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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.SR

Benchmarking Machine Learning Emulators of Stellar Evolution for Precision Asteroseismology

Naomi Gluck, Earl P. Bellinger, Yan Liang, Ebraheem Farag, Nicholas Saunders, Selim Kalici, Christopher J. Lindsay, Sarbani Basu et al.

Fast and accurate stellar evolution emulators---surrogate models that approximate expensive simulation outputs with machine learning (ML)---are powerful tools for modern stellar characterization, hierarchical inference, and population synthesis. We analyze the grid density required for reliable emulation by training ML algorithms on main-sequence models with masses M=[0.7,1.2] solar masses. This range is challenging to emulate due to rapidly varying evolutionary behavior caused by the radiative-…

astro-ph.EP

POSEIDON III: The Aligned Orbit of the Hot Neptune Around the Hot Star WASP-195

Juan I. Espinoza-Retamal, Joshua N. Winn, Rafael Brahm, Luke B. Handley, Elise Koo, Caleb Lammers, Cristobal Petrovich, Guðmundur Stefánsson et al.

Stellar obliquities provide important clues as to the formation and migration histories of planetary systems, but measurements remain scarce for Neptune-mass planets, especially those orbiting hot stars (above the Kraft break). Here we present observations of the Rossiter-McLaughlin effect in the hot-star/hot-Neptune system WASP-195 ($T_{\rm eff}=6470\pm100$ K, $v\sin{i_\star}=10.5\pm1.1$ km s$^{-1}$) obtained with the Keck Planet Finder and NEID spectrographs. A joint analysis of these observat…

hep-phastro-ph.HE

Inelastic Dark Photon Dark Matter for the LUX-ZEPLIN High-Recoil Event and the Galactic Halo Gamma-Ray Excess

Kimiko Yamashita

We show that a single dark-photon dark matter framework can simultaneously account for two recently reported anomalies: the halo-like Galactic gamma-ray excess identified by Totani in 15 years of Fermi-LAT data, and the $E_{\rm nr}=248\pm23\,({\rm stat})\pm23\,({\rm sys})$ keV nuclear-recoil event of interest reported by the LUX-ZEPLIN Collaboration. The dark matter is a $U(1)_X$ dark photon $X$ with mass $m_X=420$ GeV, stabilized by a dark parity that forbids kinetic mixing with the Standard Mo…

hep-phastro-ph.HE

Inelastic Dark Photon Dark Matter for the LUX-ZEPLIN High-Recoil Event and the Galactic Halo Gamma-Ray Excess

Kimiko Yamashita

We show that a dark-photon dark matter framework can simultaneously account for two recently reported anomalies: the halo-like Galactic gamma-ray excess identified by Totani in 15 years of Fermi-LAT data, and the $E_{\rm nr}=248\pm23\,({\rm stat})\pm23\,({\rm sys})$ keV nuclear-recoil event of interest reported by the LUX-ZEPLIN Collaboration. The dark matter is a $U(1)_X$ dark photon $X$ with mass $m_X=420$ GeV, stabilized by a dark parity that forbids kinetic mixing with the Standard Model pho…

astro-ph.HEgr-qc

Magnetized accretion onto rapidly spinning binary black holes: mini-disk thermodynamics, magnetic transport, and dual jets

Luciano Combi, Manuela Campanelli, Sean M. Ressler, Alexander J. Dittmann, Federico Cattorini

Supermassive binary black holes embedded in gas-rich environments are promising multi-messenger sources for pulsar timing arrays and future space-borne gravitational-wave interferometers. Their electromagnetic emission is governed by nonlinear plasma dynamics around the binary and is expected to inherit variability associated with the orbital motion thereof. Because active galactic nuclei are intrinsically stochastic, identifying robust binary signatures requires predictive models that connect l…

astro-ph.HEgr-qc

Magnetized accretion onto rapidly spinning binary black holes: mini-disk thermodynamics, magnetic transport, and dual jets

Luciano Combi, Manuela Campanelli, Sean M. Ressler, Alexander J. Dittmann, Federico Cattorini

