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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.HEastro-ph.COastro-ph.GA

A binary black hole merger rate comparison within the same metallicity - star formation rate framework

Lumen Boco, Michele Bosi, Cecilia Sgalletta, Amedeo Romagnolo, Michela Mapelli

Recent studies have suggested that binary population synthesis models, when coupled with observationally based, metallicity-dependent star formation rate density, overpredict the observed local binary black hole (BBH) merger rate density. The significance of this tension might vary depending on the specific code and parameters adopted. Thus, a more extensive exploration of the parameter space is required. In this work, we perform such an extended analysis by considering BBH merger efficiencies c…

hep-thastro-ph.HEgr-qc

Quasinormal modes as exterior probes of black hole interiors in our Universe

Sašo Grozdanov, Vita Movrin, Samuel Valach

We consider a scenario in which a black hole is enclosed in a reflecting timelike cavity and linearly perturbed. For the resulting quasinormal spectra of gravitational, electromagnetic, and other perturbations, in conjunction with our arXiv:2606.11297, we establish a thermal product formula and derive a universal asymptotic expression for high quasinormal overtones. Both results hold in asymptotically flat, de Sitter, and Anti-de Sitter spacetimes (known previously). This spectral signature dire…

astro-ph.HEgr-qc

Explosions from Rotating Very Massive Star Collapses to Black Holes: Effects of Nuclear Burning

Sho Fujibayashi, Alan Tsz-Lok Lam, Yuichiro Sekiguchi, Masaru Shibata

We investigate the collapse of rotating very massive and supermassive stellar cores using numerical relativity simulations including an alpha-chain nuclear reaction network and neutrino cooling. Our main survey focuses on newly constructed models with initial core masses of $2 \times {10}^{3}-5\times 10^4M_\odot$. The collapse is triggered either by pair instability in lower-mass cores or by general-relativistic instability in higher-mass cores. We find that higher-mass cores undergo a nearly ho…

astro-ph.EP

Effects of Pebble Accretion Isolation Mass on Observable Exoplanet Properties

Lucas Brefka, Rebekah I. Dawson, Mariah G. MacDonald, Phoebe Sandhaus, Eric B. Ford

The Kepler Mission has discovered a plethora of planetary systems with super-Earth sized planets. These systems exhibit many properties, from widely-spaced planets with non-negligible eccentricities and inclinations, to tightly-spaced, coplanar, and nearly circular multi-planet systems. The observable properties of these systems, such as planet-planet spacings, multiplicity and orbital morphology, can be strongly influenced by the initial conditions of formation. These conditions affect the earl…

astro-ph.GAastro-ph.HE

Orbital Migration of Interacting Stellar Mass Black Holes in Disks around Supermassive Black Holes. III. Mass Distribution of Hierarchical Mergers

Katherine L. Gonglewski, Amy Secunda, Mordecai-Mark Mac Low, K. E. Saavik Ford, Barry McKernan, Fabian R. N. Schneider

Active galactic nucleus (AGN) disks are a promising location for the formation of binary black holes (BBHs) that will merge on relatively short timescales and be detected by LIGO-Virgo-KAGRA (LVK). To compare the mass function (MF) of black holes (BHs) undergoing hierarchical mergers in AGN disks to the inferred MFs from LVK observations, we perform 360 simulations with an N-body code augmented to include an analytic model for migration torques and other gas forces. We focus on the region surrou…

astro-ph.IMastro-ph.HE

Laser Metrology for Precision Alignment of Transmission Gratings in the REDSoX Soft X-ray Polarimeter

Swati Ravi, Alan Garner, Jill Juneau, F. Elio Angile, Ralf K. Heilmann, Herman L. Marshall, Sarah N. T. Heine

The Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX) is a NASA sounding-rocket mission designed to perform the first astrophysical spectropolarimetry in the 0.2-0.4 keV energy band. The instrument uses critical-angle transmission (CAT) gratings to disperse incident X-rays onto laterally graded multilayer (LGML) mirrors, requiring 48 individual gratings to be co-aligned to within 6 arcminutes in yaw, pitch, and roll. To support the systematic assembly of the grating array, we…

astro-ph.EPastro-ph.SR

The sensitivity of TESS to transiting planets in TOIs with close-in stellar companions

