研究動向

astro-ph.GA2026年9月1日

Extragalactic Stellar Streams in Time-Dependent Cosmological Halos

Sarah Pearson, Jacob Nibauer, Emily C. Cunningham, Adrian M. Price-Whelan, Adrien C. R. Thob, Arpit Arora, Robyn E. Sanderson

Upcoming and ongoing surveys will detect thousands of stellar streams around galaxies other than the Milky Way. Studies from the Milky Way have shown that time-dependent evolution of the Galactic halo plays a key role in shaping stellar streams, but remains unexplored for extragalactic stellar streams. We use the FIRE-2 m12m cosmological zoom-in simulation, mock observed as an extragalactic system including three stellar streams, to examine how halo time-dependence affects progenitor and host ha…

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astro-ph.IMastro-ph.EPastro-ph.SR2026年9月1日

Amortized Opacity Marginalization Improves C/O Interval Calibration for Brown-Dwarf Retrievals

Kellen Heraty

Molecular line lists disagree at a level that measurably shifts retrieved C/O, so retrievals conditioned on a single list omit a dominant systematic from their error bars. Classical marginalization re-runs a full retrieval under K opacity realizations per object. We move that cost into simulation: while generating the training set we randomize opacities (smooth multiplicative Fourier fields in $\logν$ plus a discrete line-list mixture, under a deliberately broad prior informed by measured inter-…

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astro-ph.GA2026年9月1日

Detection of a triple nucleus in the Wolf-Rayet composite Sy 2 galaxy NGC 6764

Jochen Heidt, Francisco Pozo Nuñez, Nina Mackensen, Magdalena Vukojevic, David Thompson

We report adaptive-optics Ks-band imaging of the composite Seyfert 2 and Wolf-Rayet galaxy NGC 6764 (D = 32 Mpc), obtained with LUCI/SOUL at the Large Binocular Telescope. The nucleus resolves into three compact sources with pairwise projected separations of 0.07-0.20 arcsec, corresponding to 11.0-30.9 pc. All three have indistinguishable H, Ks, H2, and Br-gamma colours, so photometry alone cannot separate accretion from star formation. The system is consistent with a Seyfert nucleus and two sta…

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astro-ph.SRastro-ph.GA2026年9月1日

SPIRITS 19q: Dust Production by a Subsolar-metallicity Carbon-rich Wolf-Rayet Star in NGC 2403

Sam Rose, Ryan M. Lau, Jacob E. Jencson, Mansi M. Kasliwal, Andreas A. C. Sander, Howard E. Bond, Michael F. Corcoran, Izumi Endo et al.

We present JWST/NIRSpec IFU observations of SPIRITS 19q, the highly dust-producing carbon-rich (WC) binary candidate located in a subsolar-metallicity region of the nearby spiral galaxy NGC 2403. The observations, taken in April of 2024, confirm the association of a dusty outburst observed in 2019 by the Spitzer Space Telescope with an early-type WC star. Using models from the Potsdam Wolf-Rayet (PoWR) LMC model grid we find that the WC star of SPIRITS 19q likely has an especially high mass-loss…

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astro-ph.SR2026年9月1日

Age Discrepancy in Three Galactic Cepheid Binaries

Sashwat Prasadh, Hilding R. Neilson, Nancy Remage Evans

SV Per, RW Cam, and KN Cen are Galactic classical Cepheids found in binary systems along with B-type companions. Each system exhibits an ``apparent age discrepancy", where the Cepheid appears significantly younger than its companion. We compute stellar evolution tracks using the MESA code and compare them with these stars on the Hertzsprung-Russell diagram to estimate the masses and the corresponding ages. We find that, for two of the systems, the companions appear to be between 1.5 times to dou…

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astro-ph.EP2026年9月1日

An Upper Limit on Turbulent Viscosity in the Circumjovian Nebula

Konstantin Batygin, Fred C. Adams

Circumplanetary disks are open, dynamic systems sustained by a meridional circulation that draws gas and dust from the parent nebula along nearly polar streamlines, and ultimately returns some of this material through a viscously driven, in-plane outflow. In such a disk, the water ice line acts as a site of solid-mass accumulation: inward-drifting icy solids sublimate interior to the ice line, the resulting vapor is advected outward by the gas, and recondensation beyond the ice line resets the m…

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astro-ph.GAastro-ph.CO2026年9月1日

Formation of Heavy Seed Black Holes and Little Red Dots-like Compact Clusters in Metal-enriched Star-forming Regions

