研究動向

astro-ph.EPastro-ph.IM2026年9月7日

The First Observations of Moonlit Satellites

Sarah E. Caddy, Stephen E. Catsamas, Michele Trenti, Lee R. Spitler, Patrick North

Optical Space Domain Awareness (SDA) operations have traditionally relied on Sunlit passes near the terminator, limiting continuous tracking of low-Earth orbit (LEO) satellites. In this work, we show that by accounting for all four major illumination sources: Sunlight, Earthshine, Moonlight, and Lunar-Earthshine, large LEO satellites like the ISS can be optically monitored for a full 24 hour period. We present what we believe to be the first quantitative observations of the International Space S…

詳細を見る →

astro-ph.GAastro-ph.CO2026年9月7日

Recovering the characteristic halo mass of rare populations from clustering: a benchmark using the Millennium Simulation

Amrita Banerjee, Darren Croton

We measure how accurately the characteristic halo mass of a rare, massive population can be recovered from clustering alone, using dark matter haloes in the Millennium simulation, where the true masses are known. Massive samples of 25 to 10000 haloes are cross-correlated against field reference samples of 5000 to 50000 haloes at six redshifts over $0 \leq z \leq 5.29$. The bias is measured at $r = 8\,h^{-1}\,\mathrm{Mpc}$ and inverted to return a characteristic mass, which we compare with the me…

詳細を見る →

astro-ph.GA2026年9月7日

Between Little Red Dots and Star-Forming Galaxies: A Sequence in the Optical Continuum Slope

Kristiphong Boonmee, Akio K. Inoue, Masafusa Onoue, Xingyao Cai

The "Little Red Dots" (LRDs) uncovered by JWST are typically analyzed as a distinct class of objects; however, whether they are separated from ordinary star-forming galaxies by a genuine boundary has not been tested at the population level. Using a sample of $\sim3,500$ galaxies at $3 \lesssim z \lesssim 8$ with NIRSpec/PRISM spectra from the DAWN JWST Archive, we modeled their rest-frame UV-to-optical continuum emission with power laws and located the sources in the $β_{\rm{UV}}$-$β_{\rm{opt}}$…

詳細を見る →

astro-ph.IM2026年9月7日

An adaptive parameter optimization method for astronomical image alignment using Bayesian optimization. I. A hierarchical search strategy for FWHM and SNR

Yongjie Zhang, Yigong Zhang, Zhenjun Zhang, Xiangming Cheng, Lei Xiong, Xiaoguang Yu, Jie Su, Jiancheng Wang et al.

The alignment and stacking of astronomical images are fundamental steps for detecting faint objects and performing high?precision astrometry. In traditional alignment workflows, the extraction of source lists is critically dependent on key parameters such as the Full Width at Half Maximum (FWHM) and the Signal-to-Noise Ratio (SNR) threshold. These parameters are often selected manually through an inefficient trial-error process that lacks objectivity and does not guarantee optimal results. We pr…

詳細を見る →

astro-ph.IMastro-ph.SR2026年9月7日

Filter and baffle design for the short-wavelength camera on SOLAR-C EUVST

James McKevitt, Duncan Rust, Berend Winter, David Walton, Sarah Matthews, Ted Pyne, Yukio Katsukawa, Ryohko Ishikawa et al.

SOLAR-C, which is scheduled to launch in the late 2020s with the Extreme Ultraviolet High-Throughput Spectroscopic Telescope (EUVST), will deliver EUV spectroscopy of the solar atmosphere with unprecedented temperature coverage and resolution. We present the optical design and mechanical impacts for the short-wavelength camera, and how our design choices affect scientific performance using complete forward modelling. We discuss the design and optical impact of the thin-film aluminium filter and…

詳細を見る →

astro-ph.HEastro-ph.CO2026年9月7日

NEXUS: Transient Searches and First Results from Year One Observations

Ming-Yang Zhuang, Lei Hu, Justin D. R. Pierel, Zhiwei Pan, Yue Shen, Adam J. Burgasser, Xiaohui Fan, Luis C. Ho et al.

