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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.GA

Euclid Quick Data Release (Q1). A systematic study of the intracluster light fraction at 0.2 < z < 1.5

Euclid Collaboration, H. Gully, N. A. Hatch, H. Gao, S. P. Bamford, J. B. Golden-Marx, A. Fernandez, T. Kolcu et al.

We present a homogeneous analysis of the intracluster light (ICL) in approximately 300 galaxy clusters spanning $0.2 10^{10}\,M_\odot$). The inferred ICL fraction also depends systematically on wavelength, while remaining largely insensitive to the adopted outer integration radius of 200-600 kpc. These results highlight the importance of homogeneous ICL analyses and constrain the evolution of diffuse stellar components in clusters.

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astro-ph.GA

Euclid Quick Data Release (Q1). Data processing for intracluster light measurements

Euclid Collaboration, S. P. Bamford, H. Gao, N. A. Hatch, T. Kolcu, A. Fernandez, G. Martin, Y. M. Bahé et al.

The Euclid survey provides images with extraordinary potential for studies of the low-surface-brightness Universe, including intracluster light (ICL). However, to realise this promise, the data must be carefully treated to minimise background variations while preserving the signal from diffuse structures. In this work, we describe the post-processing and measurement procedures used for studies of ICL with Euclid. We demonstrate that we are able to substantially reduce background variations witho…

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astro-ph.GA

Euclid Quick Data Release (Q1). The shape of cluster haloes revealed by intracluster light

Euclid Collaboration, T. Kolcu, N. A. Hatch, A. Fernandez, S. P. Bamford, H. Gao, J. B. Golden-Marx, G. Martin et al.

Intracluster light (ICL) offers a luminous route for measuring the shapes and orientations of cluster haloes. We used Euclid Quick Data Release (Q1) images to quantify ICL shapes for 205 clusters at $0.1 \leq z \leq 0.8$ selected from the eROSITA All-Sky Survey and the Dark Energy Survey. We measured the ICL properties across five bands ($I_\mathrm{E}$, $Y_\mathrm{E}$, $J_\mathrm{E}$, $H_\mathrm{E}$ and the coadded $YJH_\mathrm{E}$), and find that the shape parameters are consistent across the f…

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cs.LGastro-ph.IM

Probabilistic Machine Learning for Short-Term Atmospheric Seeing Forecasting

Mary-Joe Medlej, Rahul Srinivasan, Simon Prunet, Aziz Ziad, Christophe Giordano

Accurate short-term forecasting of atmospheric seeing is of significant interest for astronomical observations and free-space optical communication systems, where rapid variations in optical turbulence can affect system performance and operational planning. In this work, we benchmark machine learning models for predicting atmospheric seeing up to two hours in advance, with a particular focus on probabilistic forecasting and uncertainty quantification. We compare two probabilistic approaches, Gau…

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astro-ph.IMphysics.optics

Optimization of Petal-Shaped Occulters for Exo-Earth Observation

Simon Prunet, Céline Theys, Claude Aime

Petal-shaped occulters are giant, formation-flying optical devices designed for use in space astronomy. Their primary function is to block the intense starlight to enable the direct observation of exoplanets, a process challenged by the extreme contrast ratio (lower than 1e-10 for an exo-Earth). This study focuses on optimizing the shape of the occulter in order to significantly reduce Fresnel diffraction. For a circular occulter, the diffraction pattern shows the bright Arago spot. Nevertheless…

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astro-ph.EP

OGLE-2013-BLG-1125/MOA-2013-BLG-584: Discovery of a gas giant orbiting an M dwarf

E. Bachelet, M. Hundertmark, V. Bozza, J. -P. Beaulieu, A. Udalski

We report the discovery and characterization of a planetary system in the microlensing event OGLE-2013-BLG-1125/MOA-2013-BLG-584. We analyze photometric data from OGLE and MOA surveys, as well as LCO, $μ$FUN, and Mindstep follow-up telescopes to model the microlensing light curve. We also used data from the Keck II telescope collected in 2018 to obtain additional constraints on the lensing system. We found a Saturn-mass planet of mass $M_{\rm p}=105\pm13 \ M_\oplus$ orbiting a low-mass host star…

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astro-ph.COastro-ph.GA

HETDEX [OII] galaxies at $z \le 0.48$: Growth of structures from power spectrum multipoles

Jeongin Moon, Eiichiro Komatsu, Robin Ciardullo, Daniel J. Farrow, Karl Gebhardt, Caryl Gronwall, Gary J. Hill, Donghui Jeong et al.