Sunmyon Chon, Shingo Hirano, Ke-Jung Chen, Volker Springel

The origin of supermassive black holes (SMBHs) in the early Universe remains uncertain. While the classical direct-collapse scenario requires pristine gas exposed to intense Lyman-Werner (LW) radiation, recent JWST observations suggest that early growing BHs may reside in compact, metal-enriched environments. We investigate early BH formation using a cosmological radiation-hydrodynamic simulation that self-consistently follows the formation and evolution of rapidly accreting supermassive stars (…

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astro-ph.EPcs.LG2026年9月1日

Accelerating Chemical Kinetics for Exoplanet Atmospheres using Neural Networks

Isaac Malsky, Xi Zhang, Tiffany Kataria, Matthew Graham, Ziyu Huang, Boris Bonev, Shang-Min Tsai, Elspeth K. H. Lee et al.

Observations increasingly reveal the coupled radiative, chemical, and dynamical processes that shape exoplanet atmospheres. Interpreting these atmospheres requires models that can capture this complexity. However, multidimensional models remain fundamentally limited by computational cost, and answering key questions requires simulating the governing physical mechanisms at speeds classical methods cannot achieve. As a result, models often rely on simplifying approximations, such as equilibrium ch…

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astro-ph.SR2026年9月1日

The Formation of Very Close Binary Stars

Maxwell Moe

The majority of very close binaries (orbital periods P < 5 days) are in triples. Previous studies surmised that the tertiary hardened the inner binary via Kozai-Lidov cycles coupled with tidal friction. Alternatively, the trend could be due to a common origin, e.g., more massive molecular cores and protostellar disks are more likely to fragment twice into a triple and harden the inner binary to very short periods via disk migration. Disk migration occurs during the embedded Class I protostellar…

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astro-ph.EPastro-ph.SR2026年9月1日

Where planetary solids survive sublimation around young and hot white dwarfs

Dimitri Veras, Keiji Ohtsuki, Rafael Martinez-Brunner, Takato Nishio, Ryo Tamon

All observed planetary systems orbiting single white dwarfs have lived through the hot stellar transition from an asymptotic giant branch star. In this post-nebular transition period, the initial conditions for planetary system evolution throughout white dwarf cooling are established. The hottest ($\gtrsim$ 20,000 K) and youngest ($\lesssim$ 20 Myr-old) white dwarf planetary system host stars differ significantly from their canonical older and colder counterparts by failing to support solid body…

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astro-ph.IM2026年9月1日

The Canadian Galactic Emission Mapper (CGEM): A Cosmic Microwave Foreground Experiment

Parham Zarei, Pedro Villalba-González, Mandana Amiri, Charles L. Bennett, Guinevere Berg, Mark Halpern, Gary Hinshaw, Gordon Lacy et al.

The Canadian Galactic Emission Mapper (CGEM) is a 4-meter single-dish radio telescope located at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, Canada. CGEM is designed to map polarized Galactic synchrotron emission across the entire northern sky at 8-10 GHz with 1 MHz frequency resolution and 0.5 degree angular resolution. Its goal is to obtain high-fidelity, low-noise maps of polarized Galactic synchrotron radiation, at frequencies where synchrotron dominates, in order to pr…

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gr-qcastro-ph.GA2026年9月1日

A Fast and Scalable Transformer Pipeline for Binary Black Hole Detection

Chayan Chatterjee, Abigail Petulante, Haowei Fu, Yang Hu, Roy Lau, Karan Jani

With the projected increase in the detection rate of compact-binary coalescences in the coming decade, there is critical need to develop fast, robust, and scalable alternatives to matched filtering for gravitational-wave searches. Transformer models have revolutionized natural language and audio processing but their application to gravitational-wave astronomy is still largely unexplored. In this work, we introduce \castor, a transformer-based coincident search pipeline for detecting binary black…

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astro-ph.SRphysics.space-ph2026年9月1日

Direct Measurement of Polar Coronal Hole-like Solar Wind in its Acceleration Phase

Samuel T. Badman, Yeimy J. Rivera, Michael L. Stevens, Mari Paz Miralles, Steven R. Cranmer, Andrea Verdini, Lynn B. Wilson, Xiangyu Wu et al.

