two partly overlapping shells both with radii of $\sim$114 kpc. The integrated flux density of the bubble is $56.8\pm2.9$ mJy at 944 MHz, impl…

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cs.LGastro-ph.IMastro-ph.SRcs.CV

Neural Operator based Multi-Field Reconstruction of Inner Solar Boundary State

Vignesh Kumar Pandian Sathia, Reza Mansouri, Dustin J. Kempton, Pete Riley, Rafal A. Angryk

The Solar wind is a continuous flow of charged particles emanating from the solar surface and governed by complex, interacting magnetohydrodynamic processes. Accurate specification of inner-boundary conditions is essential for heliospheric modeling and solar-wind prediction. In many practical applications, only a subset of interacting multi-field variables is directly available, but for a comprehensive view of solar wind prediction and downstream magnetohydrodynamic simulations, a more complete…

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

Thermochemical constraints on a primordial-origin of gas-rich debris disks

H. Mitani, W. Ooyama, R. Nakatani, R. Kuiper, T. Hosokawa

Recent observations have revealed gas-rich debris disks around intermediate-mass stars at ages of tens of Myr. The origin of this gas remains unclear: it may be primordial, retained from the protoplanetary phase, or secondary, released from volatile-rich solids. Secondary-origin models reproduce CO emission but often overpredict neutral carbon. Recent observations and disk-evolution models suggest that primordial gas may survive longer than previously assumed, motivating thermochemical tests of…

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astro-ph.HE

A Two-month, Galaxy-targeted NIR Follow-up of the Sub-solar-mass Gravitational Wave Candidate S251112cm: Probing Electromagnetic Counterpart Scenarios

Gregory S. H. Paek, Felipe Olivares E., Willem B. Hoogendam

S251112cm is a nearby ($93 \pm 27$~Mpc) compact-binary merger candidate with a high inferred probability that at least one component is below $1\,M_\odot$. This event provides a rare test case for electromagnetic follow-up of a theoretically predicted but unconfirmed sub-solar-mass merger candidate. Motivated by scenarios predicting NIR-bright emission over weeks to months, we carried out a deep, galaxy-targeted UKIRT $J$-band campaign over approximately two months, prioritizing host candidates…

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astro-ph.HE

Timing, Polarization, and Single-Pulse Properties of Long-Period FAST Pulsars

Habtamu Menberu Tedila, Shijun Dang, Di Li, Pei Wang, Jianping Yuan, Rai Yuen, Na Wang, Shakhboz Khasanov et al.

We present phase-connected timing and polarization measurements for two long-period FAST-CRAFTS pulsars, PSRs J0000+6252 and J2131+3642, and extend single-pulse emission-state analysis to a five-source sample including PSRs J1903+1407, J1502+4653, and J2112+4058. FAST L-band timing baselines span 414 to 511 days; the two pulsars have spin periods of 1.11 to 1.55 s, period derivatives of $(3.99$ to $4.06)\times10^{-15}~{\rm s~s^{-1}}$, characteristic ages of 4.34 to 6.16 Myr, surface magnetic fie…

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astro-ph.HE

Tidal disruption of stellar binaries as a pathway to exotic transients

Mauricio González-Servín, Emilio Tejeda, Susana Lizano, Luis A. Manzaneda, Raúl Cano-Villegas

Tidal disruption event (TDE) progenitors are commonly modelled as single stars on parabolic orbits around a supermassive black hole (SMBH), yet observations point to a richer diversity of dynamical pathways. We show that the tidal separation of stellar binaries by a $10^6\,M_\odot$ SMBH provides a natural mechanism for producing eccentric TDEs. Using restricted three-body dynamics and smoothed particle hydrodynamics (SPH) simulations, we model a binary composed of a solar-like star (SLS) and a w…

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astro-ph.HE

Probing AU-Scale Magnetic-Field Reversals in the Interstellar Medium with Pulsar Scintillation

Jacob Yen, Daniel Baker, Dongzi Li, Ue-Li Pen

AU-scale structures in the interstellar medium have become relevant across several areas of astrophysics, from ISM microphysics to pulsar timing arrays and cosmic-ray (CR) propagation. Current sheets formed at magnetic-field reversals have drawn particular attention because they can deflect the dominant GeV CR population through large angles. Pulsar scintillation, an outstanding probe of plasma density, resolves these structures---but not their magnetic configuration. Conventional Faraday rotati…

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astro-ph.GA

Observational Evidence for the Kinematic Memory of Cosmic Filaments from Satellite Orbital Orientations

Peng Wang, Wei Wang, Wenting Wang, Min Bao, Xi Kang, Hong Guo, Youcai Zhang, Xiao-xiao Tang et al.

