研究動向

astro-ph.HEastro-ph.SR2026年7月28日

A radio view on Gamma-Loud Protostars: Derivation of jet mechanical luminosity

Javier Méndez-Gallego, Carlos Carrasco-González, Rubén López-Coto, Iván Agudo, Stefano Menchiari, Rubén Fedriani, Emma de Oña Wilhelmi, Guillem Anglada et al.

Context. Gamma-Loud Protostars (GLPs) have been recently reported as Galactic hadronic accelerators whose acceleration site is situated in their protostellar jets. Theoretical and observational analysis situate radio cm luminosity as a thermal tracer of jet activity, presenting an unique opportunity to study jet properties as accelerators. Aims. We aim to develop a way to estimate the kinetic power of protostellar jets and compare their energetics with those extracted from the non-thermal gamma-…

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astro-ph.GA2026年7月28日

Observational Tests of Sgr A*'s State of the Accretion Flow

F. Yusef-Zadeh, R. G. Arendt, H. Bushouse, C. J. Chandler, D. Kunneriath, S. M. Ressler, M. Wardle

General relativistic magneto-hydrodynamic (GRMHD) simulations of the possibly magnetically arrested disk (MAD) of the accretion flow of Sgr A* predict short and long time variability, lumpiness in the flow, strong magnetic fields, reconnection driving flux eruptions and a jet aligned with its spin angular momentum. We carried out simultaneous multi-wavelength observations with the objective of placing some constraints on these predictions. Our analysis supports most of the predictions of the MAD…

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gr-qcastro-ph.HEastro-ph.IMcs.LG2026年7月28日

Fast, accurate, and differentiable: a neural-network surrogate for NRSur7dq4 precessing binary black hole waveforms

Michael Pürrer, Ashwin Girish, Lucy M. Thomas, Scott E. Field, Vijay Varma

We present a neural network surrogate model that emulates the NRSur7dq4 gravitational waveform model for precessing binary black hole mergers. The surrogate decomposes the waveform into constituent quantities and trains an independent multilayer perceptron (MLP) for each. We validate the surrogate against NRSur7dq4 on 10,000 waveforms spanning its full parameter space ($1 \leq q \leq 4$, $|χ_{A,B}| \leq 0.8$). For representative total masses between 60 and 300 $M_\odot$, median sky-averaged freq…

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astro-ph.SR2026年7月28日

Empirical H- and K-band Limb Darkening for 31 CHARA Stars: A Near-Infrared Benchmark for Stellar-Atmosphere Models

Narsireddy Anugu, John D. Monnier, Antoine Mérand, Becky Flores, Alexandre Gallenne, Douglas R. Gies, Mayra Gutierrez, Robert Klement et al.

Limb darkening, the decrease in stellar intensity from the disk center to the limb, encodes the temperature structure and opacity of stellar atmospheres. Direct spatially resolved measurements of this center-to-limb variation remain scarce, especially in the near-infrared. We present interferometric limb-darkening measurements for 31 stars observed simultaneously in the $H$ and $K$ bands with the CHARA Array. The sample spans spectral types F--M and luminosity classes IV--I. The targets are well…

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astro-ph.HE2026年7月28日

Simulation of combined radio and radar signals at the Radar Echo Telescope for Cosmic Rays

K. Nivedita, I. Loudon, J. Loonen, P. Allison, J. J. Beatty, D. Z. Besson, A. Connolly, A. Cummings et al.

To explore neutrino astronomy at high energies (> 10 PeV), the Radar Echo Telescope for Cosmic Rays (RET-CR) was developed to assess the feasibility of a radar technique for detecting particle cascades in ice, serving as a precursor to the Radar Echo Telescope for Neutrinos (RET-N). The main concept of RET-CR is that, as a high-energy cosmic-ray air-shower core propagates into the high-altitude ice sheet, a dense secondary-particle cascade is created, which is very similar to that of an in-ice h…

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astro-ph.GAastro-ph.CO2026年7月28日

Reaching the Metallicity Floor at $z\sim 10$: Lensed Star Clusters at Cosmic Dawn and Cosmic Noon

