研究動向

astro-ph.HE2026年7月25日

Diverse Morphologies of GRB X-Ray Plateaus within a Common Magnetar Framework

Xiao-Fei Dong, Yong-Feng Huang, Nurimangul Nurmamat, Chen Deng, Ze-Cheng Zou, Fan Xu, Abdusattar Kurban, Chen Du et al.

The origin of the X-ray plateau phase in gamma-ray bursts (GRBs) remains an open problem. In particular, it is unclear whether GRBs with different temporal morphologies (i.e., with a rising, flat, or decaying plateau) arise from a common underlying mechanism. Although magnetar energy injection is a leading explanation, previous studies have primarily inferred magnetar properties on a burst-by-burst basis and have not tested the model at the population level. Here we perform the first hierarchica…

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astro-ph.HEastro-ph.CO2026年7月25日

Constraining cosmological parameters from very-high-energy $γ$-ray attenuation in blazar spectra: Bayesian inference and systematic uncertainties

Patryk Liniewicz, Emmanuel Moulin

Very-high-energy $γ$ rays from active galactic nuclei are attenuated through pair production on the extragalactic background light (EBL), providing a probe of cosmic expansion. We develop a Bayesian inference analysis framework that uses an observationally driven, redshift-dependent EBL model and anchors intrinsic source spectra to the Fermi-LAT 3FHL catalogue while marginalising spectral-shape departures and dataset normalisations. The method is validated on realistic mock observations and appl…

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astro-ph.IMphysics.ins-det2026年7月25日

Output-Stage Design Optimization for High-Sensitivity SiSeRO CCDs and SiSeRO Active Pixel Sensors

Tanmoy Chattopadhyay, Sven Herrmann, Kevan Donlon, Ilya Prigozhin, Peter Orel, Steven W. Allen, Marshall W. Bautz, Michael Cooper et al.

The Single electron Sensitive Read Out (SiSeRO) technology is a new device class designed to support the needs of future X-ray and optical astronomical telescopes that will require fast, low-noise, megapixel spectro-imagers. Developed at MIT Lincoln Laboratory, in collaboration with Stanford University and MIT, the first generation SiSeRO-CCD (charge-coupled device) prototypes achieved a charge/current conversion gain of 700$-$800 pA per electron, an equivalent noise charge (ENC) of around 3.5 e…

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astro-ph.GA2026年7月25日

HETDEX: Star Formation Stochasticity Diagram of Lyman Alpha Emitting Galaxies at Cosmic Noon Confirms Three Archetypes

Nicole Firestone, Eric Gawiser, Kartheik G. Iyer, Charlotte Olsen, Antara Basu-Zych, Adam Broussard, Peter Kurczynski, Kyoung-Soo Lee et al.

In this work, we aim to measure the star formation stochasticity of Lyman Alpha Emitting Galaxies (LAEs) at Cosmic Noon. We identify 270 LAEs from the HETDEX Survey in the COSMOS field with rest-UV-through-NIR photometry from CANDELS\null. For each LAE, we perform non-parametric gaussian-process star formation history (SFH) reconstruction using the Dense Basis method. Our HETDEX LAE sample is described well by the three SFH archetypes defined for ODIN LAEs in Firestone et al. 2025 with comparabl…

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astro-ph.SR2026年7月25日

High-resolution spectroscopy of the bipolar proto-planetary nebula Hen 3-1475, the Garden Sprinkler Nebula

Ana Valeria Beltrán-Sánchez, Miriam Peña, Mudumba Parthasarathy

A detailed analysis of high-resolution spectra in the optical and near-infrared range of the central zone of the proto-planetary nebula Hen 3-1475, obtained in 2006 and 2024, is conducted. The spectrum primarily revealed stellar emission of H Balmer and Paschen series, lines of iron (Fe I, Fe II, and [Fe II]), and other significant lines of He I, Ca II, [Ca II], and O I. Several multiplets of Fe II, the H Balmer series, Ca II H and K, Na I D and He I lines exhibit P-Cygni profiles and bump-like…

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astro-ph.EPastro-ph.SR2026年7月25日

Asymmetrical shape of the Near-Infrared K 4p-5s doublet perturbed by He and H2

N. F. Allard, J. F. Kielkopf

The goal of this paper is to provide an exhaustive study of the K 4p-5s doublet at 1.243/1.252~$μ$m perturbed by He and H$_2$ in physical conditions of brown dwarfs. This work is applicable to analysis of the ESO SupJup Survey's J-band spectra such as for Luhman~16. Line profiles of this doublet computed within a unified line-shape theory exhibit a blue asymmetrical behavior. This effect is of increasing importance with He and H2 density, and as a result, the full treatment of the infrared K dou…

