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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.GAastro-ph.SR

Local Interstellar Flow Parameters from the First Intersection of IMAP-Lo's Parameter Tubes

Nathan A. Schwadron, Mitchell M. Shen, Fatemeh Rahmanifard, Eberhard Moebius, Hafijul Islam, Jonathan S. Bower, Maciej Bzowski, Eric R. Christian et al.

The Sun's motion through the interstellar medium creates a flow of interstellar neutral (ISN) atoms through the heliosphere. ISN He, due to its high universal abundance and relatively low ionization rate, is the most abundant of the interstellar species near 1 au and ideal for flow parameter determination. The Interstellar Boundary Explorer (IBEX) measurements of ISN He flow parameters (speed, temperature, and direction) yielded a tube in 4D parameter space -- narrow in cross-section but highly…

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astro-ph.HE

4U 1538-52 in a Heartbeat: Broadband X-ray Spectral Properties from XMM-Newton and NuSTAR

C. M. Diez, S. Dupourqué, A. -L. Doherty, D. Dickson, A. Zainab, S. Martínez-Núñez, J. M. Torrejón, S. Guillot et al.

Galactic high-mass X-ray binaries (HMXBs) are important systems for studying accretion mechanisms onto compact objects and for investigating the complex stellar winds of massive stars. In particular, HMXBs hosting a neutron star allow us to reveal the structure of the accreted material in X-ray pulsars and consequently to investigate how matter behaves under extreme conditions of pressure and density. These are major scientific goals for XRISM and NewAthena. Here we report on the first out-of-ec…

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astro-ph.GA

VAPOLA - A multiyear, multiband polarization survey of AGNs and Sgr A* at millimeter wavelengths with ALMA II. Spectropolarimetric properties and their evolution from 2017 to 2023

Douglas Carlos, Ciriaco Goddi, Alejandro Mus, Nicola Marchili, Kazi L. J. Rygl, Ezequiel Albentosa-Ruíz, Iván Martí-Vidal, The Event Horizon Telescope Collaboration et al.

We present a systematic analysis of the spectropolarimetric properties of a sample of 39 active galactic nuclei and Sagittarius A* observed with the Atacama Large Millimeter/submillimeter Array during five VLBI campaigns between 2017 and 2023. We characterize the compact cores in total intensity and polarization, focusing on the behavior or the linear polarization fraction (LP), electric vector position angle (EVPA), and Faraday rotation measure (RM) over time and spectral domains. We investigat…

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astro-ph.GA

High-spectral-resolution Observations of the [S II] Emission-line Doublet in the Filamentary Nebula Surrounding NGC 1275

Benjamin Vigneron, Julie Hlavacek-Larrondo, Carter Lee Rhea, Christoph Pfrommer, Greg L. Bryan, Megan Donahue, Alastair Edge, Andrew Fabian et al.

We analyze new high-spectral resolution SITELLE observations (R = $λ/Δλ$ = 7000) of the filamentary nebula surrounding NGC 1275, central galaxy of the Perseus cluster. We present here analysis of the \sii$\lambda6716$ and \sii$\lambda6731$ emission line doublet, using its ratio to determine the electron density of the optically emitting filaments. We compare these measurements with electron densities derived from deep Chandra X-ray observations of the intra-cluster medium (ICM) to determine if a…

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astro-ph.IM

Sub-Pixel Calibration of CMOS Sensors for Precision Astrometry

M. Shao, I. Hahn

Many sources of systematic error are important to centroid the position of a star below the level of $10^{-4}$ of the FWHM of the stellar image. One of the more important sources of centroiding error is the imperfect position of the pixels in a focal plane array. In this paper, we discuss the calibration of pixel position of multiple commercial CMOS detectors. Focal plane arrays are semiconductor devices fabricated with 10's nanometer precision. However, the effective location of a pixel can be…

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astro-ph.IM

Enabling Quantitative Polarimetry for Keck/NIRC2: Preliminary Mueller Matrix Model Calibration

Manxuan Zhang, Briley L. Lewis, Maxwell A. Millar-Blanchaer, Eduardo Marin, Jayke S. Nguyen, William Melby, Carlos Alvarez, Jaren N. Ashcraft et al.

The Keck/NIRC2 infrared imager was upgraded in 2025 with dual-beam polarimetric observing modes spanning approximately 1.1--4.1 microns (JHKL' bands). We present a preliminary JHK calibration of NIRC2 Polarimetry using a wavelength-dependent Mueller matrix model of the Keck tertiary mirror (M3), half-wave plate (HWP), image rotator (IMR), downstream optics, and Wollaston prism. We constrain the model downstream of M3 using dome flat sequences spanning ten HWP and nine IMR angles in each band. Al…

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astro-ph.IM

An open-source data processing pipeline for Keck / NIRC2-Polarimetry

Briley L. Lewis, Maxwell A. Millar-Blanchaer, Rebecca Zhang, Jayke Nguyen, Max Brodheim, Ashish Uhlmann

The Keck/NIRC2 infrared imager was recently upgraded with a new suite of polarimetric observing modes. This polarimetry upgrade (referred to as NIRC2-Pol) will open up a wide range of new astronomical studies, including investigations of exoplanets, the Galactic center, active galactic nuclei and the solar system. Astronomical polarimeters require sophisticated data reduction, especially for quantitative polarimetry requiring the use of a Mueller Matrix model for instrumental polarization calibr…

