研究動向

astro-ph.GA2026年8月8日

CO Structures with Narrow Lines in Nearby Quiescent Regions

Ruilin Xia, Yang Su, Shiyu Zhang, Xuepeng Chen, Ji Yang, Yan Gong, Yuehui Ma, Yan Sun et al.

Using CO data from Phase I of the Milky Way Imaging Scroll Painting (MWISP) survey, we present a systematic study of molecular structures with narrow lines. We identify 57 CO structures, most of which exhibit low densities and subsonic/transonic turbulence. Among them, structures with large projected areas and diffuse, sheet-like geometries are identified as veil clouds. The low LSR velocities and the concentration of these CO structures toward both the Galactic center (e.g., Ophiuchus, Aquila)…

詳細を見る →

gr-qcastro-ph.IM2026年8月8日

Spotlight searches for continuous gravitational waves triggered on radiometer candidates in LIGO O4a data

Alan M. Knee, Keith Riles, Ling Sun

We report on a follow-up search for continuous gravitational waves (CWs) targeting sub-threshold candidates from the O4a LIGO-Virgo-KAGRA (LVK) all-sky all-frequency (ASAF) directed radiometer analysis. We analyze a total of $562$ ASAF candidates using Advanced LIGO data from the first part of the fourth LVK observing run. Each candidate comprises a narrow $1/32$ Hz frequency band paired with a ${\sim}13$ deg$^2$ sky pixel, defining the search parameter space for our analysis. Our search pipelin…

詳細を見る →

gr-qcastro-ph.HEnucl-th2026年8月8日

Oscillations of Dissipative Neutron Stars: The Impact of Hyperonic Reaction Rates

Suprovo Ghosh, Alexander Haber, Nils Andersson, Andrew Rhys Counsell

Tidal excitations of stellar oscillation modes during binary neutron-star inspirals offer a powerful probe of the composition of dense matter at supranuclear densities. Chemical equilibration plays a crucial, but often neglected, role in stellar perturbation calculations. If the chemical equilibration timescale is comparable to the oscillation timescale, then viscous effects can damp the modes. If the reactions are fast, some modes can completely disappear since their restoring force vanishes. T…

詳細を見る →

math.DSastro-ph.EPastro-ph.IMcs.GRmath.NA2026年8月8日

GPU-Accelerated Orbit Propagation with High-Fidelity Solar Radiation Pressure Modeling

Leandro Zardaín, Ariadna Farrés, Anna Puig, Kevin Muntal, Albert Mir

Solar Radiation Pressure (SRP), the force exerted by photons emitted by the Sun, is one of the main non-gravitational perturbations affecting spacecraft trajectories, making its accurate modeling essential for high-fidelity orbit propagation. While physically-based ray-tracing models improve SRP accuracy, their computational cost becomes a limitation during numerical integration, where the SRP force must be evaluated repeatedly throughout the trajectory propagation. This paper investigates the i…

詳細を見る →

astro-ph.GAastro-ph.CO2026年8月7日

Testing dark matter models and modified gravity theories with spatially resolved HI observations

Federico Lelli, Antonino Marasco, Timothy A. Davis, Nathan Deg, Jonathan Freundlich, Gyula I. G. Jòzsa, Peter Kamphuis, Pavel E. Mancera Piña et al.

Understanding the nature of dark matter (DM) is one of the most pressing questions of modern physics. The flat rotation curves of galaxies, especially the extended HI rotation curves from radio observations at 21 cm, played a key historical role to establish the DM problem and continue to be a major tool to test different galaxy formation models, particle DM models, and modified gravity theories. The SKA observatory will revolutionize the study of HI rotation curves thanks to its unprecedented a…

詳細を見る →

astro-ph.HEastro-ph.SR2026年8月7日

Multi-dimensional NLTE radiative transfer for a double detonation Type Ia explosion model in the photospheric phase

F. P. Callan, L. J. Shingles, S. A. Sim, C. E. Collins, J. M. Pollin, R. Pakmor, S. Gronow, F. K. Roepke et al.

Previous radiative transfer calculations have shown that both multi-dimensionality and NLTE (non local thermodynamic equilibrium) effects impact the synthetic observables predicted for Type Ia supernova explosion models. Here we carry out a 2D NLTE radiative transfer simulation in the photospheric phase for a double detonation model with a 1 M$_{\odot}$ carbon-oxygen core and 0.02 M$_{\odot}$ helium shell. The predicted observables demonstrate that departures from both spherical symmetry and loc…

詳細を見る →

astro-ph.IMphysics.ins-det2026年8月7日

WST, the Wide-field Spectroscopic Telescope: dispersing elements

Andrea Bianco, Michele Frangiamore, Anna Brucalassi, Dimitri Buffat, Corentin Cudennec, Kjetil Dohlen, Alexandre Jeanneau, David Lee et al.