Raul Jimenez, Elena Tomasetti, Carmela Lardo, Licia Verde

Origins of globular clusters (GCs) are linked to the assembly of their host galaxies. We analyze star-cluster populations in two strongly lensed systems that bracket Cosmic Dawn and Cosmic Noon: the Cosmic Gems arc (GEMS) at z=9.625, among the first galaxies, and the Sparkler at z=1.378. New STARRED deconvolution photometry of GEMS provides SEDs for ten unique, doubly imaged cluster candidates, while a homogeneous Bayesian analysis places both populations on a common cosmological timeline. The G…

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astro-ph.HEastro-ph.SRgr-qc2026年7月28日

Gravitational Wave Modeling of White-Dwarf--Compact-Object Binaries and Observational Outlook

Tristan S. Weaver, David Radice, Donghui Jeong, Victor Liu

We investigate the end stages of circular white-dwarf--compact-object binaries by developing a novel integrator implementing mass transfer and 2.5-order Post-Newtonian kinematics. White-dwarf--compact-object binaries are subject to two phases: a slow inspiral during which binary evolution is dominated by weak-gravity radiation reaction and a quicker ``outspiral" dominated by mass transfer. These systems have unique gravitational waveforms with several characteristic features including an accumul…

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astro-ph.SR2026年7月28日

A Test of FeH Line Parameters using DR19 APOGEE spectra of Benchmark M Dwarfs

Anderson Silva-Andrade, Diogo Souto, Katia Cunha, Verne V. Smith, Carlos Allende Prieto, Ricardo P. Schiavon, Verónica Loaiza-Tacuri, Aida Behmard et al.

Recent studies have suggested a mismatch of up to 0.20 dex between iron abundances derived from Fe I and FeH lines in the H-band spectra of M dwarfs, and in this work we investigate the nature of this possible offset. We analyze near-infrared H-band APOGEE spectra of stars in 18 binaries composed of a G-dwarf primary and an M-dwarf secondary, together with four M-dwarf stars having measured angular diameters from the literature, and six M-dwarf members of the Hyades and Coma Berenices open clust…

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cs.LGastro-ph.GAcs.AIstat.ML2026年7月28日

Multiclass Classification without Labels via Posterior Simplex Geometry

Raphaël Bonnet-Guerrini, Johann Ioannou-Nikolaides, Troels Petersen, Vincenzo Piuri

In many classification problems, reliable instance-level labels are unavailable. However, it is often possible to construct weakly enriched unlabeled samples: datasets selected by different cuts, sources, populations, or experimental conditions that change latent class proportions without revealing them. Classification without Labels (CWoLa) shows that, in the binary case ($K=2$), a classifier trained to distinguish two impure mixtures with different class proportions can recover an optimal clas…

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astro-ph.SRastro-ph.GA2026年7月28日

Investigating the Observational Progenitor Mass Gap in the White Dwarf Initial-Final Mass Relation. I. Cluster Census and Characterization of the First White Dwarfs in the Gap

David R. Miller, Jeremy Heyl, Pier-Emmanuel Tremblay

In recent years, Gaia has been the primary driver of the expansion of the white dwarf (WD) initial-final mass relation (IFMR) in open clusters. The increased sample size has highlighted a pronounced observational gap at progenitor masses of $\simeq2$--$2.7\,M_\odot$, with no spectroscopically confirmed cluster-member WDs in this range. Analysis of the Milky Way open cluster census shows that this absence is primarily driven by the scarcity of appropriately aged, nearby clusters capable of hostin…

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gr-qcastro-ph.HE2026年7月28日

Tidal deformation of an accreting compact object

Avijit Chowdhury, Chiranjeeb Singha, Kazuharu Bamba, Sumanta Chakraborty

Tidal deformation of a compact object serves as a sensitive probe of the strong-gravity regime and nature of the compact object. It captures how a compact object responds to the external perturbing field of a companion. In realistic astrophysical settings, compact objects are typically immersed in matter-rich environments, which can significantly alter the response. In this work, we investigate the static deformability of Schwarzschild-like exotic compact objects (ECOs) embedded in a quasi-stati…

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astro-ph.GA2026年7月28日

Using Scattered Near-Infrared Light to Map Water Ice in Prestellar Cores with SPHEREx

Tamojeet Roychowdhury, Jennifer B. Bergner, Jens Kauffmann, Thushara G. S. Pillai, Silvia Spezzano

