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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

A radio counterpart of the local little-red-dot J092359+415736

Tao An, Ruqiu Lin, Ailing Wang

Little red dots (LRDs) are compact red sources at z>~4. Broad lines suggest accreting black holes, yet radio and X-ray measurements are usually weak. Local LRDs allow multi-frequency, multi-epoch radio studies that are inaccessible at high redshift. We search archival radio images for a counterpart to the local LRD J092359+415736 at z~0.323, quantify its long-term radio variability, and identify the plausible origin of the radio emission. Flux densities at the optical position are measured in FI…

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astro-ph.GA

Sulphur-bearing molecule survey towards prestellar and starless cores in the Perseus molecular cloud

J. Ferrer Asensio, S. Scibelli, A. Pokorny-Yadav, L. Steffes, B. Kulterer, Y. Shirley, A. Megías, I. Jiménez-Serra et al.

Sulphur is drastically depleted from the gas phase in dense starless and prestellar cores, creating the long-standing "missing sulphur problem". Observations of sulphur-bearing molecules are crucial to understanding sulphur chemistry, core-environment relationships, and the physical evolution of star-forming regions. We present a survey of four sulphur-bearing molecules, HCS+, OCS, H2CS, and SO, towards 15 starless and prestellar cores in the Perseus molecular cloud using the Yebes 40m telescope…

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astro-ph.SR

What Does 2D Coronal Seismology Measure?

Zihao Yang, Yuhong Fan, Giuliana de Toma, Sarah Gibson, Matthias Rempel

Two-dimensional (2D) coronal seismology based on coronagraphic imaging spectroscopy has emerged as a promising method for mapping the coronal magnetic field, but the physical meaning of its inferred quantities under optically thin line-of-sight (LOS) integration remains uncertain. We investigate this problem by synthesizing coronagraphic observables from a global wave-driven magnetohydrodynamic model with a long LOS extent and a structured corona, and by applying the same analysis procedures use…

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nucl-thastro-ph.HEhep-phhep-th

Internal Nucleon Properties and the Equation of State of Ultra-Dense Matter

Bikram Keshari Pradhan, Jérôme Margueron, Guy Chanfray, Hubert Hansen

The question of the link between the nucleon properties and the equation of state of ultra-dense matter, both being composed of quarks and gluons, is investigated by adopting a soliton model to describe internal nucleon properties and a direct mapping between nucleon and quark matter to obtain the equation of state of ultra-dense matter. We compare $π+ω$ and $π+ω+ρ$ soliton models and analyze the presence of a pressure singularity at the nucleon center due to the $ρ$ field. This singularity impa…

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astro-ph.SRastro-ph.GA

Henrietta Leavitt's classical Cepheid relation

Daniel Majaess

The Leavitt & Pickering (1912) mean period-magnitude relation for SMC Cepheids exhibits correlated residuals relative to modern Gaia $B_G$ and Johnson $V$ photometry ($r_{δV/δL12}\approx0.76$). Therefore dispersion inherent to Leavitt's photographic photometry relation is not solely random scatter ($σ_{L12,B_G,V}=0.22\pm0.03,0.25\pm0.04,0.20\pm0^{m}.03$), and is potentially consistent with the partial encoding of combined effects from the elongated SMC, classical Cepheid instability strip, diffe…

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astro-ph.IM

Simulation and Deep Learning Inversion for Full-sky Energetic Neutral Atom Imaging at the Heliospheric Boundary

Weining Wang, Rong Lin, Jiansen He, Hong Zou, Yongfu Wang, Jiali Chen, Yuguang Ye, Weihong Shi et al.

The distribution of energetic neutral atom (ENA) differential flux density at the heliospheric boundary is the key to revealing the interaction mechanism between the solar wind and the interstellar medium. The Helios ENA Rapid Mapper (HERMA) is a pre-research project for a new ENA detection concept and technical principle, which is designed to provide technical support for refined detection with its advantages of wide energy range coverage and high spatial resolution. To verify the high spatiote…

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astro-ph.GA

Intermittency in the Multiphase ISM --- II. Non-Gaussian Dust Polarization and Foreground Variance