The Wide-field Spectroscopic Telescope (WST) is a proposed 12-m class facility entirely dedicated to spectroscopic surveys, combining a high-multiplex multi-object spectrograph operating at low (MOS-LR) and high (MOS-HR) spectral resolution with a giant panoramic integral-field spectrograph (IFS), all three operating in parallel. Diffraction gratings are the key dispersing elements of all three instruments and, given the very large number and size of the units required, drive critical trade-offs…

詳細を見る →

astro-ph.GA2026年8月4日

Discovery of the Distant, Ultra-Faint Milky Way Satellite Aquarius IV with the Vera C. Rubin Observatory Early Data Preview 2

William Cerny, Aashay Pai, Alex Drlica-Wagner, Andrew B. Pace, Peter S. Ferguson, Marla Geha, Chin Yi Tan, Sasha Campana et al.

We present the discovery of Aquarius IV (Rubin J2201$-$0234) -- the first ultra-faint Milky Way satellite to be identified using data from the Vera C. Rubin Observatory. This system was detected at $\sim$8$σ$ significance using Rubin Early Data Preview 2 (EDP2) photometry and independently confirmed at $\sim$6$σ$ significance in archival Dark Energy Camera imaging. Jointly fitting its morphology and distance, we find that Aquarius IV is a low-luminosity ($M_V=-1.9^{+0.6}_{-1.0}$), compact ($r_{1…

詳細を見る →

astro-ph.IMastro-ph.GA2026年8月4日

SDSS-V Local Volume Mapper (LVM): Dithered Data Cube Reconstruction with 3dcubegen

H. J. Ibarra-Medel, A. Z. Lugo-Aranda, R. de J. Zermeño, Sebastián F. Sánchez, Lesly Castañeda-Carlos, J. Eduardo Méndez-Delgado, K. Kreckel, Roeland P. van der Marel et al.

The Sloan Digital Sky Survey V (SDSS-V) Local Volume Mapper (LVM) is conducting an unprecedented wide-field integral field spectroscopic survey of the Milky Way, the Magellanic Clouds, and nearby galaxies using a strategy based on multiple dithered observations to achieve full spatial coverage, improved spatial sampling, and enhanced spectral depth. However, the scientific exploitation of these observations requires a robust methodology to combine the individual row-stacked spectra (RSS) into ho…

詳細を見る →

astro-ph.HEastro-ph.IM2026年8月4日

Generation of Correlated Time Series for X-ray Astronomy Applications

Seth Rowan Larner, Michael A. Nowak, Jörn Wilms

Cross-spectral methods have become essential for studying accretion physics in X-ray binaries and active galactic nuclei, where coherence and phase lag measurements constrain physical models and reveal variability components invisible in power spectra alone. Recent multi-Lorentzian fitting techniques have uncovered new quasi-periodic features through joint analysis of power spectra and cross-spectra, but testing these methods requires synthetic data with realistic statistical properties. We pres…

詳細を見る →

astro-ph.EP2026年8月4日

Orbital-Period Determination As an Indispensable Tool to Study the Pedigree of a Sungrazing Comet

Zdenek Sekanina

Among some 4500 Kreutz sungrazers known, the orbital period has been established to better than about +/-20 years only for C/1882 R1, C/1963 R1, C/1965 S1, C/2011 W3, and C/2026 A1. I describe solutions to a range of intriguing problems involving the orbital-period determination. A helpful, but computer-intensive routine is a detailed investigation of derived orbital periods as a function of the last observation used, which allows one to filter out effects of activity (the case of C/2026 A1) or…

詳細を見る →

astro-ph.IMphysics.optics2026年8月4日

CCAT: Optical Design of the 410 GHz Prime-Cam Module

Tilak M. Patel, Tanner Buck, Anthony Huber, Eve M. Vavagiakis, James Burgoyne, Scott Chapman, Ben Keller, Jenna E. Moore et al.