Colin Littlefield, Kathryn V. Lester, David R. Ciardi, Steve B. Howell

High resolution imaging with optical speckle interferometry has revealed that many transiting exoplanet host stars possess close-in stellar companions. The objective of this study is to quantify how the presence of these companions impacts the ability of TESS to detect the transits of small planets. We accomplish this by examining 2052 TESS Objects of Interest (TOIs) that appear to be single-star systems based on speckle interferometric observations as well as 188 TOIs in unresolved ($< 1.2\arcs…

astro-ph.IM

Numerical Model Simulation of the Carruthers GCI Images

Heather Filippini, Alex Zhang, Evan Widloski, Jason McPhate, Lara Waldrop, Thomas Immel, John Clarke, Pratik Joshi et al.

The Carruthers Geocorona Observatory, launched in September 2025, is NASA's first mission devoted to investigating the fundamental nature of Earth's exosphere from its distant vantage in halo orbit around the Earth-Sun Lagrange (L1) point. Its primary payload, the GeoCoronal Imager, consists of two coaligned photometric imagers that measure the radiance of ultraviolet emission at 121.6 nm (Lyman-$α$, or Ly-$α$) from exospheric hydrogen atoms simultaneously at wide and narrow fields of view. In o…

astro-ph.EP

No Helium Detected in LHS 1140 b from Four JWST NIRISS/SOSS Transits

Katherine A. Bennett, Carlos Gascón, Jacob Lustig-Yaeger, Guangwei Fu, David K. Sing, Kevin B. Stevenson, Jonathan Brande, Munazza K. Alam et al.

In the effort to determine which low-mass exoplanets have atmospheres, LHS 1140 b remains one of the most favorable targets. Its large size (5.6 $\rm M_{\oplus}$ and 1.7 $\rm R_{\oplus}$) and relatively long orbital period (24.7 days) imply an atmosphere may be likely, and notably, recent interior models favor either a hydrogen-dominated "mini-Neptune" or a "water world" over a true terrestrial planet. Another possibility is that it has a helium-rich atmosphere. This hypothesis is supported by r…

astro-ph.EP

Strict Limits on Helium Absorption from LHS 1140 b from Four JWST NIRISS Transits

Michael Radica

Orbiting in the habitable zone of its host star, the 1.7 $R_\oplus$, 5.6 $M_\oplus$ planet LHS 1140 b is a target of great interest. Recently Cherubim et al. (2026) published a detection of metastable He escaping from the atmosphere of LHS 1140 b, simultaneously providing the first concrete inference of an atmosphere on this planet and indicating that the atmosphere is He-rich and H-poor as would be expected due to Gyrs of fractionated mass loss. In this work, we analyze four archival transits o…

astro-ph.IM

JWST MIRI Medium Resolution Spectrometer Point Fixed Pattern Corrections: Cleaner and Higher Signal-to-Noise Spectra of Point Sources

Karl D. Gordon, David R. Law

The JWST Mid-Infrared Instrument Medium Resolution Spectrometer provides the capability to obtain spectra from 5-28 micron. The JWST data reduction pipeline removes the majority but not all of the instrument artifacts and the signal-to-noise (S/N) of the resulting spectra are limited by fixed pattern noise. Building on previous work, Point Fixed Pattern Corrections (PFPCs) are constructed using observations of O, A, and G dwarf flux calibration stars and asteroids taken using the default four po…

astro-ph.SRastro-ph.HEnucl-thphysics.plasm-ph

The Production of Electron-Capture Elements in Thermonuclear Supernovae: Theory vs. Observations

S. Shiber, P. Hoeflich, T. Mera, E. Fereidouni, Z. Levy, D. Maci, C. Ashall, K. Medler et al.

Type Ia supernovae (SNe Ia) explosively destroy carbon-oxygen white dwarfs (WDs) in multiple stellar systems. They produce approximately 50% of the iron-group elements in the Universe, synthesize electron-capture (EC) elements, drive nuclear physics experiments, and underpin high-precision cosmology. To first order, the outcome is governed by nuclear physics, a property often described as stellar amnesia. Recently, this stellar amnesia has begun to be broken by the nearly universal detection of…

astro-ph.GA

Widefield Arecibo Virgo Extragalactic Survey: II. Characterizing the HI properties and environment of the WAVES South region