We present an observational study of the kinematic coherence between satellite orbital planes and the cosmic web. Using the SDSS DR12 galaxy sample combined with the Bisous filament catalogue, we investigate whether the orbital motion of satellites preserves the memory of filamentary accretion. For each satellite system, we define a projected orbital-normal vector using galaxy sky positions and line-of-sight velocity offsets. By measuring the angle $θ$ between this vector and the local projected…

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astro-ph.EP

On the formation of retrograde S-type planets in binaries with a polar circumbinary disk

Cheng Chen, Philip J. Armitage, C. J. Nixon, Stephen H. Lubow, Rebecca G. Martin

Retrograde S-type planets have been observed in several binary systems, yet their formation pathway remains poorly understood. With high-resolution hydrodynamic simulations, we demonstrate that a polar circumbinary disk around an eccentric, unequal-mass binary can form and sustain a retrograde mini disk around the primary star. This provides a direct in-situ formation channel for retrograde S-type planets. The mini disk forms via a sub-Keplerian accretion stream that is slightly misaligned from…

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astro-ph.SRphysics.space-ph

Where Do Periodic Density Structures Acquire Coherence? A Low-Coronal Resonator Candidate and a 12-Event STEREO/SECCHI Transfer Test

Olena Podladchikova

Periodic density structures (PDS) are trains of plasma enhancements carried into the heliosphere, but their repeated timing does not by itself identify where the cadence is set. We test whether PDS selected independently in the outer corona can be traced back to a low-coronal clock, and whether that organization survives through the EUVI--COR1--COR2 observing chain. We analyze 12 STEREO-A/SECCHI events on 2008 January 11--14 along a nonradial path. EUVI 171 A at 1.10--1.20 R_sun shows an unusual…

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astro-ph.SRphysics.space-ph

Where Do Periodic Density Structures Acquire Coherence? A Low-Coronal Resonator Candidate and a 12-Event STEREO/SECCHI Transfer Test

Olena Podladchikova

Periodic density structures (PDS) are trains of plasma enhancements carried into the heliosphere, but their repeated timing does not by itself identify where the cadence is set. We test whether PDS selected independently in the outer corona can be traced back to a low-coronal clock, and whether that organization survives through the EUVI--COR1--COR2 observing chain. We analyze 12 STEREO-A/SECCHI events on 2008 January 11--14 along a nonradial path. EUVI 171 A at 1.10--1.20 R_sun shows an unusual…

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astro-ph.EP

Exoplanet System Architecture: Sculpting the Inner Regions

Mark R. Swain, Geoffrey Bryden, Jonathan C. Tan, Eric Gaidos, George Zhou, Caeley V. Pittman, Christopher M. Johns-Krull, Ann Marie Cody et al.

In this study, we seek to improve our understanding of the competing roles of disk-driven and planet-planet dynamical migration in sculpting planetary system architecture in the inner $\lesssim 1.5$ au of protoplanetary disks. Over a range of host star masses, we compare the orbit semimajor axis values of transiting multi-planet and resonant systems to observationally-derived estimates of protoplanetary disk inner truncation radius $R_{i}$, corotation radius $R_{co}$, and dust sublimation radius…

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cs.LGastro-ph.IM

What AstroPT knows about galaxies, and what that can teach us about LLMs

UniverseTBD, :, Kshitij Duraphe, Aman Kumar, Michael J. Smith, Shashwat Sourav

Interpretability research increasingly asks when concepts emerge during training and whether linear probes recover real structure, but in language models these claims are hard to validate because language offers little ground-truth ordering of concepts or relationships among them. We propose the use of astronomical ground truth through AstroPT, a transformer trained on millions of galaxy images, as a calibration testbed. AstroPT is an LLM-like model trained within a domain where the difficulty o…

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astro-ph.EP

Spin-Orbit Alignment of Two Neptune-size Planets Younger than 500 Myr: TOI-560 b and TOI-5082 b

Elina Y. Zhang, Fei Dai, Andrew W. Howard, Samuel P. Halverson, Howard Isaacson, Ryan A. Rubenzahl, Huan-Yu Teng, Xian-Yu Wang et al.