Prime-Cam is a first-generation instrument for the Fred Young Submillimeter Telescope (FYST), enabling wide-field, multi-frequency observations for cosmology, line-intensity mapping, and galaxy studies. We present an optical performance study for a candidate 410 GHz broadband module designed to field approximately 21,000 polarisation-sensitive kinetic inductance detectors (KIDs). The three-lens silicon design was adapted from the SO LATR design and used for the existing 280 and 350 GHz Prime-Cam…

詳細を見る →

astro-ph.EP2026年8月4日

Rotation, spectral type, and albedo of the potentially hazardous asteroid (153814) 2001 WN$_{\text 5}$ Prior to the 2028 June close approach

Jin Beniyama, Alexey V. Sergeyev, Konstantinos Odysseas Xenos, Benoit Carry, Petr Pravec, Petr Fatka, Peter Kušnírák, Larry Denneau et al.

The potentially hazardous asteroid (153814) 2001 WN$_5$ will pass inside the lunar distance on June 26, 2028, offering a rare opportunity to characterize a kilometer-scale near-Earth asteroid at high angular resolution. We aim to constrain the rotation state, shape, visible colors, geometric albedo, and taxonomy of 2001 WN$_5$ before its 2028 close approach. We combined new photometry from the 1.54 m Danish Telescope (DK154) with archival and survey observations from the Transiting Exoplanet Sur…

詳細を見る →

astro-ph.IM2026年8月4日

Foundation Models for Astrophysics

Xiaosheng Zhao, Yuan-Sen Ting

Foundation models are high-capacity networks pretrained once on broad data and then reused across many tasks. This chapter introduces them through the idea of a transferable representation, the internal description a network forms during training, which, rather than the fitted task, is what carries over to new problems. We develop the idea from first principles for an astronomical reader, starting from why a representation matters and what makes one useful, and then surveying the architectures,…

詳細を見る →

astro-ph.GAastro-ph.SR2026年8月4日

Radial abundance gradients of 18 elements in Galactic open clusters from infrared MWM spectra A detailed analysis of 655 giants in 133 clusters

S. Bijavara Seshashayana, H. Jönsson, V. D'Orazi, K. Cunha, P. Frinchaboy, J. M. Otto

Open clusters are powerful tools for studying the Milky Way. While large spectroscopic surveys now provide spectra for many cluster members, automated pipelines and heterogeneous membership selections can introduce systematics and inflate apparent cluster scatter. Therefore, a homogeneous re-analysis with careful membership control and an explicit treatment of departures from Local Thermodynamic Equilibrium is valuable for establishing robust abundance gradients. The aim is to derive precise Gal…

詳細を見る →

astro-ph.SR2026年8月4日

You're Gonna Need a Bigger Core: Calibrating Massive Star Models against Galactic OB-type Stars

Thibault Lechien, Selma E. de Mink, Stephen Justham, Abel de Burgos, Ruggero Valli, Sergio Simón-Díaz

The evolution of massive stars above 8 M$_\odot$ depends critically on the amount of mixing above the convective core during the main sequence. However, current models typically extrapolate results from lower-mass stars, where constraints from asteroseismology and eclipsing binary systems are more readily available. A new opportunity to study the evolution of massive stars and their distribution in the Hertzsprung--Russell diagram arises by combining the IACOB spectroscopic sample of over 900 Ga…

詳細を見る →

astro-ph.EPphysics.space-ph2026年8月4日

The Length of Martian Crater Rays and Their Relation to Lunar Cold Spots

Trevor P. Erwin, Brandon C. Johnson, David Minton, Alexandria V. Johnson

Impact-generated crater rays are well-documented on the Moon, with most appearing as high-albedo streaks extending radially from a crater's center. On Mars, however, crater rays are significantly rarer and discernible only through thermal imaging due to their lower thermal inertia compared to surrounding terrain. This study presents the first comparative analysis between the lengths of Martian and lunar crater rays, including lunar albedo rays and cold spots, which are ray-like thermal anomalies…

詳細を見る →

nucl-thastro-ph.HE2026年8月4日

The $g$-mode frequencies in cold neutron stars and nuclear saturation parameters

Hajime Sotani, Hajime Togashi

Oscillation frequencies excited in neutron stars are crucial for extracting their interior properties. In addition to the fundamental and pressure modes, the gravity ($g$-) modes can be excited even in zero-temperature stellar models due to the composition gradient. In this study, we systematically study the $g$-mode frequencies, focusing on the nucleonic equation of state. Then, we can derive an empirical relation for the 1st $g$-mode frequencies as a function of the stellar compactness and the…

詳細を見る →

astro-ph.SR2026年8月4日

A catalogue of high angular resolution and contrast polarimetric maps of 45 nearby AGB stars with SPHERE/ZIMPOL

Nekolgne Aymard Badolo, Eric Lagadec, Mamadou N'Diaye, Sie Zacharie Kam, Iain McDonald, Alexis Matter, Jean Koulidiati, Lyu Abe et al.

