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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.EP

Migration and Evolution of giant ExoPlanets (MEEP). III. Twenty-Nine Giant Planets from the TESS Mission

Jack Schulte, Joseph E. Rodriguez, David W. Latham, Allyson Bieryla, Karen A. Collins, Samuel N. Quinn, Xian-Yu Wang, Rafael Brahm et al.

We present the discovery and characterization of 29 hot and warm Jupiter systems transiting bright ($G < 12.8$) FGK stars using TESS data and ground-based photometry and spectroscopy. Through the use of high angular resolution imaging, we discovered three bound stellar companions, named TOI-3988 B, TOI-6171 B, and TOI-7266 B. The planets that we confirmed span an orbital period range of $1.28 - 16.9$ days, a mass range of $0.35 - 8.7$ $\mathrm{M}_{\mathrm{J}}$, and an orbital eccentricity range…

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astro-ph.EP

Space Journey Beyond Earth: Exploring the properties of exoplanets and multi-planetary systems

Alexandra Muresan

In contrast to the observed exoplanet diversity, planets within many multi-planetary systems exhibit intra-system similarities in their radii, masses, and orbital spacings. This thesis investigates the planetary properties and system architectures, focusing on the intra-system similarities, the inferred planetary interior compositions, and the differences between single- and multi-planetary systems. Paper A shows that planets within the same system tend to have similar orbital spacings even when…

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astro-ph.GA

Cosmic Collisions I: Optical Morphologies for MIRI-selected galaxies from the PRIMER survey

Gregory Troiani, Allison Kirkpatrick, Leyna Bajaj, Joseph Havens, Jackson Stephens, Anton M. Koekemoer, James S. Dunlop, Adriano Fontana et al.

We present the first results of visual morphology classifications from the Cosmic Collisions project, comprising 14,657 galaxies from the JWST Public Release IMaging for Extragalactic Research (PRIMER) survey. The sample consists of galaxies detected with MIRI F770W and spans the epoch of peak cosmic star formation (1 2. This inverts findings from optical selection, which shows galaxies becoming more bulge-dominated and elliptical over cosmic time. In addition, we identify a population of galaxi…

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astro-ph.IMastro-ph.COgr-qcphysics.data-an

Fisher and DALI posterior approximations for testing gravity with gravitational waves

Felipe A. da Silva Barbosa, Davi C. Rodrigues, Josiel Mendonça Soares de Souza, Miguel Quartin

We investigate the accuracy and computational efficiency of posterior approximations for gravitational-wave (GW) parameter estimation based on Fisher Matrix and its higher-order extension, the Derivative Approximation for LIkelihoods (DALI), in the context of tests of General Relativity using parameterized deviations in the inspiral waveforms (the TIGER formalism). We adopt the \texttt{IMRPhenomD} waveform and compare the exact posterior sampling to the following approximations in increasing ord…

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astro-ph.IMphysics.data-anstat.ML

PTED: A multi-dimensional two-sample test for scientific inference and generative machine learning

Connor Stone

Two-sample tests are widely applicable in inference and generative modelling, yet users frequently fall back on heuristics and visual inspection due to lack of an accessible test that operates in multiple dimensions. I present Permutation Test using the Energy Distance (PTED), a Python implementation of a powerful two-sample test described in Székely and Rizzo [2004]. The test statistic is the energy distance, a metric on probability distributions that admits a natural sample estimator built fro…

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astro-ph.HEastro-ph.GA

NEXUS: Discovery of a Luminous Young Transient at $z=5$

Ming-Yang Zhuang, Yue Shen, Lei Hu, Justin D. R. Pierel, Zhiwei Pan, Zachary Stone, Adam J. Burgasser, Xiaohui Fan et al.

We report the discovery of AT 2026abck, a young transient in a star-forming galaxy at $z=5.017\pm0.001$, identified from Year-2 observations of the NEXUS JWST treasury program. AT 2026abck was detected on 2026 Aug 7 in NIRCam F200W imaging, with contemporaneous detection from parallel NIRCam F150W+F277W imaging. It brightened by $>1.4$ mag in F200W over $\lesssim 12$ rest-frame days, as inferred from the last non-detection. AT 2026abck has nearly identical magnitudes of $\sim27.4$ mag in F150W,…

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astro-ph.GA

A New Hope for AGN SED Fitting: X-Ray Spectral Analysis of 12MGS AGN with the C2PO-Torus Model

Carys J. E. Gilbert, Lucia Marchetti, Luigi Barchiesi, Mattia Vaccari, Cristian Vignali, Stefano Marchesi, Francesca Pozzi, Francesco Salvestrini et al.