V. Partík, R. Taylor, R. Minchin

Context. Galaxy clusters are extreme environments where interactions with the hot intracluster medium drive rapid galaxy evolution. These processes can result in the formation of optically dark gas clouds, as previously observed in Virgo and other clusters. Aims. We investigate the distribution and properties of neutral hydrogen (HI) in two large adjoining regions of the Virgo cluster to understand how the cluster environment influences galaxy transformation. Specifically, we examine the gas con…

physics.hist-phastro-ph.EPastro-ph.SR

From the Earth to the Sun

Dieynaba Young

This year marks 360 years since the founding of the French Academy of Sciences. This is the story of the academy's daring 17th century expedition to measure the Earth-sun distance. A truncated version first appeared in National Geographic Magazine; the following is closer to the original draft, with updated information and references.

physics.data-anastro-ph.COastro-ph.GAcs.LGhep-ex

Unknown Unknowns: Model Misspecification in Machine Learning for Physics

Juan Cruz-Martinez, Carolina Cuesta-Lazaro, Alexander Held, Michael Kagan

Machine learning is now a central tool for solving inverse problems in particle physics and astronomy. Models are trained on simulation and deployed on real data, raising the question not just of whether they fit, but of whether they are wrong in ways we did not anticipate: the unknown unknowns. This challenge of model misspecification is not unique to machine learning. In physics, misspecification is sometimes exactly what we want to find: new discoveries appear as failures of existing models.…

astro-ph.HEastro-ph.SR

Radio Monitoring of Classical Novae using the ASKAP Variable and Slow Transients Survey

Aishani Majumder, David L. Kaplan, Laura N. Driessen, Ashna Gulati, Tara Murphy, Dougal Dobie

We present a search for radio emission from classical novae at 887.5 MHz using data from the Australian SKA Pathfinder Variable And Slow Transient (VAST) survey. We cross-matched 43 optically discovered classical novae that erupted between 2021 September and 2025 November within the 1200-square-degree Galactic survey footprint, and found three which show significant radio emission: V6598 Sgr, V1716 Sco, and V1723 Sco. To analyse their radio light curves, we use both thermal free-free and non-the…

astro-ph.HEastro-ph.SR

Radio Monitoring of Classical Novae using the ASKAP Variable and Slow Transients Survey

Aishani Majumder, David L. Kaplan, Laura N. Driessen, Ashna Gulati, Tara Murphy, Dougal Dobie

We present a search for radio emission from classical novae at 887.5 MHz using data from the Australian SKA Pathfinder Variable And Slow Transient (VAST) survey. We cross-matched 43 optically discovered classical novae that erupted between 2021 September and 2025 November within the 1200-square-degree Galactic survey footprint, and found three which show significant radio emission: V6598 Sgr, V1716 Sco, and V1723 Sco. To analyse their radio light curves, we use both thermal free-free and non-the…

astro-ph.SRastro-ph.HE

JWST Detects a Dusty AGB-like Source Before the Type Ia-CSM Supernova 2026sqf

Tamás Szalai, Dan Milisavljevic, Noah Zimmer, Braden Garretson, Thomas Moore, Schuyler D. Van Dyk, Anan Lu, Selcuk Topal et al.

Supernova (SN) 2026sqf recently appeared in the nearby face-on spiral galaxy NGC 3310 and has shown signs of strong interaction with a circumstellar medium (CSM). Such intense interaction, rare among nearby SNe, offers a valuable opportunity to reveal details on the origin and nature of its progenitor system. We analyzed the early-phase spectra and light curves (LCs) of SN 2026sqf. The general shapes of the observed spectra, the strengths of the emission lines, and the LC evolution all suggest t…

astro-ph.GAastro-ph.SR

Differential Reddening and Extinction Law Analyses of Galactic Open Clusters

Xiaohan Chen, Shu Wang, Xiaodian Chen

Extinction significantly affects open cluster parameters and their use in studies of Galactic structure, yet homogeneous large sample measurements of open cluster extinction properties remain limited. Using Gaia-era open cluster member samples combined with multi-band photometry and stellar parameters, we derive color excesses of member stars and provide the homogeneous characterization of the mean reddening, differential reddening, and color excess ratio (CER) at the cluster scale. Differential…