Yue Hu

Interstellar turbulence produces non-Gaussian polarized Galactic dust emission whose higher-order statistics depend on thermal phase and turbulent forcing. We synthesize optically thin dust polarization from three thermally multiphase diffuse interstellar medium (ISM) simulations with compressive, mixed, and solenoidal forcing. We characterize the resulting non-Gaussian structure in the warm, unstable, and cold phases using $E$- and $B$-mode spectra, one-point distributions, scale-dependent incr…

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astro-ph.EPastro-ph.IM

Ultraviolet Reflected-Light Spectroscopy of Modern Earth Analogs with Starshade Observations

Zahra Ahmed, Stuart Shaklan, Mario Damiano, Armen Tokadjian, Edward W. Schwieterman, Simone D'Amico

Characterizing rocky, habitable zone planets in reflected light is a key science objective for future direct imaging missions, and the ultraviolet (UV) is uniquely suited for supporting the characterization of Earth-like atmospheres. The Hartley-Huggins ozone band at $0.25 ~μ\mathrm{m}$ remains detectable at low spectral resolution down to $0.1\%$ PAL $\mathrm{O}_2$, providing a sensitive proxy for oxygen-bearing chemistry even for Proterozoic-like atmospheres where the visible and near-infrared…

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astro-ph.GA

Untangling Similarities and Differences in Star Formation Histories Across Cosmological Simulations

Alicia M. Savelli, Matthew A. Kustec, Joshua S. Speagle, Kartheik G. Iyer, Eshal Ahmed, Zehao Peng, Norman Murray, Cissy Kuang et al.

How galaxies assemble depends on processes ranging from small-scale baryonic physics to large-scale cosmological assembly, which are difficult to disentangle with observations alone. Using $\sim$63,000 simulated galaxies from seven cosmological simulations spanning hydrodynamical, semi-analytic, and semi-empirical models, we explore how specific star formation histories (sSFHs) vary across modelling assumptions. Using non-linear dimensionality reduction (UMAP), we find that sSFH shape variation…

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astro-ph.GA

Intermittency in the Multiphase ISM --- I. Extreme Density, Velocity, and Magnetic Fluctuations

Yue Hu

Intermittency is a fundamental property of astrophysical turbulence because it concentrates strong gradients, dissipation, and transport into rare, localized structures. In the multiphase interstellar medium (ISM), turbulent driving is especially important because the balance between compressive and solenoidal motions can regulate how extreme fluctuations are distributed among thermal phases. Yet conventional increment statistics quantify intermittency without identifying the structures that hos…

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astro-ph.IMastro-ph.SR

Graph Learning with Multiplicative Aggregation for Solar Filament Fragment Association Modeling in Full-disk H$α$ Images

GaoFei Zhu, GangHua Lin, Xiao Yang, Suo Liu, Yu Liu, ZhiSheng Gao, Cheng Zeng

Solar filaments are prominent features in H$α$ observations. During their evolution, they often exhibit complex morphological and topological changes, which, due to line-of-sight projection effects, appear as fragmentation and merging. These phenomena make it difficult to reliably track solar filaments using automated methods, as the same structure may appear different over time. To address this issue, we formulate filament fragment association as a graph-based learning problem, where individual…

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astro-ph.EPastro-ph.IM

DEMOS. II. What the full Lupus demographics truly tell us about protoplanetary disc evolution

Lorenzo A. Malanga, Giovanni P. Rosotti, Giuseppe Lodato, Alice Somigliana, Benoît Tabone, Rossella Anania, Carlo F. Manara, Leonardo Testi et al.

Assessing whether disc evolution is driven by viscosity or MHD winds is crucial to determine the conditions in which planets form. The rich statistical information encoded in nearby star-forming regions provides an excellent opportunity to probe disc evolution. In this paper, we apply the Bayesian inference tool DEMOS, designed to exploit the statistical properties of disc populations and infer initial conditions and model parameters, to the Lupus disc population. We consider the observed distri…

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astro-ph.HE

Discovery of 51 pulsars in a reanalysis of the Green Bank North Celestial Cap Survey and a revised pulsar census