In this paper, we present the results of comprehensive, broadband X-ray spectral analysis of a subsample of 43 mid-Infrared (IR) selected star-forming active galactic nuclei (AGN). We analysed archival NuSTAR, Chandra, and XMM-Newton data, and present the first pointed X-ray observation of IRASF03450+0055. We introduce a new physically-based X-ray spectral model, C2PO-Torus, based on a two-phase clumpy torus geometry. It is designed to provide constraints on physical parameters of the torus that…

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astro-ph.HEastro-ph.IM

VLBI Astrometric Procedure and Performance with CHIME/FRB Outriggers

Shion Andrew, Mattias Lazda, Calvin Leung, Kiyoshi W. Masui, Danté M. Hewitt, Jacob Willis, Alyssa Atkinson, Kevin Bandura et al.

Precise localizations of fast radio bursts (FRBs) to specific environments within their host galaxies with very-long-baseline interferometry (VLBI) have provided valuable insights into the nature of their progenitors. To date, such localizations have relied primarily on traditional VLBI facilities, whose observational capabilities limit them to targeted follow-up on a small subset of repeating FRBs that are observable at frequencies above $\sim$1 GHz. CHIME/FRB Outriggers is a low-frequency (400…

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astro-ph.HEastro-ph.SRhep-ph

HESS J1507-622: A Plausible Young Galactic Kilonova Remnant

Prantik Sarmah, Xilu Wang, Myles Carley, Shu-Xu Yi, Ming-Yu Ge, Rebecca Surman

HESS J1507$-$622 is an unusual TeV gamma-ray source in the H.E.S.S. Galactic Plane Survey, distinguished by its off-plane location ($b \simeq -3.5^{\circ}$) and compact angular extent ($\sim 0.3^{\circ}$). Its location and morphology challenge conventional pulsar wind nebula and supernova remnant interpretations, and the absence of a detected shell or associated pulsar leaves its origin unresolved. Here, we propose that HESS J1507$-$622 is a young Galactic kilonova remnant with gamma-ray emissio…

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astro-ph.HEastro-ph.GA

Cosmic-neighbor-associated distances to VHE and candidate VHE BL Lacs via SDSS photometric redshifts

Karri I. I. Koljonen, Elina Lindfors

BL Lac objects have distances that are difficult to estimate because their optical spectra rarely show identifiable emission or absorption lines. We present a method to constrain BL Lac distances by associating them with their cosmic neighborhoods (local overdensities in the cosmic web) identified in optical fields. Distances to galaxies in these neighborhoods are estimated using the Sloan Digital Sky Survey (SDSS) photometric redshifts. Using cosmic-neighborhood associations previously establis…

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astro-ph.GA

Learning Gaia: A Generative Model Trained on the Gaia Data Release 3 Source Catalog

John Soltis

I train a conditional flow matching model on the positions, photometry, and astrometry of $\sim$ 579 million sources from the Gaia Data Release 3 Source Catalog. Using a probabilistic masking scheme during training, I develop a model capable of generating mock Gaia catalog sources with and without partial measurements of real Gaia sources. The model can produce coarse-grained mock Gaia Source Catalogs that reproduce the Milky Way disk and Magellanic Clouds, and can impute photometric and kinemat…

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astro-ph.HEastro-ph.GA

Revealing the accretion disc structure in Changing State AGN: NGC1566

Huimei Wang, Chris Done, Riccardo Middei, Xue-Bing Wu

NGC1566 is a low mass ($\sim 6\times 10^6M_\odot$) Active Galactic Nuclei (AGN) with unusual large amplitude variabilty in its accretion flow. In the optical it cycles between recurring short bright episodes with strong blue/UV continuum and clear broad line emission, and a much weaker persistent level without strong broad lines, making it a repeating changing-state (CS) AGN. We re-analyse the intensive optical/UV and X-ray monitoring during the 2018 bright flare, showing for the first time the…