Supermassive binary black holes embedded in gas-rich environments are promising multi-messenger sources for pulsar timing arrays and future space-borne gravitational-wave interferometers. Their electromagnetic emission is governed by nonlinear plasma dynamics around the binary and is expected to inherit variability associated with the orbital motion thereof. Because active galactic nuclei are intrinsically stochastic, identifying robust binary signatures requires predictive models that connect l…

astro-ph.HEastro-ph.SR

Vortex pinning and the elastic response of neutron-star crusts II. Non-axisymmetric loading and Magnus mountains

Elia Giliberti

Pinned superfluid vortices transmit a Magnus force to the neutron-star crust. A non-axisymmetric component of the superfluid-lattice lag can therefore support a persistent mass quadrupole. We calculate the l=m=2 response of self-gravitating, radially stratified spherical stars with SLy4 and BSk21 backgrounds, using a local microscopic pinning cap and a density-dependent Coulomb-lattice shear modulus. For a 1.4 M_sun star at 100 Hz, the equilibrium-compression maxima are epsilon=2.67x10^-9 (SLy4)…

astro-ph.IM

High performance Stingray

Eleonora Veronica Lai, Matteo Bachetti, Maura Pilia, Daniela Huppenkothen, Matteo Lucchini, Guglielmo Mastroserio, Hamza El Byad

X-ray astrophysical objects show variability on a wide range of timescales, i.e. from fractions of second to years. The open-source Python library stingray is able to perform time series analyses with a focus on high-energy astrophysics. Comprising the most commonly used Fourier analyses techniques, it also supports a range of additional extensions able to analyse pulsar data, simulate data sets and perform statistical modelling. With the latest release of the code, new Fourier methods and suppo…

astro-ph.EPastro-ph.IM

The Ultraviolet Spectrograph on ESA's Jupiter Icy Moons Explorer Mission (JUICE-UVS)

Kurt D. Retherford, Philippa M. Molyneux, Thomas K. Greathouse, Michael W. Davis, G. Randall Gladstone, Steven C. Persyn, Maarten H. Versteeg, Mary F. Araujo et al.

The Jupiter Icy Moons Explorer (JUICE) mission, led by ESA, has an Ultraviolet Spectrograph (JUICE-UVS) contributed by NASA and built at Southwest Research Institute. JUICE-UVS is designed to provide a diversity of measurements to further our understanding of the potential habitability of icy ocean worlds at Jupiter and to study Jupiter and the Jovian system as an archetype for gas giants. JUICE-UVS observes photons in the 50-204 nm wavelength range at moderate spectral and spatial resolution al…

astro-ph.HE

LHAASO-WCDA observed a $\sim$ 5 days TeV-delayed flaring event in blazar 1ES 1959+650

Zhen Cao, F. Aharonian, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, W. Bian et al.

We report a day-scale hard lag between GeV and TeV $γ$-ray emission from the HBL 1ES~1959+650 in early 2024. Since the LHAASO-WCDA real-time monitoring system began operation in late 2023, multiple TeV flares from this source have been triggered, including the 1st trigger flare on 2024 February 9. A Bayesian-block analysis of the WCDA light curve identifies three TeV flares in 2024. For the second triggered flare, a discrete cross-correlation analysis reveals a $>3\,σ$ correlation (relative to u…

astro-ph.HE

17 Yr of Magnetar Bursts Observed with the Fermi Gamma-ray Burst Monitor

Matt Godwin, Özge Keskin, Mustafa Demirer, Yi-Jing Yi, Lin Lin, Oliver J. Roberts, Ersin Göğüş, Yuki Kaneko et al.

The Fermi Gamma-ray Burst Monitor (GBM) has been in operation for over 17 years, during which it has observed more than a thousand bursts from soft gamma repeaters (SGRs), also known as magnetars. Serving as a laboratory for extreme physics, magnetars are a sub-family of neutron stars characterized by extreme magnetic field strength, observed through a combination of persistent and short transient emission across the electromagnetic spectrum. We present the comprehensive GBM catalog of SGR short…

astro-ph.IMastro-ph.HE

GRINTA: a new Probe of the Dynamic Universe

Lorenzo Natalucci, Philippe Laurent, Marica Branchesi, Mariateresa Fiocchi, Lorraine Hanlon, J. Miguel Mas-Hesse, Aline Meuris, Paul 'O Brien et al.