We present the first coreshine-derived, spatially-resolved maps of the 3 $μ$m H$_2$O ice absorption feature in four prestellar cores, using SPHEREx spectra. Ices are a key component of dense cores in molecular clouds, playing a central role in the chemistry of planet formation around young stars. However, spatially resolved abundance studies remain limited, typically relying on unevenly distributed background star sightlines. Here, we take advantage of the all-sky spectrophotometric capabilities…

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astro-ph.GAastro-ph.HE2026年7月28日

S301 and friends: Measuring the spin of Sgr A*

T. Piran, P. Amaro-Seoane, B. Aytac, G. Bourdarot, A. Burkert, D. Calderon, J. Cuadra, F. Eisenhauer et al.

The discovery of S301 (GRAVITY Collaboration et al., 2026) with pericenter distance rp= 280rg and eccentricity e=0.9825, opens the prospect of measuring the spin parameter of Sgr A* through Lense--Thirring (LT) nodal precession. A major obstacle is Newtonian confusion: any non-spherical extended mass distribution can also induce nodal precession. We aim to separate the LT spin signal of S301 from the Newtonian nodal precession. We compare the secular Newtonian torque exerted by a disk or flatten…

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astro-ph.GA2026年7月28日

Observational Evidence for Anisotropic Metal Excess around Galaxies

Cheqiu Lyu, Enci Wang, Zeyu Chen, Chengyu Ma, Yangyao Chen, Haoran Yu, Xu Kong

The exchange of matter and energy between galaxies and their surroundings drives the cosmic baryon cycle, yet mapping metal transport remains an observational challenge. While simulations predict that galactic winds escape anisotropically along minor axes, evidence for chemical enrichment in neighboring galaxies is limited. We analyze 1,433 galaxy pairs from the Dark Energy Spectroscopic Instrument survey and detect a gas-phase metallicity excess of 14.6% $\pm$ 3.7% to 24.2% $\pm$ 2.6% in neighb…

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astro-ph.SRastro-ph.IM2026年7月28日

Syntriod: A Robust Initial Parameter Estimator for Radial Velocity Curve Solutions Beyond Conventional Sampling Limits

Emre Barbaros, Hasan Ak, N. Filiz Ak

We present Syntriod, an orbital-phase domain radial velocity (RV) template-based algorithm designed to provide robust initial orbital parameter estimates for spectroscopic binaries across diverse observational sampling conditions. Rather than performing full orbital inference, Syntriod constrains the parameter space with physically consistent solutions to guide subsequent optimization procedures. We evaluate its performance using 10,000 synthetic Keplerian orbits spanning diverse configurations…

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astro-ph.COastro-ph.GAastro-ph.IM2026年7月28日

Interlopers as Signal in Line Intensity Mapping

Anirban Roy

Line intensity mapping measures the combined emission of atomic and molecular lines from unresolved galaxies, offering a way to map cosmic structure across enormous volumes. A single observed frequency, however, contains emission from several spectral lines at different redshifts. These interlopers are usually removed before cosmological inference. We show that this removal is not always optimal. Once the possible emitting lines and their redshifts are included in the model, interlopers become a…

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astro-ph.GAastro-ph.HE2026年7月28日

Vigorous turbulence driven by quasar-mode feedback in a cluster core

Satoshi Yamada, Shutaro Ueda, Hirofumi Noda, Yutaka Fujita, Misaki Mizumoto, Kentaro Nagamine, Claudio Ricci, Shoji Ogawa et al.

Quasars are among the most luminous objects. They are powered by accretion onto supermassive black holes. They are thought to impact cosmological evolution primarily through energetic winds, known as quasar-mode feedback, yet the efficiency and spatial extent of this process remain poorly constrained. Here we present X-Ray Imaging and Spectroscopy Mission (XRISM) observations of H1821+643---the nearest galaxy cluster with a central quasar (redshift z = 0.297)---which was a rare opportunity to di…

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astro-ph.IMphysics.optics2026年7月28日

Demonstrating the integration of a photonic lantern with an all-fiber-based nulling interferometer

Jordan Diaz, Rebecca Jensen-Clem, Philip M. Hinz, Daren Dillon, Pradip Gatkine, Aditya R. Sengupta, Dan Sirbu, Sarah Tedder et al.

