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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.IMastro-ph.EP

Automated Shape-Model-Based Astrometry of Phobos from Mars Express SRC Images

Wangxin Lai, Qingfeng Zhang, Rui Zhang, Kai Tang, Chunyu Ding, Zhan Li, Haipeng Wang

High-resolution spacecraft images provide important astrometric constraints for orbit refinement, but measurements of resolved bodies are often limited by labor-intensive control-point selection and the difficulty of achieving consistent reductions over large image archives. We present an automated shape-model-based astrometric pipeline for Phobos and apply it to Mars Express Super Resolution Channel (SRC) images. For each exposure, a synthetic image is rendered from a high-resolution 3D shape m…

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astro-ph.EPastro-ph.IM

Assessment of the 5 August 2026 Falcon 9 Upper-Stage Lunar Impact: Energetics, Crater Scaling, and Comparison with LRO Observations

Mavia Anjum

The objective of this study was to characterize the human-made object that impacted the Moon on 5 August 2026, to estimate the dimensions of the crater it produced, and to compare the estimates with the crater subsequently measured by the Lunar Reconnaissance Orbiter (LRO). The impactor was the discarded upper stage of a SpaceX Falcon 9 rocket, which struck the surface near Einstein crater at a velocity of 2.43 km/s. The kinetic energy and linear momentum of the impactor were calculated, and the…

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gr-qcastro-ph.HE

Extreme mass-ratio inspirals around rotating accelerating black holes

Xin-Dong Du, Tao Zhou, Wei Xiong, Tieguang Zi, Peng-Cheng Li

Extreme mass-ratio inspirals (EMRIs) can magnify small departures from Kerr dynamics into appreciable gravitational-wave phase shifts accumulated over many orbital cycles. We exploit this sensitivity to investigate the imprint of a rotating black hole's acceleration on an EMRI waveform. The spinning C metric poses two obstacles to the standard Kerr flux framework: the spacetime is not asymptotically flat, and the acceleration breaks the reflection symmetry that supports exactly equatorial circul…

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astro-ph.IMgr-qcstat.AP

Variational Bayesian Inference for the Spectral Structure of LISA Noise

Jianan Liu, Avi Vajpeyi, Renate Meyer, Jeung Eun Lee, Patricio Maturana-Russel

Estimating spectral density matrices for future space-based gravitational-wave detectors such as LISA is challenging due to the long duration of the data and the correlated instrumental noise across multiple time-delay interferometry channels. In this work, we investigate a specialized mean-field stochastic gradient variational Bayes (SGVB) procedure for fast posterior approximation in long-duration multivariate spectral density estimation. Based on the existing eigenbasis representation of the…

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astro-ph.GA

The Cosmic Ultraviolet Background at the Galactic Poles

Jayant Murthy, James Overduin, Raj Manas, Amit Pathak, Snehanshu Saha, Richard C. Henry

We have used archival GALEX data to separate the cosmic ultraviolet background at the Galactic Poles into two components: the dust scattered light and an offset. We have modeled the dust-scattered light using a single- scattering model finding 1 sigma limits of 0.54 -- 0.71 for the albedo (a) and 0.74 -- 0.83 for the phase function asymmetry factor (g) at 1530 Å and 0.66 -- 0.73 for a and 0.71 -- 0.77 for g at 2360 Å, that is, the grains are moderately reflective and highly forward-scattering. T…

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physics.plasm-phastro-ph.SR

Plasmon-polaritons in a rarefied nonrelativistic neutron gas

P. O. Kazinski, A. M. Trushchuk

The electromagnetic properties of a dilute unpolarized nonrelativistic neutron gas are described in the case when neutron-by-neutron scattering is negligible. The Gaussian (Maxwell-Boltzmann) and Fermi-Dirac one-particle density matrices for the neutron gas are considered, the typical space scale of variations of these density matrices being assumed to be much larger than the the typical space scale of variations of the electromagnetic field. The Green functions for the static effective Maxwell…

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astro-ph.IM

Modeling the technical specifications for future multi-object spectroscopy instrumentation