The early evolution of fast polar coronal hole (PCH) solar wind remains largely unconstrained by in situ measurements. In March 2025, Parker Solar Probe (Parker) at its closest approach of 9.86 Solar Radii ($R_\odot$) measured outflow from a large equatorial coronal hole (ECH) which was also measured at 1\,au and at intermediate distances by Solar Orbiter (also near its perihelion). At 1\,au the stream properties are consistent with PCH properties established by Ulysses. The stream was measured…

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astro-ph.SRhep-phnucl-th2026年9月1日

A Data-Driven Model for $r$-Process Production Patterns

Chen-Qi Li, Yong-Zhong Qian, Axel Gross, Zewei Xiong

Using the elemental abundances in 68 metal-poor (MP) stars, we present a data-driven model for $r$-process production patterns covering Sr to U. We show that essentially all the $r$-process patterns in those and other test stars can be adequately explained as mixtures of Patterns 1 and 2, which provides theoretical insights into the empirical categories of limited-$r$, $r$-I, and $r$-II stars. We carry out an extensive survey of the yield templates produced by parametric $r$-process calculations…

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astro-ph.SR2026年9月1日

TESS Observations of Seven Newly Identified High-amplitude $δ$ Scuti Stars

Chenglong Lv, Ali Esamdin, Amir Hasanzadeh, Shuguo Ma, TaoZhi Yang, Rivkat Karimov

We report seven newly identified high-amplitude $δ$ Scuti (HADS) stars. Among them, two stars (TIC 30977864 and TIC 387379145) exhibit pure radial pulsation without the excitation of non-radial modes. TIC 30977864 is classified as a double-mode HADS star, while the other four stars potentially show triple-mode HADS behavior. TIC 112682462 and TIC 255603395 closely resemble RR Lyrae stars based on their light curves, position in the period-luminosity diagram, and the period-ratio diagram. However…

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astro-ph.SR2026年9月1日

Statistical analysis of asteroseismic indices and stellar parameters of TESS-observed $δ$ Scuti stars

C. Lv, A. Esamdin, A. Hasanzadeh, M. Ghazinejad, J. Pascual-Granado, G. M. Mirouh, R. Karimov

We analyze the statistical properties and asteroseismic indices of delta Scuti stars observed during TESS Cycle 4. Using 2 minute cadence photometry and Fourier analysis, we identified 765 delta Scuti stars in Sectors 40-55, including 179 objects with low-resolution stellar parameters from LAMOST. We examined the distributions of their pulsation and stellar parameters using values from the TESS Input Catalog and LAMOST. Most targets lie within the classical instability strip, follow the period-l…

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astro-ph.SR2026年9月1日

Discovery and Characterization of Three New High-amplitude delta Scuti Stars from TESS Observations

Chenglong Lv, Ali Esamdin, J. Pascual-Granado, Guojie Feng, Haozhi Wang, Rivkat Karimov, Bolkin Juraev, Shuhrat A. Ehgamberdiev et al.

We report the discovery and detailed analysis of three new high-amplitude δ Scuti (HADS) stars, TIC 408074920, TIC 189714989, and TIC 34137913, identified from Transiting Exoplanet Survey Satellite short-cadence observations. Fourier analysis reveals dominant radial modes accompanied by rich harmonic structures in all three stars, confirming their HADS classification. In addition, TIC 189714989 exhibits clear symmetric side peaks around the radial harmonics, indicative of amplitude and/or phase…

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astro-ph.GA2026年9月1日

ELVES-Dwarf. II. A Systematic Search for Satellite Systems of Dwarf Galaxies in the Local Volume

Jiaxuan Li, Jenny E. Greene, Shany Danieli, Scott G. Carlsten, John Moustakas, Marla Geha, Masayuki Tanaka, Fangzhou Jiang et al.

We present the Exploration of Local VolumE Satellites of Dwarf Galaxies (ELVES-Dwarf) survey, a systematic census of satellite systems around dwarf hosts in the Local Volume. Our final sample comprises 39 predominantly isolated hosts with stellar masses $10^{7} 10^5\,M_\odot$ around the 39 hosts. Above our fiducial completeness threshold of $M_\star\gtrsim10^{5.7}\,M_\odot$ and within the projected virial radius, 21 hosts have no confirmed satellites, 10 have one, six have two, and two have four…

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astro-ph.EP2026年9月1日

Three-dimensional circumplanetary flows in a PDS 70c-inspired system: hydrodynamic simulations with FARGO3D and analysis with FARGOpy