Stellar obliquity measurements provide a direct probe of planetary system dynamics, but remain sparse for Neptune-size planets, particularly at young ages. We present Rossiter-McLaughlin measurements for two young Neptune-size planets, TOI-560 b and TOI-5082 b, using time-resolved Keck Planet Finder (KPF) spectroscopy and joint modeling with TESS transit photometry. We measure sky-projected obliquities of $λ_b = -25 \pm 16^\circ$ for TOI-560 b and $λ_b = 19^{+17}_{-13}{}^\circ$ for TOI-5082 b. C…

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astro-ph.SR

On the formation of subdwarf B stars via engulfment of substellar companions

Antoine Thuillier, Lionel Siess, Valérie Van Grootel

The canonical scenario for the formation of subdwarf B (sdB) stars involves the ejection of the progenitor's envelope near the tip of the Red Giant Branch (RGB), concurrent with the onset of core He-burning. While binary interactions are known to dominate sdB formation, the origin of apparently single sdB stars remains uncertain. We investigate the conditions under which a sdB progenitor can eject its envelope through the engulfment of a substellar companion, using an energy balance approach. We…

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astro-ph.SR

A superflare of BP Tau simultaneously caught by EP X-ray and TESS optical observations

Xingyu Zhou, Mingjun Liu, Gregory J. Herczeg, P. Christian Schneider, Fabio Favata, Chenwei Yang, Chichuan Jin, Dongyue Li et al.

Multiwavelength observations of stellar flares trace the activity of different components of the stars' outer atmosphere, providing insight into their interactions. In the present paper, we report a superflare from BP Tau, simultaneously observed with the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) satellite and TESS. While we attribute the X-ray flux increase to a magnetically powered flare, the optical light curve likely results from the superposition of the flare and an…

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astro-ph.IM

Instrumental artifacts in photonic lantern spectroastrometry and their mitigation with PLred

Yoo Jung Kim, Michael P. Fitzgerald, Malena Bloom, Aidan Walk, Sebastien Vievard, Miles Lucas, Olivier Guyon, Sylvestre Lacour et al.

Spectroastrometry is a powerful spectral-differential technique for probing angular scales below the resolution limit, but it is also well known to be susceptible to instrumental artifacts that can mimic or obscure real signals. In photonic lantern spectroastrometry, recently demonstrated on-sky with Subaru/FIRST-PL, the astrometric signal is encoded in relative flux variations between lantern outputs rather than in centroid shifts along a slit. This changes the artifact landscape: some slit-bas…

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astro-ph.GA

The Mass-Size Plane Does Not Resolve the Identifiability Limit of the Radial Acceleration Relation

Lukas A. Sosna

We present a computational audit of the identifiability limits for structural corrections to the Radial Acceleration Relation (RAR) using a canonical subset of the SPARC database (N = 126). Rather than proposing a new dynamical law, we establish the observational conditions under which such a law would be mathematically recoverable. We resolve three methodological controls that heavily influence RAR interpretations. First, we isolate a -0.39 dex residual offset between the eight galaxies in the…

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gr-qcastro-ph.IM

Correlated and coincident noise in Einstein Telescope's triangular configuration

Jan Harms

The Einstein Telescope (ET) is a proposed underground infrastructure in Europe to host future generations of gravitational-wave (GW) detectors. Two configurations are under investigation. The first is the two-site solution with an L-shape detector at each site similar to the LIGO configuration. The second configuration is the single-site triangular detector. While numerous analyses over the last decade have already proven that the distributed network of GW detectors is the scientifically preferr…

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astro-ph.HE

Galactic Microquasar and Supernova Remnants Imprinting on Diffuse Neutrino and Gamma-Ray Sky

Shiqi Yu, Bing Theodore Zhang

Recent detections of Galactic diffuse neutrinos by IceCube and $γ$-rays by LHAASO offer direct probes into the origin of Galactic cosmic rays. Conventional diffuse templates typically assume a single cosmic-ray injection spectrum across a wide energy range, without accounting for independent contributions from distinct accelerator populations. Here, we present a numerical framework that models Galactic diffuse neutrino and $γ$-ray emission that incorporates contributions from both microquasar an…

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