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astro-ph.IMastro-ph.GAastro-ph.HE

An X-ray Extremely wide-field Spectroscopic Surveyor (XESS, or "chess")

W. P. Maksym, M. Ulmer, S. Friedrich, F. Tombesi, R. Arcodia, S. P. Singam, S. Bongiorno, N. Thomas et al.

We propose an X-ray observatory, the X-ray Extremely wide-field Spectroscopic Surveyor (XESS, pronounced "Chess") to bring high energy resolution X-ray spectroscopy into the era of synoptic surveys and of time domain and multi-messenger astrophysics (TDAMM). Such an observatory is optimally suited to addressing key elements of the 2020 Decadal Survey on Astronomy and Astrophysics.

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astro-ph.SR

Surveying for Close Binaries among Lithium-rich Giants

Jesús Torres, Sebastián Vilaza-Dallago, Julio Chanamé, Rafael Brahm

One of the possible scenarios usually considered to explain the existence of low-mass red giants with anomalously high lithium (Li) abundances requires the interaction with a close binary companion. If dominant, this enrichment channel predicts a significantly enhanced binary fraction among Li-rich giants relative to Li-normal ones. We aim to constrain the binary interaction hypothesis by using multi-epoch radial velocities (RVs) to measure the close binary fraction of a statistically robust sam…

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astro-ph.EP

An Infant Sub-Saturn in Scorpius-Centaurus

Gurmeher Kathuria, Luke G. Bouma, Andrew W. Boyle, Roberto Tejada Arevalo, Andrew W. Mann, Nidia Morrell, Karen A. Collins, R. Paul Butler et al.

We report the discovery and validation of TIC 88297141 Ab, a transiting planet orbiting a pre-main-sequence M dwarf (0.31 solar masses, 0.74 solar radii) in the Scorpius-Centaurus OB association. Group membership implies an age of $15.6 \pm 1.6$ Myr, supported by lithium and isochrone age-dating. We detected the TESS transits using a custom pipeline designed for variable stars and used ground-based photometry (LCO/Swope and LCOGT/Sinistro) to confirm the on-target nature of the signal. Our globa…

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astro-ph.IMcs.LG

Gestalt: a meta-foundation model for astronomy

Michael J. Smith, Shashwat Sourav

The Platonic Representation Hypothesis predicts that sufficiently scaled foundation models converge on a shared representation of the world. As each non-converged model gives a noisy view of a common structure when passed the same input, we ask whether we can combine models into a representation that outperforms its individual components. We test this on galaxies: we embed images via a basket of 22 frozen foundation models from eight families, whiten each view, and take a randomised SVD of the e…

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astro-ph.COastro-ph.GA

Testing Offsets Between Cluster-Scale Halos and BCGs in Strong Lensing Models Using the Jackknife Method

Sangjun Cha, Marceau Limousin, M. James Jee

Offsets between cluster-scale dark matter halos and brightest cluster galaxies (BCGs) inferred from strong lensing (SL) models have been used to investigate cluster dynamics and dark matter physics. However, it is necessary to test whether these offsets are required by SL data themselves. We investigate whether allowing these offsets improves predictive accuracy and examine the effects on magnification, time-delay predictions, and critical curve positions. We evaluate lens models of Abell 370, R…

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hep-phastro-ph.COastro-ph.HE

How collective modes terminate in the dispersion relation of neutrino plasmas

Damiano F. G. Fiorillo

Neutrino plasmas support flavor waves, collective oscillations of flavor, that neutrinos can resonantly emit or absorb when they fulfill the Cherenkov condition. For massless neutrinos, this condition leads to singular features in the dispersion relation: Landau-damped modes, for example, disappear abruptly as their phase velocity approaches the speed of light. We investigate how these singularities change when nonzero neutrino masses introduce a spread in velocities. We classify singular behavi…

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astro-ph.COastro-ph.GA

Testing Offsets Between Cluster-Scale Halos and BCGs in Strong Lensing Models Using the Jackknife Method

Sangjun Cha, Marceau Limousin, M. James Jee

Offsets between cluster-scale dark matter halos and brightest cluster galaxies (BCGs) inferred from strong lensing (SL) models have been used to investigate cluster dynamics and dark matter physics. However, it is necessary to test whether these offsets are required by SL data themselves. We investigate whether allowing these offsets improves predictive accuracy and examine the effects on magnification, time-delay predictions, and critical curve positions. We evaluate lens models of Abell 370, R…

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astro-ph.HE

Nearby Supernova Science in the Era of High Cadence, Deep Time Domain Surveys

David J. Sand, Bhagya Subrayan, Conor L. Ransome, Griffin Hosseinzadeh, K. Azalee Bostroem, Jennifer E. Andrews, Jeniveve Pearson, Yize Dong et al.