Recent observations of the transient sky at all wavelengths are increasingly revealing the importance of the multi-messenger and multi-wavelength approach. The GRINTA (Gamma-Ray INternational Transient Array Observatory) mission, proposed for launch around the middle of the next decade, is conceived as a small mission with good sensitivity, excellent angular resolution and fast follow-up capability for studying transient sources at timescales from ms to hours, at the same time ensuring optimal i…

hep-phastro-ph.HE

Sub-TeV Singlino Dark Matter in light from Sagittarius A$^\ast$ and LUX-ZEPLIN Nuclear-Recoil Event

Utpal Chattopadhyay, Debottam Das, Rahul Puri, Joydeep Roy

We investigate the impact of a dark matter density spike surrounding the Milky Way's supermassive black hole (SMBH) on the detectability of Singlino-dominated neutralino dark matter within the Next-to-Minimal Supersymmetric Standard Model (NMSSM). Similar density enhancements, or mini-spikes, around stellar-mass black holes (sBHs), have also been considered. Such a dark matter (DM) candidate typically produces weak indirect detection signals in conventional dark matter halos. Additionally, a Sin…

cs.LGastro-ph.IM

Do Tabular Foundation Models Know Physics? Contamination, Units, and the Deterministic Limit

Wassim Tenachi, Yashar Hezaveh, Laurence Perreault Levasseur, Pierre-Luc Bacon

Tabular foundation models (TFMs) learn to fill in tables the way language models fill in text, and tables are arguably the format in which most physical measurement arrives. Did they learn any physics in the process? They are Bayesian by construction, so the question is what their prior contains. We probe it directly, evaluating four of them (TabPFN-3, TabICLv2, TabDPT and Real-TabPFN-2.5) against six baselines on datasets sampled from 316 physical equations, in and out of domain. TFMs dominate,…

astro-ph.COastro-ph.GA

Gravitational Imprints of Axion Clouds on Black-Hole Orbital Dynamics

J. Ruz, V. Mungai, F. Kühnel, C. Köhn, E. Stamou, J. K. Vogel, B. Guichard

Black holes of primordial or astrophysical origin immersed in axion dark matter provide a natural laboratory for exploring the interplay between compact objects and ultralight scalar fields. While previous studies have primarily focused on superradiance and horizon-scale phenomena, the gravitational response of the surrounding axion distribution has received comparatively little attention. We investigate the dynamics of particles orbiting Schwarzschild and Kerr primordial black holes embedded in…

astro-ph.HEgr-qc

An Exact Engine for Black-Hole Jets

Yu Wang

For fifty years the Blandford--Znajek mechanism has been a mechanism and not an exact solution: force-free electrodynamics on a prescribed metric, with the jet's own field carrying no weight. Here that field gravitates. A split monopole weighs as much as a magnetic monopole, so its self-gravity is the magnetic Reissner--Nordström geometry; two copies glued across an equatorial current sheet put hole, disk and jet-driving flux into one spacetime, and force-free plasma makes a magnetosphere of it.…

astro-ph.EPastro-ph.SR

Revisiting orbital recurrence in the dimmings of Boyajian's star (KIC~8462852)

Hector Socas-Navarro

KIC~8462852 (Boyajian's star) shows deep, asymmetric, and highly irregular dimming events with no simple repetition pattern. A symmetric 1.1\% transit detected by \emph{TESS} in 2019 has been interpreted as a possible giant planet or brown dwarf, while the irregular dips are generally attributed to transiting dust from exocomets or planetesimal fragments. We test whether the broader dip families may nevertheless recur orbitally. Our scenario assumes a major disruption that produced fragments wit…

astro-ph.EP

The Hill sphere transits of Beta Pictoris c and the search for another 1981-like event

V. E. C. Bakker, M. A. Kenworthy, R. Stuik, K. Zwintz, T. Guillot, S. Vach, J. Wang, J. Kammerer et al.

Beta Pictoris is a young and nearby planetary system hosting an edge-on debris disk and at least three gas-giant planets. Their circumplanetary environments could host exomoons and rings, a detection of which would be highly informative for moon and planet formation theories. A photometric fluctuation of about 4% was seen towards Beta Pictoris in 1981, indicating the transit of dust in the system, which could be associated with the Hill spheres of the two inner planets. We search for the origin…

astro-ph.EPastro-ph.GA

Galactic tides in the Solar System within a non-axisymmetric Milky Way model adjusted to Gaia data