Ummee Tania Ahmed, Andrew Hopkins, Simon Ellis

We investigate a proof-of-concept code designed to model the functionality of current generation astronomical fiber positioner instruments. This code accommodates an arbitrary number of fiber probes and astronomical targets. To establish the prerequisites for future fiber positioning technologies, we conduct a systematic analysis of both the observational and instrumentation parameter space (such as target density, fiber density, and exclusion and patrol radius). The tool assesses the efficiency…

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cs.AIastro-ph.IM

A survey detection channel overrides the pixels in an astronomical foundation model, and biases tomographic mean redshifts

Ihor Kendiukhov

Foundation models for astronomy are trained on survey pixels together with the catalogue products derived from those pixels. Those catalogues are incomplete at a measurable rate, and a model trained on both inherits that incompleteness as a systematic. We audit AION-1, a 39-modality transformer trained on more than 200 million objects, using causal interventions on its inputs. Holding the image tokens byte-identical and editing only the survey segmentation map changes every quantity the model re…

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astro-ph.GA

[CII] as a global cold gas tracer in novel hydrodynamical simulations

Valentina P. Miranda, Patricia B. Tissera, Jorge González-López, Emanuel Sillero

[CII] emission is a powerful tool for studying the gas content in galaxies, especially at early stages of evolution. Given its low excitation potential, the [CII] 158 μm line is the main coolant of neutral gas in photodissociation regions and giant molecular clouds, hence a tracer of all phases of the interstellar medium. However, there is no consensus on what is the nature of the gas traced by this emission. We aim to provide insights into the physics of the [CII] emission and predictions for f…

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astro-ph.GAastro-ph.IM

AstroBind: Machine learning prediction of binding energy distributions on interstellar water ice from geometric surface descriptors

Aneesa Ahmad, Catherine Walsh

Binding energies on amorphous solid water regulate molecular desorption in molecular clouds and protoplanetary disks, but computing them from first principles across the heterogeneous binding sites of disordered ice surfaces is computationally prohibitive. We aim to develop a rapid, interpretable method for predicting binding energies on amorphous solid water that captures surface heterogeneity without requiring explicit electronic-structure calculations. We trained a machine-learning model usin…

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astro-ph.SRcs.AIcs.LG

Discovering Dual-Origin Slow Wind from Solar Orbiter with Self-Supervised Contrastive Learning

Henry Han, Jorge Yero Salazar

Whether the slow solar wind originates from one coronal source or two distinct channels remains a central open question in heliophysics. Resolving this requires unsupervised separation of two populations that arrive at nearly the same bulk speed and differ mainly in heavy-ion composition. We present Solar-CDC, a self-supervised contrastive deep clustering (CDC) framework that maps plasma observables to a latent space via a Transformer encoder, optimizes a triplet margin loss, and updates pseudo-…

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astro-ph.HEgr-qc

The imprint of individual neutron star spins on ejecta, $r$-process nucleosynthesis, and kilonovae in binary neutron star mergers

Beyhan Karakas, Rahime Matur, David Radice, Roland Haas, Maximilian Ruffert

To leading order, the gravitational-wave (GW) signal from binary neutron stars depends on the individual spins, $χ_1$ and $χ_2$, only through the effective spin parameter $χ_{\rm eff}$. We present the first systematic investigation of individual-spin effects on ejecta, $r$-process nucleosynthesis, and kilonova emission, including comparisons at fixed total mass, mass ratio and $χ_{\rm eff}$. We use numerical relativity ejecta from three total mass regimes with the finite-temperature, composition…

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astro-ph.HEastro-ph.GAastro-ph.SR

Particle acceleration and non-thermal broadband spectrum of extended shocked outflows in black hole binary V4641 Sgr - a galactic pevatron