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physics.space-phastro-ph.IMastro-ph.SR2026年7月25日

For SIRs, CIRs, and Beyond: Polarization Ratio to Feature Location

Curt A. de Koning, Dusan Odstrcil, Sarah Gibson, Craig DeForest, Vic Pizzo, Christopher J. Scott

The Polarimeter to UNify the Corona and Heliosphere (PUNCH) mission will remotely observe solar wind transients with high signal-to-noise ratio, high-cadence, high-resolution polarized white-light images. Using different polarization states, an important PUNCH data product will be polarization ratio images. In the small-Sun limit, and using two simple line-of-sight density distributions with a finite angular width that can approximate a stream or corotating interaction region (SIR/CIR), we analy…

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astro-ph.EP2026年7月25日

Metal-Silicate Segregation During Planetary Accretion: Limited Iron Emulsification through intermediate Impacts

L. Honarbakhsh, G. Morra, P. Mora, CRM. Jackson

In this study, we investigate the post-collisional evolution of an impactor's iron core within a fully molten magma ocean using 2D numerical simulations with a novel Rothmann-Keller multiphase Lattice Boltzmann Method. The impactor's core diameter ranges from $152\;\text{km}$ to $552\;\text{km}$, with aspect ratios from $0.75$ to $5$. At Reynolds numbers up to $10^4$, our models reveal significant deformation and progressive fragmentation of the impactor into an iron cloud down to the smallest s…

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astro-ph.GA2026年7月25日

PhotoIFU: NIRCam as a Photometric Integral Field Unit for Mapping Feedback in Galaxies

Yongda Zhu, Marcia J. Rieke, Courtney Carreira, Yang Sun, Zhiyuan Ji, Jianwei Lyu, Christina C. Williams, Stacey Alberts et al.

We present PhotoIFU, a workflow that uses deep multi-band imaging as a low-resolution photometric integral field unit. Applied to PSF-matched JWST/NIRCam imaging, PhotoIFU treats each spatial pixel as a coarse SED element and fits the pixel SEDs with Prospector to map resolved stellar-population and ISM-related properties. We apply this approach to three galaxies at $z=1.3$--3.7 in JADES: two systems with extended ionized line emission and one post-starburst galaxy with an exceptionally strong n…

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stat.MLcs.LGphysics.space-phstat.ME2026年7月25日

Covariance-Boosted Gaussian Processes for Spatiotemporal Irregularities

Jeremy Ovadia

Nonstationary Gaussian process (GP) models are powerful tools for capturing input-dependent variability by adapting to observed data. However, with limited sampling and highly parameterized covariance structure, they are often prone to overfitting and overconfident uncertainty estimates, potentially leading to misleading predictions in safety-critical applications. Motivated by ionospheric modeling for satellite-based augmentation systems (SBAS), this paper proposes a Covariance-Boosted Gaussian…

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eess.SYastro-ph.EPastro-ph.IMmath-ph2026年7月25日

Drift-Aware Multi-Target Space Tug Logistics Using Natural Orbital Precession

Omer Burak Iskender, Leonard Felicetti, Kaan Gokturk, David Tellett, Adam Baker

Multi-rendezvous missions for active debris removal and in-orbit servicing incur prohibitive propellant costs when their targets differ in the orientation of their orbital planes, and classical mission design treats the nodal precession induced by Earth's oblateness as a perturbation to be cancelled. This paper presents a drift-aware trajectory optimisation framework that instead exploits that precession as a mission-design resource, benchmarked against the published winning solution to the Euro…

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astro-ph.GA2026年7月25日

A quasar hatching from a buried red phase at z = 3.7

Zheng Ma, Yongda Zhu, Zhiyuan Ji, Eiichi Egami, Marcia J. Rieke, Xiaohui Fan, Jianwei Lyu, George H. Rieke et al.