astro-ph.GA

Radio Properties of Narrow-Line and Broad-Line Seyfert 1 Galaxies

K. É. Gabányi, S. Komossa, A. Mezősi, E. Forgács-Dajka, S. Frey

Narrow-line Seyfert 1 (NLS1) galaxies host active galactic nuclei (AGN) with narrow optical emission lines of the broad-line region. This is often explained with a relatively lower mass of the central supermassive black hole and super-Eddington accretion. We compared the radio properties of large samples of NLS1 and broad-line Seyfert 1 (BLS1) galaxies compiled from the Sloan Digital Sky Survey. We cross-matched the NLS1 and BLS1 samples with the Faint Images of the Radio Sky at Twenty-Centimete…

astro-ph.HEastro-ph.GA

X-ray Flaring and Variability in NGC 1275, the Heart of the Perseus Cluster

Sarah Ketchum, Jon M. Miller, S. W. Allen, Doyee Byun, Tianyin Hu, Missagh Mehdipour, Veronica Tananko, Xin Xiang et al.

NGC 1275 is the central galaxy in the Perseus Cluster. The active galactic nucleus (AGN) within NGC 1275 is notable for its strong and variable radio activity, tied to the production of radio jets that inflate large bubbles in the hot intracluster medium (ICM). High spatial resolution X-ray imaging can separate the AGN from the bright ICM, but monitoring the mass accretion rate onto the black hole and establishing disk-jet connections in NGC 1275 requires a high cadence. Here, we report on X-ray…

astro-ph.EPastro-ph.SR

Stellar tidal systematics in apsidal-motion searches for circumbinary planets: CH Ind and SW CMa

Qunfeng Jiang

Thornton et al. (2026) reported 27 non-transiting circumbinary-planet candidates from excess apsidal motion in TESS eclipsing-binary timings. The classical stellar contribution is sensitive to target-specific radii, apsidal constants $k_2$, and rotation. We re-evaluate two evolved, double-lined eclipsing binaries in that sample: the pulsating system CH Ind and the Am system SW CMa. Their component masses and radii have been measured in dedicated binary studies, allowing the stellar contribution…

astro-ph.HEastro-ph.GA

The low luminosity end of Galactic HMXBs with eROSITA: Establishing a luminosity floor for accreting BeXRBs

Aafia Zainab, Philipp Thalhammer, Nico Zalot, Artur Avakyan, Jakob Stierhof, Ekaterina Sokolova-Lapa, Victor Doroshenko, Victoria Grinberg et al.

We present a first look at the Galactic population of heretofore known HMXBs as observed by SRG/eROSITA during its first four surveys. eROSITA's sensitivity of $\sim10^{-13}\,\mathrm{erg}\,\mathrm{s}^{-1}\,\mathrm{cm}^{-2}$, translating to $10^{32}$-$10^{34},\mathrm{erg}\,\mathrm{s}^{-1}$ in luminosity for most known HMXBs in the Milky Way, has thus far never been reached by any wide-area survey instrument. We present the extended log N-log L distribution of known HMXBs reaching down to $10^{32}…

astro-ph.IMastro-ph.CO

Optical concept model of the future cosmology project BISOU

Morgane Loquet Le Gall, Bruno Maffei, Pierre Guiot, Creidhe O'Sullivan, Neil Trappe

We present an optical analysis of BISOU (Balloon Interferometer for Spectral Observations of the primordial Universe), an astronomical balloon-borne pathfinder spectrometer developed as part of a preparatory study for a future space mission aiming at measuring spectral distortions of the cosmic microwave background (CMB). The BISOU optical system is based on a differential polarizing Fourier Transform Spectrometer (FTS) that receives inputs from both a sky-facing telescope and an internal calibr…

astro-ph.EP

Assessing Planetary Stability and Long-Term Habitability in Nearby Stellar Binaries: 70 Oph, 36 Oph, $γ$ Leo

Alyssa R. Jankowski, Juliette Becker, Catherine A. Clark, Eric E. Mamajek, Jessie L. Christiansen, Yiting Li, Eduardo Bendek, Daniella Gagliuffi et al.