Alejandro Murillo-Gonzalez, Jorge I. Zuluaga, Matias Montesinos

The detection of circumplanetary material around the forming planet PDS~70c provides a valuable setting for studying three-dimensional gas accretion during giant-planet formation. We present three-dimensional hydrodynamic simulations with FARGO3D for a locally isothermal protoplanetary disk, adopting system-motivated stellar, orbital, and disk parameters and planetary masses of $2$, $4$, and $8,M_{\rm Jup}$, all above the local thermal mass. The locally isothermal prescription provides a control…

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astro-ph.GA2026年9月1日

Accretion-disk sizes in two quasars with interferometrically resolved broad-line regions at $z=2.3$ and $z=4.0$

Francisco Pozo Nuñez, Eduardo Bañados, Swayamtrupta Panda, Amit Kumar Mandal, Bozena Czerny, Jochen Heidt

We present the first direct comparison between accretion-disk (AD) and broad-line region (BLR) sizes in quasars at z > 2, combining continuum reverberation mapping with interferometric BLR constraints from GRAVITY and GRAVITY+. Using medium-band photometric monitoring with the MPG/ESO 2.2 m telescope, we measure inter-band continuum lags in SDSS J092034.17+065718.0 at z = 2.33 (J0920) and SMSS J052915.80-435152.0 at z = 3.96 (J0529), among the most luminous quasars known (Lbol ~ 10^48 erg s^-1).…

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astro-ph.IM2026年9月1日

The Hopkins Ultraviolet Telescope: A Historical and Personal Retrospective

William P. Blair

This manuscript documents the inception and development of the Hopkins Ultraviolet Telescope (HUT) project, which was a component of the Astro Observatory payload that flew on two Spacelab shuttle missions in the 1990s. The discussion places the HUT project in the context of the times and highlights the importance of its acceptance by NASA in 1980 to the growth and development of astrophysics at the Johns Hopkins University. Personal recollections from the author, including a detailed descriptio…

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astro-ph.EPastro-ph.SR2026年9月1日

A JWST transiting survey of FGK stellar limb darkening: empirical evidence for quadratic laws and atmospheric model comparisons

David K. Sing, Joshua D. Lothringer, Jeff A. Valenti, Natalie H. Allen, Katherine A. Bennett, Carlos Gascón, Mei Ting Mak, Patrick McCreery et al.

We present a study of stellar limb-darkening using JWST transit observations of seven exoplanets orbiting FGK host stars, spanning 4200-6800 K. The wide wavelength coverage and high S/N of NIRISS/SOSS and NIRSpec/PRISM enable precise constraints on the wavelength-dependent limb-darkening. Using Bayesian model selection, we find that the quadratic limb-darkening law is statistically preferred over higher-order laws for most FGK stars, recovers consistent intensity profiles for $>$95% of the stell…

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astro-ph.IM2026年9月1日

Simulation and development of astrophotonic H-band nulling beam combiner for the CHARA Array

Samantha G. Morrison, Pradip Gatkine, Michael P. Fitzgerald

Nulling interferometry is a promising method for direct detection and characterization of faint stellar companions such as exoplanets and faint binary sources. The dominant constraint on instrument performance is instability noise from vibrations, thermal expansions, and other systematic sources. Photonic instruments have footprints of a few centimeters and enable advanced light control architectures. Astrophotonic implementations can include active phase control via Mach-Zehnder interferometers…

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astro-ph.IM2026年9月1日

Flux jump correction in the QUBIC TES data pipeline

Belen Costanza, Lucas Merlo Azzolina, Claudia G. Scoccola, Nahuel Miron Granese, Elia Battistelli, Jean-Christophe Hamilton, Michel Piat, Damien Prele et al.

Flux jumps occur in the readout electronics of Transition Edge Sensor (TES) detectors coupled to Superconducting Quantum Interference Devices (SQUIDs), as a consequence of the periodic transfer function of SQUIDs in the superconducting regime. These events manifest as discontinuities in the Time Ordered Data (TOD) and can significantly degrade the quality of the measured signals. In this work, we present an automated pipeline to identify and correct flux jumps in the calibration data of the QUBI…

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astro-ph.SR2026年9月1日

A Probabilistic Framework for Incorporating Helioseismic Far-Side Active Regions into SFT Models

Bibhuti Kumar Jha, Lisa A. Upton, K. D. Leka, Ruizhu Chen, Junwei Zhao, Shea Hess Webber, Ignacio Ugarte-Urra, Kiran Jain et al.