We present JADES-GS 209777, previously cataloged as CANDELS J033238.02-274626.2, hereafter "the Hatchling," a red quasar at $z=3.711$. While the source has been reported in earlier deep-field catalogs, our multiwavelength analysis reveals a visible active nucleus still embedded in a dense gas- and dust-rich environment. Red quasar continua are often attributed to dust attenuation, including non-standard extinction curves, but the highly comprehensive multiwavelength data for this source provide…

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astro-ph.IM2026年7月25日

SuperFIRE: Concept evolution of a seeing-limited broadband spectrograph for the GMT

Gustav M. Pettersson, Gábor Fűrész, Nathan P. Lourie, F. Elio Angile, Jill Juneau, Gerardo Berlanga Molina, Robert A. Simcoe

We are developing the SuperFIRE concept, which builds on the heritage of the FIRE spectrograph at Magellan, as a broadband (about 340 nm to 2.5 um) intermediate resolution (R=10,000) single-shot natural seeing spectrograph for the Giant Magellan Telescope (GMT) with support from the Kavli Foundation. This single-object spectrograph is envisioned as a first-light instrument that can operate in natural seeing and grow in long-term capability as the telescope and adaptive optics systems mature. Her…

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astro-ph.EPastro-ph.SR2026年7月25日

Tracing outer planetary systems through white dwarf pollution in wide binaries

Carolina Lizana-Vidal, Claudia Aguilera-Gómez, Laura K. Rogers, Amy Bonsor, María Ignacia Muñoz-Arriagada, Patrick Dufour, Constanza Bravo-Parra, Ema Salugova et al.

White dwarf (WD) atmospheric metal pollution provides strong evidence for the presence of remnant planetary material and it can be used as an indirect tracer of outer planetary systems. We analyze whether the presence of a wide stellar companion affects the occurrence of outer planetary systems by comparing the incidence of calcium (Ca) pollution in hydrogen-atmosphere WDs in wide binaries and in apparently single stars. We construct two sample pairs: a large homogeneous SDSS low-resolution spec…

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astro-ph.EPastro-ph.GAastro-ph.SR2026年7月25日

The JDISC Survey: Inner Disk Chemistry of Class I/FS Disks and Tentative Evidence for Early Pebble Drift

Ke Zhang, Andrea Banzatti, Colette Salyk, Abygail Waggoner, Klaus Pontoppidan, María José Colmenares, Ilaria Pascucci, Lucas A. Cieza et al.

We present the first chemical survey of Class I and Flat-Spectrum (I/FS) disks using JWST MIRI/MRS, targeting sixteen sources in the Ophiuchus star-forming region. Through empirical line luminosity measurements and multi-component slab modeling, we characterize the molecular reservoir of these young systems and compare them to twelve Class II disks of similar stellar mass. Water, HCN, C$_2$H$_2$, and CO$_2$ are frequently detected in I/FS sources with inclinations $i < 70^{\circ}$, whereas edge-…

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astro-ph.GA2026年7月25日

The role of filaments in the large-scale conformity signal

Daniela Palma, Ivan Lacerna, Noelia Pérez, Luis Pereyra, Antonio D. Montero-Dorta, Constanza A. Soto-Suárez, Laerte Sodré, M. Celeste Artale et al.

We investigate the large-scale conformity signal and its connection with the large-scale structure, focusing on low-mass central galaxies, after excluding galaxies that were satellites in the past. We measure the signal across different environments identified with the DisPerSE algorithm, including group outskirts, cluster outskirts, filaments, filament outskirts, and other environments (voids and walls) in order to assess how each population contributes to the large-scale conformity signal. We…

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astro-ph.SR2026年7月25日

1000 cataclysmic variables identified from DESI spectroscopy

K. Inight, B. T. Gänsicke, A. Aungwerojwit, P. Izquierdo, C. J. Manser, A. D. Myers, A. Swan, J. R. Thorstensen et al.

Most cataclysmic variables (CVs) are discovered when they have an outburst generating an inherent selection bias against CVs that rarely, or never, outburst. CVs discovered by virtue of their spectroscopic characteristics are particularly valuable to offset this bias and we have used an established machine-learning technique to assist in searching 98 966 000 spectra obtained by the Dark Energy Spectroscopic Survey (DESI) to find such CVs. DESI observations are much deeper than previous spectrosc…

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astro-ph.GAastro-ph.IM2026年7月25日

Unsupervised selection and characterisation of Little Red Dots in JWST surveys with manifold learning

Michele Ginolfi, Filippo Mannucci, Alessandro Marconi, Francesco D'Eugenio, Giacomo Venturi, Francesco Belfiore, Giovanni Cresci, Caterina Bracci et al.