Binary stars are common and have the potential to host habitable planets, which may reside in more complex habitable zones as compared to planets orbiting single stars. In this work, we use numerical simulations to assess the possibility that bright, nearby stellar multiples 36 Oph, 70 Oph, and $γ$ Leo could host habitable planets. We find that for the 36 Oph A/B system and for the 70 Oph A/B system, the stars can support planets residing in permanently habitable zones with low ejection rates an…

astro-ph.EP

Assessing Planetary Stability and Long-Term Habitability in Nearby Stellar Binaries: 70 Oph, 36 Oph, $γ$ Leo

Alyssa R. Jankowski, Juliette Becker, Catherine A. Clark, Eric E. Mamajek, Jessie L. Christiansen, Yiting Li, Eduardo Bendek, Daniella Gagliuffi et al.

Binary stars are common and have the potential to host habitable planets, which may reside in more complex habitable zones as compared to planets orbiting single stars. In this work, we use numerical simulations to assess the possibility that bright, nearby stellar multiples 36 Oph, 70 Oph, and $γ$ Leo could host habitable planets. We find that for the 36 Oph A/B system and for the 70 Oph A/B system, the stars can support planets residing in permanently habitable zones with low ejection rates an…

astro-ph.IMastro-ph.CO

Optical development of the BISOU breadboard

Morgane Loquet Le Gall, Creidhe O'Sullivan, Bruno Borgo, Clémence De Jabrun, Valentin Sauvage, Neil Trappe, Bruno Maffei

BISOU (Balloon Interferometer for Spectral Observations of the primordial Universe) is an astronomical balloon-borne pathfinder developed as part of a preparatory study for a future space mission aimed at measuring spectral distortions of the cosmic microwave background (CMB). A laboratory breadboard of the instrument is being developed at the Institut d'Astrophysique Spatiale (IAS), enabling the characterization of subsystems and instrument systematic effects, particularly in the optical system…

astro-ph.IMastro-ph.CO

FOSSIL's preliminary thermal architecture

Valentin Sauvage, Clémence de Jabrun, Anaïs Besnard, Bruno Borgo, Ivan Charles, Jean-Marc Duval, Bruno Maffei, Sylvain Martin et al.

FOSSIL (FTS fOr CMB Spectral diStortIon expLoration) is a proposed ESA M8 mission tailored to measure the spectral distortions monopole of the Cosmic Microwave Background (CMB) with a sensitivity three orders of magnitude beyond the COBE/FIRAS legacy measurement. Achieving this sensitivity demands an extraordinarily challenging cryogenic architecture: the scientific instrument must be maintained at 4.5 K, while the detector focal plane assembly operates at 50 mK. This paper presents an overview…

astro-ph.COastro-ph.GA

Cosmography with DESI-DR1 Cosmic Chronometers: Direct H(z) measurements from Luminous Red Galaxy ages

Carlos A. Álvarez, Marcos M. Cueli, Balakrishna S. Haridasu, Michele Moresco, Martina Torsello, Alessandro Bressan, Lumen Boco, Luigi Danese et al.

Providing robust redshift estimates for almost 3 million luminous red galaxies (LRGs), the Dark Energy Spectroscopic Instrument (DESI) offers a unique opportunity to test the expansion rate of the Universe with independent approaches. We apply the cosmic chronometer method to derive new, independent constraints on the Hubble parameter at 0.3<z<1.2 from the differential age evolution of DESI LRGs. We select spectra applying spectroscopic cuts to ensure sample purity and remove contamination by st…

astro-ph.EPastro-ph.IM

A Radon-Transform Perspective on Exoplanet Transits

Shotaro Tada

Transit light curves are usually analyzed under the assumption that the transiting planet has a circular sky-projected silhouette. However, planetary rotation, tides, rings, or atmospheric inhomogeneities can produce non-circular silhouettes. This raises the question of what information transit light curves can provide about the underlying two-dimensional attenuation map. In this paper, we show that, in a simple and transparent limit, the time derivative of the transit light curve during ingress…