R. Sengar, L. Vleeschower, D. L. Kaplan, G. Y. Agazie, M. Bailes, A. Cassity, H. T. Cromartie, M. E. Decesar et al.

We present results from a reanalysis of the Green Bank North Celestial Cap (GBNCC) survey, conducted at 350 MHz with the Green Bank Telescope between 2009 and 2020, covering the sky with declinations $δ>-40^\circ$. We searched the survey data using an FFT-based periodicity search, with candidate selection extending to very low spectral signal-to-noise ratios and summing up to 32 harmonics. From the 60 promising candidates identified in this search, we confirmed 51 new pulsars using the Green ban…

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astro-ph.GA

Physical characteristics of the Galaxy defining the oscillation period of librating orbits near the OLR of the bar

A. M. Melnik, E. N. Podzolkova

We studied librating orbits of stars near the Outer Lindblad Resonance (OLR) of the bar using the angle-action variables of Hamiltonian dynamics. The librating orbits change the direction of their elongation relative to the major axis of the bar in a limited range of angles. To calculate orbits, we used the model of the Galaxy with an analytical bar which reproduces well the distributions of the observed stellar velocities along the Galactocentric distance R derived from the Gaia DR3 data. We co…

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astro-ph.EPastro-ph.IM

DEMOS I. A Bayesian inference framework to constrain disc evolution from observed demographics

Lorenzo A. Malanga, Giovanni P. Rosotti, Giuseppe Lodato, Benoît Tabone, Alice Somigliana, Leonardo Testi

The mechanism driving the evolution and dispersal of protoplanetary discs has a substantial impact on the theories of planet formation. To date, neither the viscous paradigm nor the MHD wind-driven framework have been ruled out by the observations. The statistical richness of the observed samples provides a unique opportunity to test evolutionary models through population synthesis. However, comparisons between models and observations are normally carried out by eye, and a more statistically rig…

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astro-ph.SRastro-ph.GAastro-ph.HE

An upper limit on Galactic OB+black hole binaries from SDSS-V

J. Müller-Horn, H. -W. Rix, S. Shahaf, B. Pennell, E. Zari, M. C. Ramírez-Tannus, A. Farah, R. Essick et al.

Binaries composed of a luminous OB star and a black hole (BH) are a key evolutionary link between massive stellar binaries and merging compact-object binaries, but only a handful are known and their occurrence fraction remains poorly constrained. We use multi-epoch spectroscopy from the SDSS-V Milky Way Mapper to place a first rigorous empirical upper limit on the fraction of Galactic massive ($\geq 10\,\mathrm{M}_\odot$) OB stars with a close BH companion, $f_\mathrm{BH}$. Radial-velocity (RV)…

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astro-ph.HEastro-ph.GA

Scaling Up: A Global Optical/X-ray Correlation For Reprocessing Across Black Hole Masses

Changhyun Cho, David M. Russell, Aaryan Sharma, Payaswini Saikia, Maria Cristina Baglio, Sandeep K. Rout, Yi-Jung Yang, Eleonora Caruso et al.

This study extends the optical/X-ray correlation from black hole low-mass X-ray binaries (XRBs) to active galactic nuclei (AGN), bridging scales from stellar-mass to supermassive black holes (SMBHs). In XRBs, optical emission predominantly originates from the thermal reprocessing of high-energy photons on the surface of the geometrically thin, optically thick accretion disk. The reprocessed optical luminosity follows a power-law relation of the form $L_{V} \propto L_{X}^β a$, with $β\sim 0.5$, w…

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astro-ph.HEastro-ph.GA

Scaling Up: A Global Optical/X-ray Correlation For Reprocessing Across Black Hole Masses

Changhyun Cho, David M. Russell, Aaryan Sharma, Payaswini Saikia, Maria Cristina Baglio, Kevin Alabarta, Sandeep K. Rout, Yi-Jung Yang et al.