Andrei Bykov, Sergei Osipov, Vadim Romansky, Eugene Churazov, Ildar Khabibullin

Stellar mass black holes accreting at a super-Eddington rate produce strong outflows and non-thermal radiation up to PeV energy. Recently, very high energy (VHE) emission was discovered from the environment of the galactic microquasar V4641 Sgr, which is known to experience super-Eddington outbursts. We present MHD simulations supplemented with a nonlinear kinetic Monte Carlo model that reproduces the observed radio, X-ray, and gamma-ray emission from the region over tens of parsecs surrounding…

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astro-ph.HE

Correlation of gamma-ray and optical variability of BL~Lacertae during the period of high blazar activity

Marina S. Butuzova, Mark A. Gorbachev

Investigating the correlation of flux variability in blazars across multiple spectral bands provides a key tool for constraining emission mechanisms and jet physical parameters. We study the gamma-ray and optical variability correlation of BL Lacertae on timescales of about 1 day during September 2022, when the source was within the TESS field of view, and over a longer period (April 2022 - September 2023) encompassing its gamma-ray flare, which finishes the series of flares during the high-acti…

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astro-ph.HEphysics.plasm-ph

Pair Discharges and Radio Emission from Millisecond-Pulsar and White-Dwarf Magnetospheres

Tuomo Salmi, Joonas Nättilä

Coherent radio emission is observed from compact astrophysical objects with relatively weak magnetic fields, including millisecond pulsars and white dwarfs, the latter being proposed as possible sources of long-period radio transients. In such environments, the standard pair discharge mechanism---driven by curvature radiation and one-photon pair production---can fail because the low magnetic field strength suppresses photon conversion. We analyze a discharge mechanism that operates efficiently i…

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astro-ph.HEgr-qc

Finite-Solid-Angle Boltzmann Radiation Transport on Dynamical Spacetimes in AthenaK

Hengrui Zhu, Alexander J. Dittmann, Lizhong Zhang, James M. Stone, Eduardo Mario Gutierrez, David Radice

We extend the finite-solid-angle general relativistic radiation transport method of C. J. White et al. (2023) to time-dependent spacetimes represented in ADM form. This Valencia-type solver retains the angular transport and local implicit matter coupling of the original HARM-type solver, but replaces its time-independent Kerr--Schild tetrad and conserved-variable normalization with an Eulerian formulation. A Cholesky-gauge spatial tetrad makes the frame and its derivatives algebraic functions of…

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astro-ph.GAastro-ph.SR

MIAO-ALMA: Shocks and Protostellar Outflows in 70 $μ$m-dark clumps with $L/M$ $<$ 1 $L_{\odot}$/$M_{\odot}$

Shuting Lin, Siyi Feng, Junzhi Wang, Shanghuo Li, Dan Miao, Zhi-Yu Zhang, Sheng-Yuan Liu, Nami Sakai et al.

To investigate the initial conditions of high-mass star-forming regions, we use SiO (2-1) emission to trace early shock-related kinematics toward sixteen 70 $μ$m-dark and massive clumps with luminosity-to-mass ratios ($L/M$) $ $ 2 km s$^{-1}$) SiO (2-1) features not associated with outflows driven by clearly identified protostars. Lacking coincident 3 mm dust continuum cores, their origins may be young outflows from undetected low-mass protostars, dissipating shocks, cloud-cloud collisions, or p…

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astro-ph.HE

Discovery of an Extremely Luminous Sporadic Radio Pulsar

Fengqiu Adam Dong, Robert Main, Jackson D. Taylor, Shion Andrew, Alyssa Cassity, Shami Chatterjee, Alice P. Curtin, Emmanuel Fonseca et al.

We have discovered PSR J2108+5055, an extremely luminous but sporadic mode-changing rotating radio transient (RRAT), with a period of 0.495 s using the Canadian Hydrogen Intensity Mapping Experiment/Fast Radio Burst instrument (CHIME/FRB). We show that the brightest pulse from PSR J2108+5055 has a flux density of 3.1+/-1.0 kJy, corresponding to a spectral luminosity of (7.5+/-2.3)x10^23 erg s^-1 Hz^-1, assuming a dispersion-measure-derived distance of 1.6+/-0.3 kpc. We place an upper limit on th…