We use the monopole and quadrupole power spectra of [\ion{O}{2}]-emitting galaxies in the HETDEX Public Data Release 1 to constrain the growth of cosmic structures at $z\le0.48$. We interpret the power spectra using a simulation-based model built from the Mucho-Uchuu-1G $N$-body simulation. The best-fit model reproduces the observed power spectra remarkably well up to $k_\mathrm{max}=0.7~h~\mathrm{Mpc}^{-1}$, and goodness-of-fit tests confirm that the HETDEX [\ion{O}{2}] clustering is consistent…

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astro-ph.SRastro-ph.HEastro-ph.IM

Confirming candidate self-lensing binary detections with radial velocity measurements

Adam McMaster, Madeline-Mai Ward, Hugh J. Dickinson, Matthew J. Middleton, D. J. Dixon, Adam Ingram, N. Castro Segura, Simon Vaughan et al.

Compact objects in approximately edge-on binary orbits with stars are able to produce a self-lensing effect, amplifying light from their companion once per orbit. To date, five white dwarf self-lensing systems are known, while none are known containing black holes or neutron stars. Discovery of such systems is a potential method of finding quiescent black holes and neutron stars, most of which will be pristine and unchanged from their formation. Photometric detections can suffer from degeneracie…

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astro-ph.HEastro-ph.COhep-ph

Domain models of turbulent magnetic fields and the spectral shape of ensemble averaged axion-photon conversion

Oleksandr Khasai, Lidiia Zadorozhna, Denys Malyshev, Oleg Ruchayskiy

Axion-like particles are light pseudoscalars that appear in many extensions of the Standard Model and are candidates for dark matter. Through their mixing with photons, they imprint energy dependent modulations on the spectra of astrophysical sources shining through magnetised media. When a distant source shines through the turbulent magnetic field of an intervening galaxy cluster, these modulations are stochastic. It has recently been shown that averaging over an ensemble of such sources instea…

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astro-ph.EPastro-ph.HEastro-ph.SR

Radio and high-energy variable emission from a multi-wavelength follow-up of the infant planet-hosting star V1298 Tau

M. Damasso, D. Viganò, R. Spinelli, S. Kaur, A. Petralia, Á. Sánchez-Monge, A. F. Lanza, A. Maggio et al.

V1298 Tau is a very young and magnetically active K1V star which hosts a benchmark multi-planetary system to study planet formation and evolutionary history at the earliest stages. Between 2025 and 2026, we conducted a campaign to monitor the variability of V1298 Tau in radio (band C), X-ray, and NUV bands, with the support of publicly available contemporary optical light curve, and to investigate multi-band correlations to link the emission with stellar activity. Radio observations were carried…

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astro-ph.HE

Searches for coincident Gravitational Waves and High-Energy Neutrinos from the KM3NeT and ANTARES telescopes during O3

ANTARES Collaboration, KM3NeT Collaboration, O. Adriani, A. Albert, A. R. Alhebsi, S. Alshalloudi, S. Alves, M. E. S. Alves et al.

Various models predict that gravitational-wave sources produce high-energy neutrinos. Among them are compact binary coalescences with at least one neutron star, but also core-collapse supernovae or accretion disk instabilities. Two different analyses are presented, combining data from the LIGO and Virgo gravitational-wave detectors with those from the ANTARES and ORCA neutrino telescopes observed during the third observing run of LIGO-Virgo. In the first analysis, selected high-energy neutrino c…

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astro-ph.IMastro-ph.SR

Data-driven characterisation of variable source light curves with multimodal representation learning

M. Madarász, G. Marton, M. Audard

Surveys such as the Zwicky Transient Facility (ZTF) and the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) produce light curves for hundreds of millions of variables. Their characterisation traditionally relies on supervised classifiers with hand-crafted features and curated labels, limiting them to predefined taxonomies and individual surveys. We present a general, survey-agnostic framework that characterises variable sources without labelled training data, producing low-dimen…

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astro-ph.GA

FEAST: Spatially Resolved Star Formation History of the NGC 4485/NGC 4490 System and its Tidal Bridge from JWST/NIRCam Color Magnitude Diagrams

Giacomo Bortolini, Matteo Correnti, Angela Adamo, Michele Cignoni, Monica Tosi, Göran Östlin, Arjan Bik, Daniela Calzetti et al.