Alexandre Bougakov, Yassin Rany Khalil, Marc Fouchard, Melaine Saillenfest, Benoit Famaey, Paola Di Matteo, Misha Haywood

Context. Galactic tides are external differential forces acting on extended systems immersed in the Galactic potential. They play a key role in the dynamics of comets in the Oort cloud. Aims. We aim to establish the strength of Galactic tides from the non-axisymmetric potential of the Milky Way revealed by the Gaia mission, and how this strength evolves along the Galactic trajectory of the Solar System. Methods. We derived expressions for Galactic tide parameters independently of any simplified…

astro-ph.HE

Multiwavelength View of Black Hole X-ray Binary Swift J151857.0-572147

Manoj Mandal, Sachindra Naik, Souvik Manik, Sabyasachi Pal

We investigate multiwavelength timing and spectral properties of the newly discovered black hole X-ray binary Swift J151857.0-572147 during its 2024 outburst using observations from AstroSat, NuSTAR, NICER, Swift, and MeerKAT. The AstroSat/LAXPC20 power density spectrum reveals a $\sim$8 Hz low-frequency QPO with a quality factor of $\sim2.8$. The broadband X-ray spectrum of the source exhibits prominent reflection features, which are modeled to constrain the geometry and physical properties of…

astro-ph.HE

Multiwavelength View of Black Hole X-ray Binary Swift J151857.0-572147

Manoj Mandal, Sachindra Naik, Souvik Manik, Sabyasachi Pal

We investigate multiwavelength timing and spectral properties of the newly discovered black hole X-ray binary Swift J151857.0-572147 during its 2024 outburst using observations from AstroSat, NuSTAR, NICER, Swift, and MeerKAT. The AstroSat/LAXPC20 power density spectrum reveals a $\sim$8 Hz low-frequency QPO with a quality factor of $\sim2.8$. The broadband X-ray spectrum of the source exhibits prominent reflection features, which are modeled to constrain the geometry and physical properties of…

astro-ph.HE

Feeding The Little Monster: An Accreting Intermediate-Mass Black Hole In A Minor Merger Secondary Galaxy

Marko Mićić, Julia St. Pierre

We report the discovery of a luminous supersoft X-ray source associated with the secondary galaxy in a 10:1 minor merger at $z$=0.216. We identified the system in the 3D-HST survey and observed it serendipitously in more than 100 Chandra observations, providing a combined exposure of 6.6 Msec. The secondary galaxy ($\log$ (M$_*$/M$_\odot$)=8.24) exhibits X-ray emission detected exclusively below 2.0 keV, with no significant hard-band photons. Because the source is low-count, we characterize its…

astro-ph.GA

The Neutral Atomic Hydrogen in the solar neighborhood (NeAtHood) project I. Ghost in the shell: Neutral atomic hydrogen in the extended Orion nebula

J. D. Soler, H. Beuther, S. C. O. Glover, R. S. Klessen, J. Ott, M. Rugel, J. W. Teh, S. E. Clark et al.

The Orion Nebula is the nearest site of ongoing and recent high-mass star formation. It is a unique laboratory for studying the mass, energy, and momentum input from high-mass stars. We present 21-centimeter emission line observations that resolve for the first time the neutral atomic hydrogen (HI) gas in the extended Orion nebula (EON) at a resolution of one arcminute, which corresponds to a physical scale of 0.12 parsecs at the standard distance to the region. Our HI emission maps reveal an ex…

astro-ph.GAastro-ph.HE

Can diffuse X-rays be important in driving photoionisation in molecular clouds?