High-contrast imaging of Solar System scale exoplanets and protoplanets demands advancements in instrumentation to access deeper starlight suppression at smaller angular separations than today's state-of-the-art. The multi-mode to single-mode conversion capabilities of photonic lanterns (PLs) provide new avenues to implement techniques such as nulling interferometry due to the inherent spatial filtering of single-mode waveguides. In this work, we present laboratory results on an all-fiber-based…

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astro-ph.EP2026年7月28日

Atmospheric Escape Rates of Planets in Stellar Tidal Fields from 3-D Hydrodynamic Simulations

Ritika Sethi, Morgan MacLeod, Sarah Millholland

Thermally driven atmospheric escape, including photo-evaporation and core-powered mass-loss, plays a key role in shaping the evolution of close-in exoplanets, yet most current models rely on simplified one-dimensional descriptions of atmospheric escape. In this work, we perform 3D hydrodynamic simulations of atmospheric outflows from a Jupiter-sized planet embedded in the gravitational potential of a solar-type host star, and compare these results with 1D models to identify the regimes where the…

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astro-ph.SR2026年7月28日

Supergranulation as a Tracer of Solar-Cycle Variability

Irina N. Kitiashvili, Andrew A. Ngo, Spiridon Kasapis

Supergranulation is one of the dominant scales of near-surface solar convection and provides an important diagnostic for studying the interaction between convective flows, rotation, and magnetic activity. We develop an automated framework to identify and characterize supergranular structures using subsurface horizontal-velocity maps inferred from time-distance helioseismology. The method applies Laplacian-of-Gaussian detection to horizontal velocity divergence maps and combines this with magneti…

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astro-ph.GA2026年7月28日

CHORD HI-Galaxy Survey Forecasts: Searching for nearby dark galaxies and high redshift giants

Akanksha Bij, Kristine Spekkens, Hans S. Hopkins, Michael G. Jones, Arnab Chakraborty, Simon Foreman, Alex S. Hill, Dustin Lang et al.

Population studies of gas-rich galaxies across the full range of Neutral Hydrogen (HI) masses that galaxies are known to exhibit ($10^5 \lesssim M_{\mathrm{HI}} \lesssim 10^{11} M_{\odot}$) remain limited by the need to conduct high-sensitivity, wide-band surveys across significant sky areas. The Canadian Hydrogen Observatory and Radio-transient Detector (CHORD) is a next-generation radio telescope that will significantly expand the census of HI-galaxies to date from untargeted drift-scan survey…

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astro-ph.GA2026年7月28日

When galaxies cross cold fronts: wind tunnel simulations of ram pressure stripping

Elvis A. Mello-Terencio, Rubens E. G. Machado, Richards P. Albuquerque

Cluster collisions and mergers are among the most energetic phenomena in the low redshift Universe. These interactions disturb the intracluster medium creating regions with density and temperature discontinuities, such as sloshing spirals. There is evidence that such environments can influence galaxy evolution. This study aims to understand how a galaxy that crosses an environment with discontinuities in density and temperature can be affected. To this end, a set of simulations was conducted usi…

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astro-ph.GA2026年7月28日

Too many quiescent late-type galaxies or a matter of misclassification?

J. L. Tous, S. I. Raimundo, H. Domínguez Sánchez

In the local Universe, the terms late-type and early-type are used to describe, respectively, disc galaxies with spiral arms and more bulge-dominated systems lacking spiral structure. These morphologies are often associated with different star formation levels, motivating the classical scenario where late-type and early-type galaxies are seen, respectively, as star-forming and "red and dead" systems. To build a comprehensive picture of galaxy evolution, we must understand the relationship betwee…

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astro-ph.GA2026年7月28日

Laboratory spectroscopy, theoretical characterization, and astronomical search for syn-propenethial (CH2CHCHS)

Germán Molpeceres, Carlos Cabezas, Marcelino Agúndez, María Mallo, Yasuki Endo, Lucie Kolesniková, Gisela Esplugues, José Cernicharo et al.