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astro-ph.SR

WISE J005128.08+645651.7: An enigmatic R Coronae Borealis star

J. Budaj, K. Bernhard, I. Hubeny

Context. R Coronae Borealis (RCB) stars are hydrogen-deficient and carbon-rich (HdC) supergiants that likely originate from a merger of two white dwarfs. As such they are not expected to be members of close binary systems, in agreement with current observations. Aims. We test the above hypothesis and search for eclipses of RCB stars that could be due to a companion. Methods. We exploited old archival photometric data from Harvard photographic plates (DASCH) as well as modern-era photometric surv…

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astro-ph.HEphysics.plasm-ph

Pair Discharges and Radio Emission from Pulsar Magnetospheres

Joonas Nättilä, Tuomo Salmi

Radio pulsars can power their coherent radio emission through intermittent plasma discharges in magnetospheric gaps. The nonlinear coupling between particle acceleration, quantum electrodynamic (QED) processes, and electric field screening remains difficult to model self-consistently. We present an analytical concurrency model and first-principles particle-in-cell (PIC) simulations of polar cap discharges. The model predicts limit-cycle behavior where the electric field and plasma density oscill…

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astro-ph.SR

CPD-82 291: Multi-sector TESS Photometry and SED Analysis of an Active Eclipsing Binary

Volkan Bakış, Gökhan Yücel

We present a multi-sector $TESS$ photometric and spectral energy distribution analysis of the eclipsing binary CPD--82~291 (RX~J0853.1--8244). Eight $TESS$ sectors reveal well-defined eclipses and substantial, changing out-of-eclipse modulation. The asymmetries are reproduced by different surface-brightness configurations at different epochs, consistent with strong and evolving stellar activity, although the fitted circular regions are not unique maps of individual starspots. A detached-binary l…

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astro-ph.GA

Indirect evidence of the $2175\,\mathring{\mathrm{A}}$ extinction bump within the dusty torus of SDSS J141945.50+524648.0

Ze Li, Gaoyang Chen, Qifan Cui, Zheng Cai, Jianzhen Chen, Zhijian Luo, Chenggang Shu, Fengwu Sun et al.

We present a multi-wavelength study of the quasar SDSS J141945.50$+$524648.0 ($z=1.1599$), a member of the newly identified population of quasar-associated $2175\,\mathring{\mathrm{A}}$ dust absorbers. Utilizing JWST/NIRCam observations from the SAPPHIRES survey and archival data, we analyze the prominent $2175\,\mathring{\mathrm{A}}$ extinction bump detected in this object. The bump parameters are highly consistent with the Milky Way extinction curve, implying similar dust properties. Spectral…

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astro-ph.GA

Constraining the Inner Dark-Matter Slope of Sculptor: A Comparative Analysis of Dynamical Methods

Rishi Sanjeev

The core-cusp problem is a discrepancy between simulations and observations of the slopes of inner dark matter density profiles. The two-population estimator, separating dwarf spheroidals into metallicity-split subcomponents, is a standard method to break the mass-anisotropy degeneracy. Four dynamical methods are applied to the 1339-star Tolstoy et al. (2023) VLT/FLAMES Sculptor catalog: spherical Jeans, GravSphere, the Walker and Penarrubia (2011) two-population estimator, and a continuous $f(J…

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astro-ph.EPcond-mat.mtrl-sci

A surviving pink spinel records an early aluminous melt on the ureilite parent body

Yaozhu Li, Phil J. A. McCausland, Roberta L. Flemming, Noriko T. Kita, Carsten Detlefs

Ureilites are ultramafic achondrites interpreted as fragments of a differentiated parent body, yet their origin and evolution remain debated because textural equilibrium coexists with chemically primitive compositions. Here we report mineralogical, isotopic, and microstructural observations from polymict ureilite Elephant Moraine (EET) 87720. The sample contains unusually magnesian olivine (Mg# up to 98.7), Ca-poor pyroxene (Wo as low as 1.0), and rare coarse-grained pink aluminous spinel contai…