We describe ongoing efforts of high-redshift transient searches using multi-epoch NIRCam imaging (F200W+F444W) and NIRSpec MSA/PRISM spectroscopy from the NEXUS JWST multi-cycle Treasury program targeting the north ecliptic pole region. The transient search area covers $\sim 61.5\,{\rm arcmin^2}$ between the reference epoch and each subsequent NEXUS-Deep epoch at a cadence of $\sim2$~months. In the first year of observations from NEXUS, we detect 68 robust transients, with the host photometric r…

詳細を見る →

gr-qcastro-ph.HEhep-th2026年9月7日

A New Window for Testing the PPN in the Strong-Field Regime: Stellar Rotation of S301

Mohsen Khodadi, Salvatore Capozziello

The recently discovered S301 star, with an orbital period of 8.7 years and eccentricity $e = 0.982$, reaches a pericenter of just $140\,R_{\mathrm{s}}$ --- approximately nine times closer than S2's $\sim 1200R_{\mathrm{s}}$ --- offering an unprecedented laboratory for testing strong-field gravity. We demonstrate that S301's stellar spin precession provides a novel probe of the PPN parameter $γ$, scaling as $(2γ_{\mathrm{PPN}} + 1)/3$ relative to general relativity (GR). For maximum projected vel…

詳細を見る →

astro-ph.GAastro-ph.SR2026年9月7日

Catching Up with the Fastest Star in the Galaxy: A Two-Passage GRAVITY+ Campaign to Detect S301's Schwarzschild Precession

Joseph Catanzarite

S301 is the fastest known star in the Galaxy. It orbits Sgr A* every 8.68 yr on an e = 0.9832 orbit that carries it within 136 Schwarzschild radii at 25,600 km/s (GRAVITY Collaboration 2026). An orbit like that must precess, by the same Schwarzschild effect that turns Mercury's perihelion, whatever the spin of the black hole. We ask whether an astrometry-only GRAVITY+ campaign covering the 2031.8 and 2040.5 periapsis passages can catch it. We validate a relativistic light-curve model, design a 1…

詳細を見る →

astro-ph.COastro-ph.GA2026年9月7日

Little Red Dot Cosmology: A Matter-Era Baryon Acoustic Oscillations Probe of $Λ$CDM

Jessica A. Zebrowski, Rohan P. Naidu

The discovery of Little Red Dots (LRDs) with JWST provides a new source population for cosmology in a largely unmapped period of cosmic history. LRDs are most numerous at $4\lesssim z\lesssim9$, thereby bridging existing low-redshift large-scale-structure measurements and the cosmic microwave background. In this epoch, the Universe is deep in the matter-dominated era, where dark energy is dynamically negligible and the expansion history is tightly predicted in $Λ$CDM, making these redshifts a cl…

詳細を見る →

astro-ph.GA2026年9月7日

A Unified Magnetohydrodynamic Scaling Relation for the Multiphase Interstellar Medium

Mengke Zhao, Guang-Xing Li, Keping Qiu

The interplay of magnetic fields, turbulence, and gravity governs the structural evolution of the interstellar medium (ISM) and the initial conditions of star formation, yet observational gaps have long enforced a broken power-law description of the magnetic field--density relation. Here we assemble a unified dataset spanning ten orders of magnitude in density ($10^{-26}$--$10^{-16}\,\mathrm{g\,cm^{-3}}$) by combining pulsar and Zeeman observations. The unified data are consistent with a continu…

詳細を見る →

astro-ph.EP2026年9月7日

Constraining the orbit of the retrograde planet in the $ν$ Octantis system

Alan Cefali Signor, Alexandre C. M. Correia, Maria Helena Moreira Morais, Timothée Vaillant, Ho Wan Cheng, Man Hoi Lee, Trifon Trifonov

The $ν$ Octantis system is composed of a compact stellar binary and a retrograde S-type planet orbiting near the edge of stability. Here, we investigate the dynamically viable architectures of this system by exploring the planetary orbital elements with a Monte Carlo method. To handle the large number of free parameters, we employed a novel approach in which all relevant orbital parameters were varied simultaneously, which we refer to as corner stability maps. Furthermore, since the osculating o…

詳細を見る →

astro-ph.EPastro-ph.SR2026年9月7日

The Effect of X-Ray and Accretion Variability on Mid-Infrared Lines in the Young Disk-Bearing Binary DQ Tau

Bayron Portilla-Revelo, Konstantin V. Getman, Ágnes Kóspál, Dmitry Semenov, Vitaly Akimkin, Lis Zwicky, Jan Forbrich, Sierk van Terwisga et al.