We report the laboratory characterization of the higher-energy isomer of propenethial, syn-CH2CHCHS. While the lower-energy isomer, anti-CH2CHCHS, was detected in the interstellar medium during the QUIJOTE line survey of TMC-1, we report the non-detection of the syn isomer in the same source, deriving an upper limit to its column density of 1.5 $\times$ 10$^{10}$ cm$^{-2}$. A subsequent theoretical investigation into the origin of this non-detection reveals that the most plausible formation path…

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astro-ph.GAastro-ph.SR2026年7月28日

Stellar Dynamics and Evolution of the Intermediate-Age Open Clusters NGC 2266 and NGC 2324

Cyrus Raj, D. Bisht, Ashish Raj

We present a refined astrometric and photometric analysis of the well-studied intermediate-age open clusters NGC 2266 and NGC 2324 using high-precision Gaia DR3 data, complemented by 2MASS and LAMOST DR7 catalogs. Probable cluster members are identified using unsupervised machine learning techniques. We apply both Gaussian Mixture Models (GMMs) and \texttt{pyUPMASK}. We find that the GMM-based membership sample yields a cleaner, more coherent cluster sequence in the Gaia CMDs than pyUPMASK. We i…

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astro-ph.IM2026年7月28日

Map Multi-Tool: A Map-Based Approach to Modeling Beam Systematics for Cosmic Microwave Background Experiments

Cesiley L. King, Alec Hryciuk, Jeff McMahon, Johanna M. Nagy, John E. Ruhl

Cosmic microwave background (CMB) experiments use simulations of instrumental systematic effects to ensure high-fidelity measurements of cosmological parameters. Quantifying the expected magnitude of these effects enables experiments to improve designs, set performance requirements, and understand potential measurement biases from residual systematics. Here we present a new simulation framework, called Map Multi-Tool (MMT), which models beam-related systematics for CMB instruments using a map-ba…

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astro-ph.GAastro-ph.SR2026年7月28日

Constraining young massive cluster properties with radio-continuum observations: The Arches cluster

M. Cano-González, R. Schödel, A. Alberdi, F. Najarro, J. Moldón, M. Pérez-Torres, F. Nogueras-Lara

The Arches cluster, located in the Galactic Centre (GC) is one of the best astrophysical laboratories to study the properties of massive stars and young massive clusters (YMCs). However, several fundamental parameters of the Arches cluster remain uncertain. Our goal is to constrain key cluster parameters (cluster age, mass, and initial mass function, IMF) by comparing the observed stellar radio flux density distribution of the Arches cluster to those derived from a set of synthetic clusters. We…

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astro-ph.IM2026年7月28日

Shack-Hartmann wavefront sensor slope measurement algorithm robust to scintillation and sensor saturation

Timoth{é}e Vene, Laurent M Mugnier, Aur{é}lie Montmerle-Bonnefois, Jean-Marc Conan

High throughput optical communication links require the use of adaptive optics (AO) to compensate for atmospheric turbulence even in strong perturbation conditions and at low elevation. Considering the intensity fluctuations brought by scintillation, we present a new slope measurement algorithm for the Shack--Hartmann wavefront sensor (SHWFS), based on a joint maximum likelihood approach. We show that this estimator is robust to sensor saturation and widens by more than two orders of magnitude t…

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astro-ph.IM2026年7月28日

The Wide-field Spectroscopic Telescope (WST): design trade-offs for the low-resolution multi-object spectrograph instrument

Dimitri Buffat, Will Saunders, Kjetil Dohlen, Laurence Tresse, David Lee, Roland Bacon, Andrea Bianco, Laurane Fréour et al.

The Wide-field Spectroscopic Telescope (WST) is a planned 12-meter-class dedicated spectroscopic facility designed to address key scientific challenges through large spectroscopic surveys. This paper presents design and performance trade-offs for the Low-Resolution Multi-Object Spectrograph (MOS-LR) instrument. With a multiplex of 30,000 covering a field of view of 3.1 square degrees, this instrument will provide unprecedented survey efficiency, an order of magnitude beyond those of current faci…

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astro-ph.EPastro-ph.IM2026年7月28日

Disk-averaged spectrum generation for spherically symmetric planets and moons

Nicholas A. Teanby

Here I present a simple and efficient method for generating a disk-averaged planetary spectrum. The technique uses a weighted average of component spectra generated on an irregular grid of offsets from the planet center. This accounts for variations in center to limb brightness and emission from beyond the limb, which is important for bodies with extended atmospheres such as Saturn's moon Titan. The method assumes spherically symmetric emission and requires a grid of component spectra fine enoug…

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