We discuss science opportunities for nearby supernovae (SNe) in the era of the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST), emphasizing the youngest phases of SN evolution and the value of contemporaneous high-cadence shadowing surveys. LSST's Wide Fast Deep survey will discover enormous numbers of SNe, but its $\sim 3$ day cadence will miss signatures that evolve on timescales of hours to days, requiring cadence augmentation by other programs. We present simple depth and…

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astro-ph.HEastro-ph.GA

Not So Heavy Metal I: Low Metallicity Enhances the Rate of high-redshift Superluminous Supernovae

Ben Margalit, Allison L. Strom, Cristina Andrade, Michael W. Coughlin, Adam A. Miller, Steve Schulze, Ved G. Shah

Type-I superluminous supernovae (SLSNe) are extremely luminous stellar explosions originating from the core collapse of massive stars. Unlike normal core-collapse supernovae, however, SLSNe occur almost exclusively in metal-poor environments. As a result, their volumetric rate should not simply trace the cosmic star-formation history, but instead evolve with the metallicity distribution of galaxies across cosmic time. In this work, we introduce a new theoretical framework for modeling the volume…

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astro-ph.GA

LYRA: The formation and growth of nuclear star clusters in dwarf galaxies

Joaquin Sureda, Azadeh Fattahi, Sownak Bose, Mariya Lyubenova, Jessica E. Doppel, Thales Gutcke, Katja Fahrion, Rüdiger Pakmor et al.

Nuclear star clusters (NSCs) are dense massive star clusters ubiquitous in galactic centres across various mass regimes, present in up to $\sim30$ per cent of dwarf galaxies with $M_\star<10^{7}\, \mathrm{M}_\odot$. Although their main growth pathways are well studied, there is still ongoing debate regarding their formation. We use the LYRA cosmological hydrodynamical simulations to study the formation and growth of NSCs in a sample of six dwarf galaxies, where we identify NSCs with masses $M_\m…

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astro-ph.EPphysics.ao-phphysics.flu-dyn

Atmospheric dynamics and variability of periodically irradiated tidally locked planets

Deepayan Banik, Vasilii Pustovoit, Thaddeus D. Komacek, Marta L. Bryan

Time-variable stellar heating may create new climate states, such as permanently hot or cold hemispheres, on asynchronous planets. Planets on eccentric orbits, circumbinary planets and planets on polar orbits around gravity-darkened stars all receive variable irradiation, yet variably irradiated planets (VIPs) have not been studied from a fundamental dynamical perspective. We present the first generalized study of the atmospheric response of variably irradiated tidally locked planets, using a 1.…

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gr-qcastro-ph.HEastro-ph.IM

Fast and Flow-rious: Gravitational Wave Background Bayesian Model Comparison using Normalizing Flows and Nested Sampling

David C. Wright, Aaron D. Johnson, Jeffrey S. Hazboun, William G. Lamb

In 2023, pulsar timing array (PTA) collaborations around the world announced evidence for a nanohertz gravitational-wave background (GWB). Beyond increasing the detection significance, the next major goal is to characterize the GWB and identify its source(s). The typical model-comparison metric used in PTA analyses is the Bayes factor (BF). However, BF computation methods used in the PTA literature, such as product-space sampling and thermodynamic integration, are computationally expensive or in…

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astro-ph.HE

Very High-Energy GRB Afterglow Fits with Neural-Network Emulation and Bayesian inference

Edilberto Aguilar-Ruiz, Jessica Saldívar Talavera, Ramandeep Gill, Sundar Srinivasan