A star's radiation field is the main energy source of a planet-forming disk. Stellar photons---from X-rays to optical---are reprocessed in the inner protoplanetary disk enabling mid-IR diagnostics of the disk's physical conditions. Most pre-main-sequence stars accrete at moderate rates and emit X-rays efficiently. Such activity is expected to drive stochastic variability in the stellar spectrum. It is not clear to what extent such variability affects the thermochemical structure of protoplanetar…

詳細を見る →

astro-ph.IMastro-ph.HEastro-ph.SR2026年9月7日

Multimessenger Spectroscopy

Kristen Lackeos

A multimessenger method is developed for scheduling optical spectroscopy of ultracompact double white dwarf binaries from Laser Interferometer Space Antenna (LISA) data. The orbital parameters inferred from the gravitational wave (GW) signal are used to predict the argument of latitude $u(t)$, which sets the phase dependence of the radial velocity. With $u(t)$ known in advance, spectra can be taken at selected orbital phases. The GW and spectroscopic descriptions are linked by $u(t)=Φ_{\rm GW}(t…

詳細を見る →

physics.space-ph2026年9月7日

AETHER-P3 Nowcast v1.0: Model Description, Training-Data Construction, and Validation Technical report prepared in support of CCMC onboarding

Ruochen Wang, Xiaoli Bai

AETHER-P\textsuperscript{3} Nowcast v1.0 is a machine-learning-based global thermospheric neutral-density model developed for low-Earth-orbit applications and prepared for onboarding to NASA's Community Coordinated Modeling Center (CCMC). The model provides pointwise neutral-density estimates together with predictive uncertainty using a deep evidential regression framework driven by causal solar, solar-wind, geomagnetic, spatial, temporal, and empirical-model inputs. This report documents the re…

詳細を見る →

astro-ph.IMcs.CV2026年9月7日

NEO-BENCH: A New Multi-Source Benchmark for Generalizable Astronomical Streak Detection

Jiayou He, Jessica Yao

Near-Earth Objects (NEOs) can appear as faint streaks in long-exposure astronomical images. Detecting these streaks across diverse observatories requires methods that remain reliable despite differences in image quality, orientation, sky background, and noise. However, existing detectors are commonly evaluated using data from only one source, providing limited evidence of cross-source generalization. We introduce NEO-Bench, a multi-source benchmark containing 8,376 images from five astronomical-…

詳細を見る →

astro-ph.SRastro-ph.GA2026年9月7日

Elusive helium stars in the gap between subdwarfs and Wolf-Rayet stars III. Formation of the Galactic population of stripped helium stars

L. R. Yungelson, A. G. Kuranov, A. V. Mishakina

Population synthesis based on the grid of pre-computed evolutionary sequences for close binaries is applied to the problem of formation of the Galactic population of stripped helium stars, the remnants of $5 \lessapprox M/M_\odot \lessapprox 24$ primary components of close binaries after RLOF. Stellar rotation is taken into account. For the current star formation rate in the Galaxy $2\,M_\odot yr^{-1}$, the estimate of the number of 1 to $7\,M_\odot$ objects with $T_{eff} \gtrapprox $25000K rang…

詳細を見る →

astro-ph.GAcond-mat.quant-gasgr-qc2026年9月7日

Fractional Bose-Einstein Condensate Dark Matter Cores: Numerical GPP Solutions and SPARC Rotation Curves

Akila Labadi, Mohamed Benarous, Ahmed Hocine

We investigate a fractional Bose Einstein condensate dark matter scenario in which an ultralight bosonic component forms a self gravitating core embedded in a predominantly cold dark matter halo. The stationary GPP system solved numerically beyond the TF approximation leads to energetically bound equilibrium configurations and good phenomenological fits to the selected rotation curves from 30 SPARC galaxies.