This study extends the optical/X-ray correlation from black hole low-mass X-ray binaries (XRBs) to active galactic nuclei (AGN), bridging scales from stellar-mass to supermassive black holes (SMBHs). In XRBs, optical emission predominantly originates from the thermal reprocessing of high-energy photons on the surface of the geometrically thin, optically thick accretion disk. The reprocessed optical luminosity follows a power-law relation of the form $L_{V} \propto L_{X}^β a$, with $β\sim 0.5$, w…

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astro-ph.HE

Radio and Gamma-Ray Timing of a Newly Discovered Millisecond Pulsar

L. Vleeschower, R. Sengar, L. Nieder, C. J. Clark, D. L. Kaplan, A. Anumarlapudi, R. Girgaonkar, T. Thongmeearkom et al.

We report the discovery and timing of PSR J2147-3604, a fully recycled millisecond pulsar with a spin period of 3.2 ms, discovered in a reprocessing of the 350-MHz Green Bank North Celestial Cap (GBNCC) survey and later serendipitously confirmed by the MeerKAT TRAPUM UHF survey of Fermi-LAT unidentified sources. We followed up this pulsar with Murriyang/Parkes radio telescope and obtained a phase-connected timing solution spanning one year, revealing a 4.5-day binary orbit with very low eccentri…

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nucl-thastro-ph.HE

Universal relations for hybrid stars and their quark cores: a systematic scan of the quark-matter parameter space

J. P. Carlomagno, G. A. Contrera, A. G. Grunfeld, G. Lugones

Universal, equation-of-state (EOS) insensitive relations among the global properties of compact stars are well established for hadronic neutron stars and for self-bound strange stars. We ask whether analogous relations hold for the quark core of a hybrid star, and whether the core can be constrained from the surface. Describing quark matter with the three-flavor MIT bag model with repulsive vector interactions, matched to the hadronic DD2 EOS through a Maxwell construction, we scan the full $(B^…

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astro-ph.IM

Estimating the spectral resolution of a radio data cube from its noise properties

P. Serra, G. Mulas, K. M. Hess, P. Kamphuis, T. Westmeier, Y. Ascasibar, J. M. van der Hulst

We present a new method to estimate the spectral resolution of a radio data cube from its noise properties. We assume that the data cube is the result of the convolution of a spectrally-uncorrelated cube with a constant convolution kernel K. We demonstrate that K and the resolution, defined as K's integral, can be estimated thanks to the analytical relation between the autocorrelation of the noise spectra extracted from the cube and the power spectrum of the kernel. We discuss a number of algori…

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astro-ph.EP

High-resolution transmission spectroscopy of KELT-18b Metastable helium detection at 1083 nm

M. Chella, M. Monticelli, F. Biassoni, F. Borsa, M. Rainer, G. Guilluy, M. Basilicata, L. Cabona et al.

We present the first high-resolution transmission spectroscopy of the ultrahot Jupiter KELT-18b, probing its escaping atmosphere by analyzing a single transit obtained with the CARMENES spectrograph. Transmission spectroscopy and Doppler tomography were utilized to isolate the planetary signal. To mitigate contamination from the strong telluric OH lines overlapping the region of interest, two distinct data analysis procedures were applied: a standard Molecfit and OH-masking approach as well as a…

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astro-ph.SRastro-ph.GA

From Giant Envelopes to Rapidly Contracting Cores in Rotating Population III Stars from $500$ to $1000 \, M_\odot$

Devesh Nandal, John Chisholm, Daniel J. Whalen, Andreas A. C. Sander, Volker Bromm, Peixin Zhu, Lisa J. Kewley

Population III (Pop III) stars link the chemical enrichment of the early Universe to the formation of the first massive black holes, yet their evolution remains poorly understood at extreme masses. Using GENEC, we evolve rotating zero metallicity models from $500$ to $1000\,M_\odot$ at $v/v_{\rm crit}=0.1$ through core Si burning, and a $1000\,M_\odot$, $v/v_{\rm crit}=0.4$ model evolved through He exhaustion. In the fiducial $1000\,M_\odot$ model, convection and rotational transport carry fresh…

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astro-ph.GA

Magnetic field evolution in feedback-dominated galaxies

Yue Samuel Lu, Dušan Kereš, Philip F. Hopkins, Sam B. Ponnada

Over the last decade, magnetic fields (B-fields) have become a common ingredient in galaxy formation simulations. Although seemingly unimportant in matching observational constraints such as the $M_*-M_{\rm halo}$ relations, the B-field influences the circumgalactic medium (CGM) gas and determines cosmic ray (CR) propagation, making it an indispensable non-thermal component. Nevertheless, the intricate physics of B-fields, particularly how they evolve to the observed $μ$G-level field, remains la…

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astro-ph.COastro-ph.HEhep-ph

MeV dark matter decay forecasts for the COSI mission

Robin Anthony-Petersen, Orion Ning, Yu Watanabe, Benjamin R. Safdi, Maíra Dutra, Francesca Calore, Savitri Gallego, William Guan et al.