Little Red Dots (LRDs) are compact, red sources discovered at high redshift by JWST whose physical nature and selection function remain debated. We investigate whether an unsupervised machine-learning approach applied to multi-band photometry can identify LRD-like objects, and other populations, without relying on predefined colour cuts. Using UMAP, a manifold-learning (dimensionality-reduction) method, we place ~242,000 isolated, well-measured sources from the ASTRODEEP-JWST catalogue on a two-…

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astro-ph.GA2026年7月25日

Reionization driven by the few: the ionizing budget of galaxies at z=5-10 from JWST/NIRSpec

Emma Giovinazzo, Pascal A. Oesch, Anne Verhamme, Romain A. Meyer, Callum Witten, John Chisholm, Rui Marques-Chaves, Charlotte Simmonds et al.

The sources responsible for the Epoch of Reionization (EoR), the last major phase transition of the Universe, remain highly elusive. While JWST has begun to illuminate the properties of early galaxies, the direct detection of their ionizing photons is virtually impossible due to the neutral intergalactic medium (IGM) at z>6. A direct estimate of the escape fraction of ionizing photons (fesc) is thus not possible. However, the escape fraction is encoded in spectral features that trace a low opaci…

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astro-ph.SRastro-ph.GAastro-ph.IM2026年7月25日

BOSS-CLAM: Utilizing a Constrained Linear Absorption Model to Infer Stellar Parameters from BOSS Spectra

Ilija Medan, Andrew R. Casey, Alexander P. Ji, Jonah M. Otto, Kayvon Sharifi, Zachary Way, Madeleine McKenzie, Natalie R. Myers et al.

Large spectroscopic surveys require robust pipelines capable of inferring stellar parameters over a wide range of the Hertzsprung-Russell (HR) diagram from data of varying quality. SDSS-V is one such survey, where the data from the lower-resolution, optical BOSS spectrograph will provide a large dataset covering a wide range of Galactic stellar populations. To better analyze these data, we present BOSS-CLAM, a generative, forward modeling pipeline for inferring effective temperature ($T_\mathrm{…

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astro-ph.EP2026年7月25日

SCoRE: the Surface Composition of Rocky Exoplanets

Leon Sereinig, Oliver Herbort

Context. The crust composition of rocky exoplanets with a substantial atmosphere can not be observed directly. However, recent developments are starting to allow for the observation and characterisation of their atmospheres. Understanding the link between atmospheres and crusts could allow for constraints on the crusts' composition based on atmospheric observations. Aims. We aim to understand the link between the thermal stability of specific condensates and atmospheric compositions. This allows…

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astro-ph.COastro-ph.HEhep-phphysics.plasm-ph2026年7月25日

Relativistic Chiral MHD with application to the early Universe

Deepen Garg, Jennifer Schober

We present a systematic derivation of the equations of relativistic chiral magnetohydrodynamics (MHD) for a plasma of charged fermions in an expanding universe. Through a combination of a coordinate transformation and a rescaling of the dynamical variables, we bring the full system to the same form as in the Minkowski metric, with the Hubble expansion surviving only in the chirality-flipping rate and the kinematic viscosity. Retaining all four contributions to both the electric and the axial cur…

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astro-ph.COastro-ph.HEphysics.plasm-ph2026年7月25日

A charge-flow instability in plasmas with charge fluctuations

Deepen Garg, Jennifer Schober

We present a linear instability in magnetized plasmas with charge fluctuations. It is driven by an electric current proportional to the charge chemical potential $μ$ and the bulk velocity. This charge-flow (C-flow) instability has hitherto not been considered in standard magnetohydrodynamics or its chiral extensions. We derive its dispersion relation and maximum growth rate, and confirm them with direct numerical simulations. We also show that the C-flow instability persists even for zero-mean f…

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astro-ph.GAastro-ph.HEastro-ph.SR2026年7月25日

Charting the Galactic Underworld I: Comprehensive simulations of the kinematics, rates, and demographics of Milky Way black holes

Tom Wagg, Katelyn Breivik, Adrian M. Price-Whelan, Mathieu Renzo, Julianne J. Dalcanton, Natasha S. Abrams

With upcoming data from Roman, Gaia DR4, and spectroscopic surveys, we will soon have an unprecedented dataset of Milky Way black holes (BHs) to constrain their formation and evolution. To prepare, we simulate the intrinsic population of Milky Way BHs with cogsworth, self-consistently accounting for their binary evolution and trajectories through the Galactic potential. We report the rate, demographics, and kinematics of these BHs, and their sensitivity to 32 variations in binary evolution, supe…

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astro-ph.GAastro-ph.COastro-ph.HE2026年7月25日

Speeding up Gravitational Lens Mass Models with Machine Learning: Applications in X-ray Astronomy

Alex Ostridge, Rafael Martínez-Galarza, Júlia M. Sisk-Reynés, Daniel A. Schwartz, Anna Barnacka