詳細を見る →

hep-phastro-ph.HEhep-th2026年9月7日

Solar Capture Tests of Inelastic Dark Matter after the LZ High-Recoil Event

Mattia Di Mauro, Halim Shaikh

The LUX-ZEPLIN (LZ) Collaboration has reported a $248$ keV nuclear-recoil candidate for which endothermic dark matter (DM) gives some of the largest local significances. We study Solar-capture constraints on three simple interpretations: a thermal Higgsino, a thermal pseudo-Dirac fermion with off-diagonal vector interactions, and neutron-philic endothermic spin-dependent scattering through $\mathcal{O}_4$. The canonical full-density thermal Higgsino is excluded: its LZ-preferred splitting near $…

詳細を見る →

astro-ph.EPastro-ph.GAastro-ph.IM2026年9月7日

Calibration of CNEOS Fireball Velocities and the Robustness of Nominally Hyperbolic Events

Volkan Duran, Abraham Loeb

The NASA/JPL CNEOS Fireball Data catalogue provides a near-global record of bright atmospheric entries but does not report per-event velocity covariance. We calibrate its kinematic accuracy using 19 events with independent reference trajectories and use optical, satellite, radar, and infrasound catalogues as source-specific controls. For nine modern high-quality comparisons, the CNEOS-minus-reference speed residual has mean -1.00 km s$^{-1}$ and standard deviation 0.86 km s$^{-1}$; variance deco…

詳細を見る →

gr-qcastro-ph.HE2026年9月7日

Physics-based phenomenological modeling of binary black hole hierarchical formation 2: Autodifferentiable functional inference of hierarchical compact-binary populations

R. O'Shaughnessy, M. Zeeshan, M. Qazalbash

The gravitational-wave (GW) census contains mass and spin structure consistent with contributions from black holes assembled through repeated mergers in dense environments. Connecting that structure to formation physics requires models that are both physically interpretable and tractable within population inference. We construct an autodifferentiable, physics-based phenomenological model in which each dense environment is represented by a coagulation response and a population of such environment…

詳細を見る →

astro-ph.IM2026年9月7日

Chromatic Anisoplanatism in Adaptive Optics: A detailed comparison of theory with numerical simulations

B. Femenía-Castellá, N. Devaney

Context. Chromatic Anisoplanatism arises in Adaptive Optics because atmospheric refraction makes rays of different wavelengths follow different paths through the atmosphere resulting in different wavefronts at the sensing wavelength and the science wavelength, introducing a correction error that grows rapidly with zenith distance. Aims. Using numerical simulations based purely on geometric optical propagation we aim to validate the theoretical framework describing wavefront errors caused by Chro…

詳細を見る →

astro-ph.EP2026年9月7日

An Outer Giant Excites and Constrains the Orbit of $π$ Mensae d

Qunfeng Jiang

The nearby $π$ Mensae system contains the eccentric giant planet b on a 5.7 yr orbit, the 6.27 day transiting sub-Neptune c, and a candidate planet d on a 123 day orbit between them. Published estimates place the eccentricity of d between approximately 0.2 and 0.4. We reanalyze 772 published velocities with three-Keplerian fits and explore three-dimensional b-d dynamics with N-body integrations. The high-eccentricity solution persists when the phase or apsidal prior is widened; exact importance…

詳細を見る →

astro-ph.GAastro-ph.CO2026年9月7日

ADF22-WEB: Massive galaxy formation shaped by cosmic web filaments in the z = 3.1 proto-cluster core

Hideki Umehata, Ian Smail, Charles C. Steidel, Bret D. Lehmer, Kouichiro Nakanishi, Bunyo Hatsukade, Mariko Kubo, Norika Okauchi et al.

We present a census of dust, molecular gas, and galaxy structure in 18 dusty star-forming galaxies (DSFGs) at $z=3.09$ embedded in Ly$α$-traced cosmic web filaments in the core of the SSA22 proto-cluster, using multi-band ALMA, JWST imaging, and JVLA CO(1--0). Using up to six ALMA bands and Herschel/SPIRE data, we construct rest-frame far-infrared spectral energy distributions. The DSFGs span two orders of magnitude in far-infrared luminosity ($L_{\rm FIR}\sim10^{11}$--$10^{13}L_\odot$), with me…

詳細を見る →

astro-ph.SRastro-ph.IM2026年9月7日

PySeshat: A Validated Python Pipeline for Binary-Star Orbit Determination and Al-Wardat Stellar Atmosphere Modeling

R. I. El-Kholy, Z. M. Hayman

Precise stellar masses and physical parameters for binary and multiple star systems require, respectively, well-constrained orbital solutions and independent stellar-atmosphere modeling. Existing open-source software addresses these separately, and hierarchical triple systems additionally require simultaneous fitting of their inner and outer orbits, a treatment few existing tools provide. We present PySeshat, an open-source Python package unifying binary and hierarchical-triple orbit determinati…