We present the spatially resolved star formation history (SFH) of the interacting, low-mass, gas-rich galaxy pair NGC 4485/NGC 4490, based on deep JWST/NIRCam imaging obtained as part of the FEAST program. Using resolved stars' near-infrared color-magnitude diagrams (CMDs) and the SFERA 2.0 CMD fitting code, we reconstruct the SFH of the system, including the tidal bridge connecting the two galaxies. We find that recent star formation is widespread across the system, extending beyond the main bo…

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gr-qcastro-ph.IM

Orientation-dependent sensitivity of the all-sky all-frequency gravitational-wave radiometer search to continuous-wave sources

Stavros Venikoudis, Giacomo Bruno

The all-sky all-frequency (ASAF) gravitational-wave radiometer search cross-correlates the data of two detectors with equal weight on the $+$ and $\times$ tensor polarizations. This is optimal for an unpolarized stochastic background, but not for continuous-wave (CW) sources, whose polarization depends on the inclination angle $ι$ and the polarization angle $ψ$. Unless the source is seen face-on, the search measures less power than a face-on source with the same intrinsic amplitude, and underest…

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astro-ph.EP

Surface regolith model of near-Earth asteroid (3200) Phaethon

Mikko Vuori, Antti Penttilä, Karri Muinonen, Hanna Pentikäinen, Ari Leppälä, Zuri Gray, Eric MacLennan, Mikael Granvik et al.

The near-Earth asteroid (3200) Phaethon displays activity as it comes close to the Sun and is presumed to be the progenitor of the Geminids meteor shower. Both CM- and CY-meteorites have been suggested as possible meteorite analogues for Phaethon. Previous spectral and polarization measurements of Phaethon indicate possible surface heterogeneity in the regolith properties. By combining mineral components and their size fractions, we present a regolith model for Phaethon that reproduces the spect…

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astro-ph.HEastro-ph.GAgr-qc

Lasting mEMRIs: Signatures of Multiple Black Hole Extreme Mass Ratio Inspirals from AGN discs

Jordan W. N. Moncrieff, Evgeni Grishin, Fiona H. Panther, Alessandro A. Trani

Encounters of stellar-mass black holes (sBH) in active galactic nuclei discs naturally form mean-motion resonances of sBH pairs. These mean-motion resonances can be broken close to the central supermassive black hole when gravitational-wave emission dominates over gas torques. We derive a simple condition that depends only on the sBH mass ratio and the resonance index for which a pair of sBH in a mean-motion resonance will remain intact and can be detectable as a multiple Extreme-Mass-Ratio-Insp…

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astro-ph.GAastro-ph.SR

Ballistic mixing: stellar mergers drive internal mixing in extremely massive stars, with implications for proto-globular cluster pollution

J. Roman-Garza, C. Charbonnel, A. Rantala, T. Fragos, M. Gieles, L. Ramírez-Galeano

Extremely massive stars, with masses of $10^3$-$10^4$ M$_\odot$, have been proposed as potential sources of the chemical enrichment associated with multiple populations in globular clusters. Early on the main sequence, these stars reach central temperatures of 65 to 75 MK, enabling nucleosynthesis through the CNO, NeNa, and MgAl cycles, producing abundance patterns similar to those observed in the so-called cluster's second population. Stellar mergers are among the leading formation channels for…

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astro-ph.SRastro-ph.GAastro-ph.IM

simesh: A Python Framework for Quantitative Analysis of Native AMR Data from MPI-AMRVAC

Hao Wu, Jinhan Guo, Rony Keppens, Yang Guo

Adaptive mesh refinement (AMR) is widely used in large-scale astrophysical simulations, but the resulting multilevel data are challenging to analyze quantitatively. We present simesh, an independent Python framework for quantitative analysis of cell-centered fields on block-structured AMR meshes. The current implementation targets three-dimensional Cartesian datasets from MPI-AMRVAC and compatible AGILE snapshots, preserving the native AMR hierarchy and connecting complementary scientific diagno…