The very high-energy ($E > 100$ GeV) afterglow emission in gamma-ray bursts (GRBs) can be explained by synchrotron self-Compton (SSC). Modeling this emission accurately requires fully numerical codes that solve the time-dependent coupled particle--photon kinetic equations while accounting for Klein--Nishina suppression. However, their substantial computational cost makes them impractical for traditional parameter inference techniques such as Markov Chain Monte Carlo (MCMC) sampling. In this work…

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astro-ph.GA

Discovery of the Lyman-$α$ Forest in a Star-Forming Galaxy at $z \approx 7.57$: Implications for the Timing and Topology of Cosmic Reionization

Jakob M. Helton, Joris Witstok, Marta Laska, Kevin N. Hainline, Nikko J. Cleri, Francesco D'Eugenio, Ignas Juodžbalis, Nimisha Kumari et al.

The escape of ionizing photons from galaxies during the Epoch of Reionization is often inferred indirectly because the intervening neutral hydrogen in the intergalactic medium (IGM) is expected to absorb all flux blueward of Lyman-$α$ at these redshifts. However, in this work, we report the significant detection ($\approx7σ$) of flux blueward of Ly$α$ in a massive ($M_{\ast}\approx10^{9.1}\ M_{\odot}$) star-forming galaxy at $z\approx7.57$, JADES-GS-z7-LAF, using JWST/NIRSpec PRISM spectroscopy.…

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nucl-thastro-ph.HE

Bayesian Constraints on Bosonic Dark Matter in Neutron Stars within a Covariant Density-Functional Equation-of-State Ensemble

Davood Rafiei Karkevandi, Alexander Ayriyan, Armen Sedrakian

We investigate neutron stars admixed with repulsively self-interacting bosonic dark matter (DM) using current multi-messenger observations. The dark component is modeled as a complex scalar field coupled to baryonic matter only through gravity, allowing dark-core and dark-halo configurations. To quantify baryonic equation-of-state (EOS) uncertainties, we combine a three-dimensional scan over $(m_χ,λ,F_χ)$ with 27 DDME2-based covariant density-functional EOSs spanning $L_{\rm sym}=30,50,70$ MeV a…

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astro-ph.GAastro-ph.IM

Detecting HI Self-Absorption using Neural Networks

Eric G. M. Muller, Naomi M. McClure-Griffiths, Hiep Nguyen, Matthew J. Alger, Frances Buckland-Willis, J. R. Dawson, Min-Young Lee, Antoine Marchal et al.

Cold atomic hydrogen plays a crucial role in the life cycle of interstellar gas. It serves as the intermediary phase in the condensation and cooling processes that bridge the warm diffuse gas in and around galaxies, and the cold molecular gas that drives star formation. HI self-absorption in the 21-cm emission line is the most direct observational tracer of cold HI gas that does not require a continuum background source, yet its systematic extraction remains a long-standing challenge. Existing m…

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astro-ph.HE

Science Using Single-Pulse Exploration with Combined Telescopes: II. Pulse profile evolution and single-pulse modulation

F. Jankowski, J. -M. Griessmeier, T. Roy, M. Surnis, G. Theureau, L. Bondonneau, P. Noe, J. Petri et al.

Aims. We aim to illuminate how the pulsars' integrated pulse profiles and single-pulse modulation evolve with radio frequency, while separating intrinsic and propagation effects. Methods. We present integrated pulse profiles and phase-resolved modulation indices for 12 radio pulsars at up to five frequency bands. Our wideband dataset was systematically acquired with the Nancay Radio Observatory telescopes and the uGMRT, covering the frequency range 10 MHz to 2.8 GHz, including NenuFAR, LOFAR FR6…

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astro-ph.EP

Radiation Hydrodynamics of Self-gravitating Protoplanetary Disks II. Accretion, Migration, Spin, and Internal Structure of GI Fragments

Yang Ni, Hongping Deng, Xue-Ning Bai

In the first paper of this series, we showed that gravitational instability (GI) in protoplanetary disks can produce fragments of planetary rather than brown-dwarf mass, leaving the subsequent evolution and ultimate fates of such fragments an open question. Here, we follow every bound object in a global three-dimensional radiation hydrodynamic simulation of a fragmenting $0.196\,M_\odot$ disk around a $1\,M_\odot$ star: seven surviving fragments, one disrupted clump, and one merged clump, follow…

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