詳細を見る →

astro-ph.HE2026年9月6日

Possible Sources of Iron Nuclei in Ultra-High-Energy Cosmic Rays

Anna Uryson

The origin of a cosmic ray particle with an ultra-high energy of 2.44 x 10^20 eV recorded by the Telescope Array is discussed by assuming that it is a heavy nucleus, namely an iron or silicon nucleus. Iron is chosen as a heaviest element in cosmic rays, while silicon is chosen to find out how much the theoretical results obtained vary with the mass of the heavy nucleus. Assuming extragalactic origin of the particle with such energy, the constraints on the distances to possible sources are analys…

詳細を見る →

astro-ph.HEgr-qc2026年9月6日

CoportSL: A Contribution-constrained Hybrid Slow-light Framework for Time-dependent Polarized GRMHD Imaging

Fan Zhou, Jiewei Huang, Yuehang Li, Minyong Guo, Bin Chen

Fast-light approximations neglect fluid evolution along rays, whereas slow-light modeling is indispensable for recovering the true magnetohydrodynamic state. However, full slow-light radiative transfer for extended general relativistic magnetohydrodynamic (GRMHD) sources requires simultaneous access to many fluid snapshots and is memory-intensive. We introduce CoportSL, the first contribution-constrained hybrid slow-light framework for time-dependent full-Stokes imaging. It uses emission, absorp…

詳細を見る →

astro-ph.HEastro-ph.GA2026年9月6日

Chandra X-ray imaging and IC/CMB model for the inner jet of PKS 0637-752

Jaya Maithil, Daniel A. Schwartz, Aneta Siemiginowska, Diana M. Worrall, Preeti Kharb

We present the X-ray surface brightness maps of the jet from the quasar PKS 0637-752, using two epochs of archival Chandra observations (1999 and 2017). We present, for the first time, a model of the faint inner jet extending from 3.4 to 7 arcsec from the core, interpreting its X-ray emission as inverse Compton scattering of cosmic microwave background photons by the synchrotron-emitting relativistic electrons. The inner jet contrasts with the bright outer part of the jet, dominated by several d…

詳細を見る →

astro-ph.SR2026年9月6日

Stage-dependent superhump waveform evolution and non-stationary positive-superhump timing in the near-period-gap dwarf nova YZ Cancri

Zhibin Dai, Xuefei Chen, Zhanwen Han

We present a photometric and timing study of the near-period-gap SU~UMa-type dwarf nova YZ~Cancri, based on nearly continuous Transiting Exoplanet Survey Satellite (TESS) photometry and long-baseline ground-based observations. Our main observational result is that the positive-superhump (SH) waveform follows a repeatable, stage-dependent sequence during superoutbursts (SOs). In the two well-covered TESS SOs, and consistently in the long-baseline ground-based SO sample, the plateau waveform evolv…

詳細を見る →

astro-ph.IM2026年9月6日

Generating radio continuum survey maps of arbitrary size with latent diffusion models

Tobias Vičánek Martínez, Marcus Brüggen

Radio surveys provide exponentially increasing amounts of observational data, which requires the development of novel data reduction and analysis methods. To this end, realistic simulations of observational data provide controlled environments for testing and developing new methods. Diffusion models excel at synthesizing realistic image data, but are limited by size constraints and high computational demands. We implemented a latent diffusion model (LDM) to synthesize realistic radio survey map…

詳細を見る →

astro-ph.IMastro-ph.EPphysics.opticsphysics.space-ph2026年9月6日

Mechanisms of Electrostatic Charge Formation and Retention in Lunar Regolith

Minhyeok Kim, Hyun Jung Kim, Sang H. Choi, Ashley Daeun Jung

As the Artemis program advances toward the lunar south pole and permanently shadowed regions (PSRs), understanding lunar charging is increasingly important for protecting astronauts, robotic systems, instruments, and infrastructure. Persistent darkness, cryogenic temperatures, low regolith conductivity, and long charge-relaxation times may allow energetic-particle-induced charge to accumulate beneath the surface. This Technical Memorandum addresses a key unresolved question: how is electrostatic…

詳細を見る →