Multi-wavelength observations of quadruply lensed quasars constitute a powerful probe of cosmology, dark matter substructure along the line of sight, and the structure of X-ray emitting regions in high-redshift quasars. These investigations are conditional on acquiring an accurate model for the surface mass density of matter lensing these quasars. We propose a simulation-based machine learning method to accelerate parameter inference in real quadruply lensed systems by several orders of magnitud…

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astro-ph.GAastro-ph.SR2026年7月25日

LBT-MODS spectroscopy of young stellar objects in the distant metal-poor star forming region Sh2-284: Stellar and accretion properties

Katia Biazzo, Juan Manuel Alcalá, Felice Cusano, Mario Guarcello, Diego Paris, Ester Marini, Roberta Carini, Teresa Giannini et al.

We present a spectroscopic survey of young stellar objects (YSOs) in Sh2-284, a distant (~4.5 kpc), low-metallicity (Z~1/3 Zsun) star-forming region (SFR) toward the Galactic anticenter. Candidate YSOs were selected using mid-infrared Spitzer/IRAC data with optical and near-infrared photometry. Follow-up spectroscopy was conducted with MODS at the Large Binocular Telescope. We characterize the stellar and accretion properties of the disk-bearing population in a metal-poor environment, probing st…

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astro-ph.GAastro-ph.HEastro-ph.SR2026年7月25日

Is S301 the Captured Companion of the Hypervelocity Star S5-HVS1?

Andrea Caputo, Giovanni Maria Tomaselli

Stellar binary disruptions through the Hills mechanism produce two fossils: a hypervelocity star (HVS), and a star tightly bound to the supermassive black hole. Among known galactic HVSs, only S5-HVS1 has unambiguous galactic-centre origin. Its measured mass and velocity determine a relation between the mass and semi-major axis of its captured companion. GRAVITY has now discovered S301, whose orbit and photometrically inferred mass satisfy this relation, making it the only compelling candidate f…

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astro-ph.IM2026年7月25日

Pollux: decisions affecting the optical architecture of a high-resolution spectrograph and polarimeter for the Habitable Worlds Observatory

Eduard Muslimov, Luca Fossati, Coralie Neiner, Jean-Claude Bouret, David Le Mignant, Kjetil Dohlen, Jean-Michel Reess, Adrien Girardot et al.

POLLUX is a candidate European instrumental contribution to the Habitable Worlds Observatory. It is a high-resolution spectrograph with polarimetric capabilities, covering from the far ultraviolet (FUV; 100nm) to the near infrared (NIR; 1.75mum). Such a broad spectral coverage is achieved by splitting the instrument into five channels, each comprising an echelle spectrograph: FUV, medium-UV (MUV), near-UV (NUV), optical (OPT), and NIR. A set of custom-made dichroics enables simultaneity across t…

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astro-ph.SRastro-ph.GA2026年7月25日

Payne4GAIN: NLTE Corrections for Red Giants in Milky Way Mapper using H-Band Neural Network Emulators

Pierre Thibodeaux, Alexander P. Ji, Nicholas Storm, Maria Bergemann, Rana Ezzeddine, Yuan-sen Ting, Andrew R. Casey, Emily Griffith et al.

The majority of spectroscopic surveys assume local thermodynamic equilibrium (LTE) during the modeling of stellar spectra. This assumption begins to break down for luminous stars, like the red giants targeted by SDSS-V's Milky Way Mapper Survey in its Galactic Genesis program. In this work, we present non-LTE (NLTE) abundances for 360,000 red giant stars in Milky Way Mapper DR19, from infrared APOGEE spectra. We generate NLTE spectra using precomputed departure coefficient grids for Na, Mg, Si,…

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astro-ph.IMastro-ph.EPastro-ph.SR2026年7月25日

Optical design of VIPER: a high-resolution multimode fiber-fed VIPA spectrograph for characterizing exoplanet atmospheric escape

Matthew C. H. Leung, David Charbonneau, Andrew Szentgyorgyi, Colby Jurgenson

We present the optical design of VIPER: a high-resolution, multimode fiber-fed, narrowband, cross-dispersed, seeing-limited spectrograph based on a Virtually Imaged Phased Array (VIPA), a spectral disperser that provides higher dispersion and a more compact form factor than conventional diffraction gratings. VIPER is specifically designed to probe exoplanet atmospheric escape through the helium 1083 nm triplet line, with a resolving power of 300,000 over a 10 nm wavelength range. VIPER is intend…

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