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astro-ph.COastro-ph.IM

Simulation Tests of PSF Modeling for Cosmic Shear with the Vera C. Rubin Observatory

Claire-Alice Hébert, Erin S. Sheldon, Tianqing Zhang, Joachim Harnois-Déraps, Mike Jarvis, the LSST Dark Energy Science Collaboration

Exceptional control of systematic effects is required in order to achieve unbiased cosmic shear two-point correlation function measurements with the next generation of galaxy imaging surveys, such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). One critical challenge is accurately modeling the point-spread function (PSF), as errors in PSF estimation can introduce spatially correlated biases in galaxy shape measurements. The LSST Science Pipelines, which will be used to p…

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astro-ph.HE

Galactic Electron-Positron Annihilation Emission from X-Ray Binaries with Transient and Persistent Jets

Argen Gian Detoito, Henric Krawczynski

The Galactic Center exhibits a persistent 0.511 MeV emission characteristic of electron-positron annihilation. Various astrophysical sources may be responsible for supplying the positrons, yet their contributions with respect to the total annihilation rate is uncertain. X-ray binaries have historically been a primary candidate, possibly contributing a significant fraction of the Galactic positrons. X-ray binaries can produce positrons through the Blandford-Znajek mechanism, two-photon pair produ…

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gr-qcastro-ph.HEhep-th

Kerr-Newman and genuine Kerr black holes in the Bertotti-Robinson magnetic field

Hryhorii Ovcharenko, Jiri Podolsky

We present a spacetime that describes a rotating and charged black hole immersed in an external magnetic field. This exact solution to the Einstein-Maxwell equations has a surprisingly simple form which reduces to standard Kerr-Newman metric, and to the uniform Bertotti-Robinson magnetic universe. We show that the Kerr-BR solution presented in [Phys. Rev. Lett. {\bf 135}, 181401 (2025)] has a special charge, and we identify a genuine Kerr black hole without any charge, in the magnetic field. In…

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astro-ph.IM

Image persistence flagging for SPHEREx

Candice Fazar, C. Darren Dowell, Brendan P. Crill, Phil Korngut, Chi Nguyen, Howard Hui

Image persistence in HAWAII-2RG HgCdTe detectors has been observed by multiple parties. Also known as latent signal, this effect occurs when sensor images following an illumination show a decayed form of the illuminated image even though the source has been removed and the detector has been reset. Using data from an engineering grade detector array delivered for SPHEREx testing illuminated with a wide range of fluxes, we demonstrate an interpretation and a working model from which the decaying s…

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astro-ph.HEastro-ph.GAastro-ph.SR

When the stars don't align: Investigating inconsistencies in binary black hole formation across population synthesis codes

Alexandra G. Guerrero, Michael Zevin, Duncan B. Maclean, Katelyn Breivik, Carl L. Rodriguez, Max M. Briel, Daniel E. Holz

Binary population synthesis (BPS) codes are extremely useful tools for investigating both the end-to-end lives of binary stars as well as a myriad of astrophysical phenomena observed in the Universe. Given the widespread use of BPS in modern astrophysical research, it is imperative to systematically compare BPS codes across the spectrum of computational efficiency, flexibility, and physical realism to gauge their consistency and robustness. In this work, we perform BPS using three modern codes--…

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astro-ph.GA

Supernovae Ia ejecta velocities and host galaxy environments: the role of survey-selection effects

L. V. Barkhudaryan, A. A. Hakobyan, M. H. Gevorgyan, D. Kunth, G. A. Mamon, U. Burgaz, V. Adibekyan, Zh. R. Martirosyan et al.

The origin of the near-maximum-light Si II $λ$6355 velocity diversity among supernovae Ia (SNe Ia) remains uncertain. Previous studies have suggested that high-velocity (HV) and normal-velocity (NV) SNe Ia occupy systematically different host galaxy environments, implying differences in their progenitor populations. We re-examine this hypothesis using a sample of 354 nearby ($z\leq0.04$) spectroscopically normal SNe Ia, comprising 239 NV and 115 HV events, identified in targeted and untargeted s…

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