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astro-ph.SRastro-ph.GAastro-ph.IM

simesh: A Python Framework for Quantitative Analysis of Native AMR Data from MPI-AMRVAC

Hao Wu, Jinhan Guo, Rony Keppens, Yang Guo

Adaptive mesh refinement (AMR) is widely used in large-scale astrophysical simulations, but the resulting multilevel data are challenging to analyze quantitatively. We present simesh, an independent Python framework for quantitative analysis of cell-centered fields on block-structured AMR meshes. The current implementation targets three-dimensional Cartesian datasets from MPI-AMRVAC and compatible AGILE snapshots, preserving the native AMR hierarchy and connecting complementary scientific diagno…

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astro-ph.SR

Enhanced Mass Transfer from Extended Shock-Supported Stellar Chromospheres

Soumyadeep Bhattacharjee, Jim Fuller, Kareem El-Badry

Mass transfer (MT) in binary systems is a crucial and complex process. Even before the donor's photosphere fills its Roche lobe, matter from its outer atmosphere can reach the inner Lagrange point, thus initiating interaction in the so-called optically thin phase. Most existing models account for a very tenuous atmosphere supported by thermal gas pressure, thus predicting very little MT until the donor fills its Roche lobe. However, recent hydrodynamic simulations of giant stars suggest that sho…

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astro-ph.GAastro-ph.IM

B-fields In STar-forming Region Observations (BISTRO): Dual-Wavelength Constraints on Size-Dependent Grain Alignment in Star-Forming Regions

Ray S. Furuya, David Berry, Pierre Bastien, Tetsuo Hasegawa, Masafumi Matsumura, Thiem Hoang, Lapo Fanciullo, Kazunari Iwasaki et al.

We compared 450 and 850 $μ$m POL-2 observations from the James Clerk Maxwell Telescope at $12.6''$ resolution. The median absolute difference in polarization angle between bands is $6.7^\circ$ across 21 regions. For total intensity $I\proptoν^α$ and polarized intensity $PI\proptoν^γ$, 24-27 of 35 regions have $γ<α$, allowing for $3σ$ limits on weak polarized intensities. The median $γ-α$ is $-0.51$, ranging from $-0.57$ to $-0.45$ under these limits. The ratio of polarization fractions is $P_{45…

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astro-ph.GAastro-ph.IM

B-fields In STar-forming Region Observations (BISTRO): Technical Foundations for Quantitative 450/850 $μ$m JCMT SCUBA-2/POL-2 Polarimetry

Ray S. Furuya, David Berry, Pierre Bastien, Tetsuo Hasegawa, Masafumi Matsumura, Koji Kawabata, Kazunari Iwasaki, Per Friberg et al.

We present five technical validations of SCUBA-2/POL-2 polarimetry on the James Clerk Maxwell Telescope at 450 and 850 $μ$m, using 174 archival fields in 69 molecular cloud regions and subsets appropriate to each test. Extended-source calibration avoids a deterministic shift of $Δβ=-1.05$ in the dust emissivity index $β$ that would result from calibrating extended emission using peak brightness. We modeled Stokes $I$ noise with additive and signal-dependent components. The measured median ratio…

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astro-ph.HEgr-qc

General Relativistic Simulations of the Nonlinear Evolution of r-modes in Rapidly Rotating Neutron Stars

Justin K. Yu, Andrew Melatos

The r-modes in rotating neutron stars are a promising source of continuous gravitational waves, and may grow or be excited to amplitudes $α\lesssim1$. We perform general relativistic simulations of nonlinear $l=|m|=2$ r-modes in a rapidly rotating neutron star with spin frequency $f_{spin}\approx792$ Hz, relaxing the Cowling and small-$α$ approximations. The star is idealised as an unmagnetised, one-component, perfect fluid with a polytropic equation of state. The r-mode frequency is measured to…

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gr-qcastro-ph.HEastro-ph.IM

How general relativity stacks up: Testing gravity by coherently combining gravitational-wave observations

Lachlan Passenger, Nir Guttman, Paul D. Lasky, Eric Thrane

A core mission of gravitational-wave astronomy is to test general relativity (GR) in the high-curvature, high-velocity regime. The field has already seen significant progress in this space, though a remaining challenge is how to combine data from a population of binary mergers. This can both boost the significance of potential GR violations, and develop a phenomenological picture of how deviations manifest in different mergers. We propose a framework to coherently combine gravitational-wave meas…