The decay of dark matter (DM) is a generic prediction of many particle physics models, producing distinctive monochromatic signatures in environments such as the Galactic halo. Searches for decaying DM in the elusive 'MeV gap' have remained conspicuously under-explored, despite well-motivated models including axion-like particles, sterile neutrinos, and hidden-sector scenarios predicting signatures in this energy range. The upcoming Compton Spectrometer and Imager (COSI) telescope will help brid…

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astro-ph.HEastro-ph.GAgr-qc

MRI Turbulence versus $α$-Viscosity in Circumbinary Disks: Implications for Gravitational-Wave Dephasing and Accretion Variability

Mudit Garg, Yan-Fei Jiang

Our understanding of gas torques on massive black hole binaries (MBHBs) relies on hydrodynamical (HD) simulations of circumbinary disks (CBDs) in which an $α$-viscosity models angular momentum transport. However, CBDs around MBHBs near merger are hot, magnetized plasmas where transport is driven by magnetohydrodynamical (MHD) turbulence sustained by the magnetorotational instability (MRI). We test how well an $α$-viscosity captures MRI turbulence with 3D global Athena++ simulations of a locally…

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astro-ph.COastro-ph.GA

Interpreting the stacked kinetic SZ signal II: the degeneracy between satellite galaxies and baryonic feedback

Lurdes Ondaro-Mallea, Boryana Hadzhiyska, Raul E. Angulo

The kinetic Sunyaev-Zel'dovich (kSZ) signal stacked around a galaxy sample traces the gas around halos and is a powerful probe of baryonic feedback. Its interpretation, however, depends on the satellite galaxies in the sample. Using the FLAMINGO hydrodynamical simulations and DESI-like samples of luminous red galaxies (LRGs), bright galaxies survey (BGS), and emission-line galaxies (ELGs), we show that satellites and feedback have similar effects: both suppress the small-scale signal. This degen…

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astro-ph.COastro-ph.IMphysics.data-anstat.APstat.ME

Beyond the Kullback--Leibler divergence: the likelihood-ratio distribution as a detectability measure

Amirhossein Samandar, Mikel Martin Barandiaran, Linn Htat Lu, Andrew H. Jaffe, Deyan P. Mihaylov, Glenn D. Starkman, Cynthia Trendafilova, Yashar Akrami et al.

The Kullback--Leibler (KL) divergence is the expectation value of the log-likelihood ratio between two specified models, evaluated with respect to one of the two models. It provides an average measure of the distinguishability of the models. We examine its connection to discovery potential and the accuracy of parameter estimates when one model represents a null hypothesis, and the alternative is a family of models characterized by one or more continuous parameters. For data drawn from a multivar…

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gr-qcastro-ph.HEhep-th

Vanishing Love Numbers of Kerr-Newman Black Holes

Sumanta Chakraborty, Takuya Katagiri, Paolo Pani, Jun-Xi Shi

Tidal Love numbers characterize the conservative response of compact objects to external perturbations and provide a powerful probe of their nature. While the static Love numbers of Schwarzschild, Kerr, and Reissner--Nordström black holes remarkably vanish, the tidal response of a generic Kerr--Newman black hole has remained unexplored due to the intrinsic coupling between gravitational and electromagnetic perturbations. Exploiting a recent breakthrough in the separability of these perturbations…

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astro-ph.IM

OASIS: On-the-fly ASynchronous Image Stream classification -- Transformer-based models for the early detection of strongly lensed supernovae

Satadru Bag, Raoul Canameras, Sherry H. Suyu, Stefan Schuldt, Stefan Taubenberger, Irham Taufik Andika, Alejandra Melo

Time-domain surveys often produce asynchronous image sequences across irregular observation times and photometric bands. In many applications, predictions are needed after each new observation, particularly when transient sources must be identified early to trigger follow-up. Strongly lensed supernovae (LSNe), for which follow-up is particularly time-critical, provide a useful example. We formulate this setting as On-the-fly ASynchronous Image Stream (OASIS) classification and explore reusable t…

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