E. I. Makarenko, A. V. Ivlev, S. Bialy, X. Zheng, B. A. L. Gaches, P. Caselli, M. Padovani, M. C. H. Yeung et al.

The ionisation balance in molecular clouds is regulated by several ionising sources, including cosmic rays, X-rays, and ultraviolet radiation. Their relative importance depends on the local physical conditions and on the shielding column density. We compute the contribution of the large-scale diffuse X-ray radiation field to the ionisation in molecular clouds in the absence of strong local X-ray sources, such as young stars. Our goal is to quantify its significance relative to the Galactic cosmi…

hep-phastro-ph.HEhep-th

Dark Matter at the Kinematic Edge: Interpreting the 248 keV LZ Nuclear-Recoil Candidate

Mattia Di Mauro

The LUX-ZEPLIN (LZ) Collaboration recently reported one event consistent with a $248$ keV nuclear recoil in a $2.84$ tonne-year exposure, with a maximum local significance of $3.4σ$ and a global significance of $2.6σ$. We investigate whether the dark matter (DM)--nucleon interactions favored by this high-energy event can arise from particle DM models that simultaneously reproduce the observed relic abundance and satisfy indirect-detection constraints. Using the published LZ efficiency and operat…

hep-phastro-ph.HEhep-th

Dark Matter at the Kinematic Edge: Interpreting the 248 keV LZ Nuclear-Recoil Candidate

Mattia Di Mauro

The LUX-ZEPLIN (LZ) Collaboration recently reported one event consistent with a $248$ keV nuclear recoil in a $2.84$ tonne-year exposure, with a maximum local significance of $3.4σ$ and a global significance of $2.6σ$. We investigate whether the dark matter (DM)--nucleon interactions favored by this high-energy event can arise from particle DM models that simultaneously reproduce the observed relic abundance and satisfy indirect-detection constraints. Using the published LZ efficiency and operat…

astro-ph.EP

Drift-dominated dust evolution. A multiwavelength analysis of dust rings in CY Tau and DoAr25

Anastasia Topalidou, Nienke van der Marel, Paola Pinilla, Haochang Jiang, Osmar M. Guerra-Alvarado, Brodie J. Norfolk

Context. Protoplanetary disks are the birthplaces of planets, and understanding the distribution and evolution of dust within them is essential for tracing the early stages of planet formation. Aims. Following the DSHARP survey, we aim to constrain the radial distribution of the dust surface density and the maximum emitting grain size in the disks of CY Tau and DoAr 25 and assess the relative importance of dust trapping and radial drift in shaping the dust population in disks. Methods. We presen…

astro-ph.IMastro-ph.EPastro-ph.SR

3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper III. Key Scientific Mission: Exoplanet Science with a Coronagraph

Juhan Kim, Sang Hyun Lee, Yong-Woo Kang, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang et al.

This volume defines the exoplanet science program enabled by the dedicated high-contrast coronagraph in the baseline science payload of the 3.5-meter Segmented-Mirror Robotic Space Telescope. The observatory architecture incorporates the optical interfaces, wavefront sensing and control, pointing stability, and operations software required for coronagraphic observations from the outset. The observing strategy gives priority to the nearest stellar systems because they provide the most accessible…

astro-ph.IM

3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper II. Key Scientific Mission: Wide-Field Cosmology and Galaxy Evolution

Juhan Kim, Yong-Woo Kang, Sang Hyun Lee, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang et al.

The 3.5-meter Segmented-Mirror Robotic Space Telescope uses an image slicer for all spectroscopic observations. The planning baseline uses $R \simeq 1000$ for the wide survey and retains selectable $R \simeq 5000$ bands for precision line measurements. The central science case is a dense emission-line galaxy redshift survey for baryon acoustic oscillations and redshift-space distortions. Supernova and quasar programs exploit the stability, multiplexing, and repeatability of space operations. The…

astro-ph.IM

3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper I. Overall Architecture and Scientific Mission

Yong-Woo Kang, Sang Hyun Lee, Juhan Kim, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang et al.

A 3.5-meter segmented-mirror robotic space telescope is under study as a space-based observatory for precision astrophysical observations and rapid-response transient astronomy in the 0.2-1.5 micron wavelength range. The telescope adopts a Cassegrain optical configuration optimized to deliver diffraction-limited performance across a wide, flat focal plane, achieving a Strehl ratio greater than 0.8 at 633 nm. The proposed scientific payload includes a Wide-field Camera (WC), a spectroscopic instr…