Surface Flux Transport (SFT) models are routinely used to model the Sun's photospheric magnetic field and provide inner boundary conditions for coronal and heliospheric models, yet they remain fundamentally limited by the lack of direct information about flux emergence on the far side of the Sun. To address this, we develop a framework for incorporating helioseismic images of far-side active regions (HIFAR), into the Advective Flux Transport (AFT) model. Using near-simultaneous magnetic flux map…

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gr-qcastro-ph.HE2026年9月1日

Gravitational waves from core collapse of rotating very-massive stars: 3D numerical relativity computation

Alan Tsz-Lok Lam, Masaru Shibata, Sho Fujibayashi

We numerically study the collapse of rotating, very-massive stellar cores with masses of $\approx 200$, $300$, $500$, and $1100M_\odot$ into black holes using both axisymmetric and three-dimensional (3D) numerical relativity. Our results indicate that when the dimensionless spin of the resulting black hole exceeds 0.8, a massive disk consistently forms around it. These massive, compact disks, carrying more than about 10\% of the black hole's mass, are prone to non-axisymmetric deformations that…

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astro-ph.GA2026年9月1日

The gradual decline of Ly$α$ visibility in the CANDELS fields: evidence for the combined effects of galaxy evolution and reionization

L. Napolitano, L. Pentericci, A. Ferrara, M. Llerena, M. Dickinson, A. Calabrò, S. L. Finkelstein, R. Begley et al.

We investigate the evolution of Ly$α$ visibility and the physical properties of Ly$α$ emitters (LAEs) across the five CANDELS fields using publicly available JWST/NIRSpec PRISM spectroscopy. Our catalog comprises 3446 spectroscopically confirmed sources at 4 $\leq $ z 3) LAEs. We measure the fraction of LAEs with EW$_0$ > 25A (X$_{\mathrm{Lyα}}$) and trace its redshift evolution in two UV luminosity bins, namely -20.25 6. We also investigate the physical properties of both LAEs and the full SFG…

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astro-ph.HE2026年9月1日

GRMHD Simulations of Accreting Proto-Magnetars II. Implications for r-process Nucleosynthesis

Tejas Prasanna, Kyle Parfrey, Brian D. Metzger, Ore Gottlieb, Andrei Beloborodov, Koushik Chatterjee

Newly formed, rapidly spinning, strongly magnetized neutron stars ("millisecond proto-magnetars") can arise in collapsars, neutron star mergers, or white-dwarf accretion-induced collapse, and are often surrounded by compact accretion disks. At accretion rates of ~0.1 Msun/s, these disks can become neutron rich and power outflows capable of rapid neutron-capture (r-process) nucleosynthesis. In Paper I, we presented axisymmetric GRMHD simulations of accretion onto such proto-magnetars and showed h…

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astro-ph.GA2026年9月1日

Local Heavily Obscured Active Galaxies Observed With Chandra (I): Spectral Properties of the Nuclear and Extended X-ray Emission

R. Middei, G. Fabbiano, A. Trindade Falcão, D. Ł. Król, W. P. Maksym, M. Elvis

The Chandra X-ray Observatory has revealed that kiloparsec-scale extended X-ray emission is commonly associated with heavily absorbed ($\log (N_{H}$/cm$^{-2})\,>\, 23$) Active Galactic Nuclei (AGN) in the local Universe. We present a homogeneous spatially resolved spectral analysis of a sample of nearby obscured AGN observed with deep ($>100$~ks) Chandra/ACIS exposures and all associated with extra-nuclear extended emission. Exploiting the sub-arcsecond resolution of Chandra, we separate unresol…

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astro-ph.COastro-ph.GA2026年9月1日

TDCOSMO XXVIII. The Hubble constant from the quadruply lensed quasar J1537$-$3010 with precise time delays

A. Galan, A. G. Schweinfurth, S. H. Suyu, D. P. Johnson, A. Chawla, D. Sluse, G. V. Kharchilava, E. Buckley-Geer et al.

We present the first measurement of the Hubble constant ($H_0$) from the quadruply-lensed quasar J1537$-$3010, which has optically-measured time delays at $\sim2 \%$ precision. We combine these delays with multi-band imaging data from the Hubble Space Telescope (HST) and model the system with two independent software and teams. We adopt a mass profile that is maximally degenerate with $H_0$ to fully incorporate the mass-sheet degeneracy in the error budget, with nuisance parameters constrained b…

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