We present the largest catalogue of asymptotic giant branch (AGB) stars, 45 targets in total, observed in polarized light at high angular resolution (~ 20 milliarcsec). The main goal of the study is to detect and characterize dust shells in the close environment of nearby AGB stars. This work also aims to systematically classify the AGB star circumstellar morphologies obtained with the SPHERE instrument installed at the Very Large Telescope (VLT), thanks to its Zurich Imaging Polarimeter (ZIMPOL…

詳細を見る →

astro-ph.SRphysics.space-ph2026年8月4日

Statistical insights on the decorrelation lengths of solar wind parameters at L1 point under varying conditions

Yogesh, Aparupa Apsara Baruah, Dibyendu Chakrabarty, Kalyan Bhuyan, Aakash Gupta, Gregory G. Howes

Understanding the spatial coherence of solar wind plasma and magnetic field properties is essential for interpreting multi-spacecraft observations and for characterizing the large-scale structure of heliospheric transients. In this study, we quantify the spatial correlation of six key solar wind parameters - interplanetary magnetic field components, bulk flow speed, proton number density, and the alpha-to-proton abundance ratio - using simultaneous measurements from the ACE and Wind spacecraft a…

詳細を見る →

astro-ph.HE2026年8月3日

Magnetic rigidity reveals the PeVatron acceleration region in SS433

Jie Liao, Wancheng Xu, Lang Cui, Pak-Hin Thomas Tam, Xi Yan, Linuo Yang, Ruo-yu Liu, Liang Chen et al.

PeVatrons are cosmic accelerators capable of driving particles to petaelectronvolt (PeV) energies. Recently, microquasar jets have emerged as compelling Galactic PeVatron candidates. This is especially the case for SS 433 as its $>100$ TeV gamma-ray emission is spatially coincident with an atomic cloud. However, the exact region where PeV protons are accelerated and injected within these jets remains unresolved. Here we report, using archival, multi-frequency VLBA observations, the magnetic fiel…

詳細を見る →

astro-ph.GA2026年8月3日

XRISM Resolves the Circum-nuclear Environment of NGC 4945

Peter G. Boorman, Poshak Gandhi, Yoshihiro Ueda, Bert Vander Meulen, Kanta Fujiwara, Aoi Nakano, Johannes Buchner, Claudio Ricci et al.

Compton-thick Active Galactic Nuclei (AGN) represent one of the most elusive phases of massive black hole growth, yet are expected to contribute substantially to the Cosmic X-ray Background and the integrated growth of massive black holes. NGC 4945 is the closest Compton-thick AGN and amongst the brightest AGN in the hard X-ray sky, making it an important benchmark for more distant Compton-thick AGN. We present the first high-resolution X-ray spectral analysis of NGC 4945 using XRISM/Resolve. Th…

詳細を見る →

astro-ph.IM2026年8月3日

Spatial Mapping and Capacitor Trimming Developments to Improve Usable Pixel Yield in PRIMA FIRESS Kilo-Pixel Arrays

Chris Albert, Jonathon Hunacek, Hien Nguyen, Ritoban Basu Thakur, Andrew Beyer, Charles, Bradford, Peter Day et al.

The Probe far-Infrared Mission for Astrophysics (PRIMA) will use 8 kilo-pixel kinetic inductance detector (KID) arrays in its spectrometer module. We present an improved resonant frequency to spatial position mapping system designed to preserve each array's mapping after transferring it from the mapping apparatus to the flight housing. Such a mapping is necessary for astronomical observations, and additionally allows us to laser trim the capacitive elements of KIDs to optimize resonance separati…

詳細を見る →

astro-ph.HE2026年8月3日

Production of High Energy Neutrinos in the Coronae of Ultraluminous X-ray Sources

Norita Kawanaka, Shigeo S. Kimura

We investigate the possibility of high-energy neutrino production in coronae associated with ultraluminous X-ray sources (ULXs) as super-Eddington accreting black holes. Adopting the disk-wind-fed corona model, we calculate stochastic proton acceleration and the resulting neutrino emission from the ULX corona. We first examine whether the corona can be regarded as a collisionless plasma, which is a prerequisite for efficient non-thermal particle acceleration. We find that the collisionless condi…

詳細を見る →

astro-ph.SR2026年8月3日

Towards understanding stellar variability at the sub m/s level: granulation-induced variability across the optical spectrum

Cis Lagae, Ginger Frame, Heather M. Cegla, Veronika Witzke, René Holzreuter, Sergiy Shelyag, Christopher Watson, Alexander Shapiro et al.