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nucl-thastro-ph.SR

Hybrid Stars with a Crossover Equation of State

G. A. Tsalis, Ch. C. Moustakidis

The possible occurrence of a phase transition in superdense nuclear matter remains an open problem in nuclear physics. In particular, the transition from purely hadronic matter to the hypothesized deconfined quark matter is a subject of considerable interest. Beyond its fundamental significance, this transition has important implications for the physics of compact objects, including neutron stars, quark stars, and hybrid stars. The conventional approaches to this problem involve the Maxwell and…

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astro-ph.HE

Double-Shock Radiation in Supernova Wind Breakout and EP260321a

Zhuo Li, Rui-Ze Shi, Qiang Wang

We study the supernova (SN) shock breakout (SBO) from an optically thick stellar wind. The SN ejecta-wind interaction forms a forward shock (FS) plus reverse shock (RS) structure. The RS's internal energy and shock velocity are both a fraction $μ\lesssim1/6$ of the FS's. The lower RS velocity makes it easier to build up local thermal equilibrium (LTE) and generate blackbody (BB) emission. In the same time a $μ^{-1}\gtrsim6$ times larger non-BB emission may be produced by the likely non-LTE FS. W…

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astro-ph.GA

Unveiling Accretion-Disk Reverberation Beneath BLR Contamination with TILDE

Sungho Jung, Jong-Hak Woo

We present a Bayesian framework, Two-stage Inference for Light curve DEcomposition (TILDE), for mapping the accretion disk and the broad line region (BLR) from active galactic nuclei (AGN) multi-band light curves. By inferring delayed BLR contamination from the underlying disk variability, TILDE provides the delay measurements of the disk as well as the BLR. We validate TILDE using synthetic data, finding that TILDE recovers the known time delays of the disk and BLR. By applying TILDE to the Seo…

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astro-ph.GAastro-ph.HE

NGC 3227 Blinks: An Extreme Changing-Look Event in a Seyfert Galaxy

Kaiwen Zhang, Michael S. Brotherton, Pu Du, Dong-Wei Bao, Bi-Xuan Zhao, Feng-na Fang, Yan-Rong Li, Chen Hu et al.

We report a rapid optical changing-look event in the Seyfert galaxy NGC 3227: the optical continuum faded by more than 70% and broad H-beta emission nearly disappeared within weeks, before recovering within two months. Damped random walk simulations calibrated to the source's normal variability show that such a decline is unlikely for stochastic accretion fluctuations (p = 0.002). Simultaneous Swift monitoring reveals X-ray spectral hardening, pointing to enhanced line-of-sight absorption. Durin…

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astro-ph.HE

Investigating a TeV-Halo Candidate around PSR J1928+1746 with HAWC

The HAWC Collaboration, R. Alfaro, C. Alvarez, A. Andrés, E. Anita-Rangel, M. Araya, J. C. Arteaga-Velázquez, D. Avila Rojas et al.

We present an updated High-Altitude Water Cherenkov (HAWC) analysis of the crowded Galactic-plane area near PSR J1928+1746, which was previously linked to the extended source 3HWC J1928+178. With 2904 days of HAWC data, improved event reconstruction, and a multicomponent likelihood model that includes six TeV source components and Galactic diffuse emission, we describe the region using six components and find a distinct, moderately extended source close to PSR J1928+1746. This source, HAWC J1928…

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astro-ph.GA

The MAGE Project: Size Evolution and Disk Formation in Massive Galaxies at Cosmic Dawn

Zhiyuan Yao, Avishai Dekel, Romain Teyssier, Rachel Somerville, Nir Mandelker, Zachary Andalman, Ulrich Steinwandel, Zhaozhou Li et al.

We investigate size evolution and disk formation with a new suite of eleven cosmological zoom-in simulations, Massive Assembly of Galaxies in the Early universe (MAGE), run with RAMSES at $\sim10\,\mathrm{pc}$ resolution until $z\simeq9$. The target galaxies span stellar masses of $M_\star\simeq2\times10^8$-$3\times10^{10}\,M_\odot$ at $z=9$. The stellar half-mass radius grows steeply with stellar mass at low masses, turns over near $M_\star\simeq5\times10^9\,M_\odot$, and evolves weakly with re…

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