Detecting the radial velocity signal of Earth-mass exoplanets requires the characterisation and removal of granulation-induced radial velocity variability from spectroscopic observations. By coupling three-dimensional (3D) hydrodynamic (HD) simulations to a radiative transfer code, we can isolate and study the effect of granulation on stellar lines. In this study we isolated the impact of granulation on spectral line shapes and shifts for the largest and most diverse synthetic spectral line samp…

詳細を見る →

astro-ph.EP2026年8月3日

Accretion across scales: streamers, surface-layer transport, and rapid replenishment in young protoplanetary discs

Christian Granzow Holm, Michiel Lambrechts, Michael Kuffmeier, Anders Johansen, Troels Haugbølle, Åke Nordlund

Protoplanetary discs evolve around newly-formed stars through an interplay of infall from surrounding turbulent cloud material, accretion towards the young star, and outflow driven mass-loss. It has been challenging to determine if discs are fed predominantly through infall along the disc midplane, or along the poles, and if accretion occurs in a steady or burst-like fashion. Here, we present a suite of 3D ideal magnetohydrodynamical simulations of protoplanetary disc formation and evolution in…

詳細を見る →

astro-ph.COastro-ph.HE2026年8月3日

A refined method for measuring cosmological distances using variability and proper motions in AGN with VLBI-detected counter-jets

Jeffrey A. Hodgson, Anthony Carr, David Parkinson, Matteo Statti, Jaehyeon Myeong, Benjamin L'Huillier, Arman Shafieloo, Ioannis Liodakis et al.

In a previous paper, we described a `standard speed-gun' (SSG) distance that uses the speed of light to standardize a ruler under the assumption that the radio variability seen in blazars is causally limited. The apparent size is then measured with Very Long Baseline Interferometry in order to derive the angular diameter distance. A key limitation of this method is that it requires knowledge of the relativistic Doppler factor. Previously, we estimated the distance to the bright radio source, 3C…

詳細を見る →

astro-ph.SRastro-ph.IMphysics.plasm-phphysics.space-ph2026年8月3日

Performance of radio-based detection to operational monitoring M5+ class solar flares

Julia van Ravenswaaij, Ines Wilms, Ivan Ricardo, Michaela Brchnelova

Early detection of major solar flares is critical for defense operations due to their potential to disturb radar and radio systems. Typically, soft X-ray flux is used to monitor and classify solar flares, but since this flux has to be measured in space, it means that its availability itself is dependent on space weather conditions. For this reason, in this paper, we investigated the feasibility of using ground radio observations to monitor major (M5+ class) solar flares. We made use of datasets…

詳細を見る →

astro-ph.IM2026年8月3日

The Wetterstein Millimeter Telescope: A New German Facility for Astronomy and Geodesy

Alexander Neidhardt, Matthias Kadler, A. K. -Baczko, Guido Dietl, Urs Hugentobler, Matthias Schartner, Tobias Ullmann, Till Rehm et al.

The Wetterstein Millimeter Telescope (WMT) is a planned broadband (1.2-120 GHz) radio telescope to be established near the Environmental Research Station Schneefernerhaus (UFS) on Germany's highest mountain, the Zugspitze. Developed by a consortium of German research institutes and partners, the WMT is conceived as a multidisciplinary research infrastructure supporting radio astronomy, geodetic VLBI, satellite communications, space situational awareness, and technology development. The telescope…

詳細を見る →

astro-ph.EP2026年8月3日

A JWST Study of Stardust. I. Infrared Spectroscopy of Comet 81P/Wild 2 and Overall Composition

Nathan X. Roth, Stefanie N. Milam, Diane H. Wooden, Charles E. Woodward, Dominique Bockelee-Morvan, Michael S. P. Kelley, Steven B. Charnley, Simon J. Clemett et al.

We report observations of comet 81P/Wild 2, target of the Stardust sample return mission, on UT 2023 March 20 and 24 at a heliocentric distance ($r_H$) of 1.85 au using the NIRSpec and MIRI integral field unit spectrographs on board the James Webb Space Telescope (JWST). This study is the first compositional comparison between JWST remote-sensing spectroscopy of a solar system object against terrestrial analysis of its returned samples. We securely detected molecular emission from H$_2$O, CH$_4$…

詳細を見る →