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astro-ph.HEphysics.space-ph

X-ray thread/Nonthermal Radio Filament associations: Evidence for Interstellar Magnetic Reconnection

Q. Daniel Wang

Nonthermal radio filaments (NTFs), first discovered at 20-centimeter wavelength more than four decades ago, are among the most enigmatic structures at the Galactic Center. They still defy a clear explanation. These striking narrow features trace intense magnetic fields and often stand in bold contrast to the Galactic plane. Recent discoveries have revealed surprising associations: some NTFs align well with X-ray threads that seem to exhibit Fe He-$α$ emission. Here, I present preliminary results…

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astro-ph.EP

The Enceladian crater production function

E. W. Wong, S. C. Werner, M. R. Kirchoff, R. Brasser

Interpreting Enceladus's past and present surface history and interior state remains challenging, owing to uncertain prescription of its impact bombardment history and limited interpretation of its crater statistics. Further progress in understanding its evolutionary history can be achieved with an improved crater chronology model and a thorough assessment of Enceladus's surface. Here we present the first step in the form of a comprehensive, global crater catalogue with geomorphology survey for…

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

Mixing stochasticity relinquishes evidence for magnetorotational hypernovae

Anmol Aggarwal, Ralph Schoenrich

A recent work claimed by fitting the observed elemental abundance pattern of a halo star with the total yields from single super-/hypernova events that only a magnetorotational hypernova event (a very energetic supernova event that also produces r-process elements) could be the source of the observed abundances. Here, we show that the star's peculiar abundance pattern is better fitted within the framework of mixing stochasticity with yields from a normal core collapse supernova (ccSN; Energy$_{\…

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astro-ph.SR

JWST/NIRSpec Spectra for Three Ultracool Brown Dwarfs Detected in Extragalactic Surveys: Further Evidence for Phosphine Absorption

Kevin N. Hainline, Samuel A. Beiler, Adam J. Burgasser, Evan S. Chen, Jakob M. Helton, Jarron Leisenring, Brittany E. Miles, Mark S. Marley et al.

We present JWST NIRSpec prism spectra for three ultracool brown dwarfs discovered in extragalactic survey data, two from the JWST Advanced Deep Extragalactic Survey (JADES), and one from Public Release IMaging for Extragalactic Research (PRIMER) survey observed as part of the Mirage or Miracle (MoM) program. The spectra for these sources indicate that one is a T6 dwarf (JADES-GS-BD-11, T$_{\mathrm{eff}} = \sim 700$ K) and two are Y0-Y1 dwarfs (JADES-GS-BD-5, T$_{\mathrm{eff}} = \sim 400$ K, and…

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astro-ph.HEhep-ph

Unveiling Neutrino Nature with the Diffuse Supernova Background

Marco Manno, Pablo Martínez-Miravé, Irene Tamborra

The true nature of neutrinos--whether Dirac or Majorana--is a foundational, unresolved question. We demonstrate that the diffuse supernova neutrino background (DSNB) offers an untapped avenue to resolve this issue, provided neutrino magnetic moments are $\gtrsim 10^{-14}μ_B$. The intense magnetic fields characteristic of a subset of collapsing massive stars can trigger resonant chirality flips. This flavor conversion physics alters DSNB fluxes in measurable ways that depend on the neutrino natur…

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astro-ph.HEgr-qc

Controlling artificial surface heating in neutron star simulations: Application to hybrid equations of state

Georgios Doulis

The treatment of the stellar surface in binary neutron star simulations is crucial for the accuracy of the numerical evolution and the physical reliability of the predicted observables. Numerical artifacts associated with the treatment of steep gradients near the stellar surface can produce spurious heating during the inspiral, leading to an artificial increase of the internal energy and an unphysical expansion of the neutron star. In this work, we investigate the effectiveness of the entropy-ba…

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astro-ph.HEgr-qc

Controlling artificial surface heating in neutron star simulations: Application to hybrid equations of state

Georgios Doulis

The treatment of the stellar surface in binary neutron star simulations is crucial for the accuracy of the numerical evolution and the physical reliability of the predicted observables. Numerical artifacts associated with the treatment of steep gradients near the stellar surface can produce spurious heating during the inspiral, leading to an artificial increase of the internal energy and an unphysical expansion of the neutron star. In this work, we investigate the effectiveness of the entropy-ba…

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hep-phastro-ph.HE

Blazar Boosted Dark Matter in IceCube

Alberto M. Gago, Jaime Hoefken Zink, Joel Jones-Pérez, Gabriel D. Zapata

We study the sensitivity of IceCube to blazar-boosted dark matter in a fermionic dark matter model with a massive vector mediator coupling to quarks. To this aim, we compute the diffuse flux arising from a sample of 324 blazars with proton spectra inferred from multiwavelength observations, adopting conservative dark matter spike profiles around the central supermassive black holes and consistently accounting for attenuation effects during propagation through the Earth. The dark matter-nucleon s…

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astro-ph.HE

Cosmic Ray Diffusion and the Origin of Very High Energy Gamma-Ray Emission in Young Massive Stellar Clusters

Lucas Barreto-Mota, Elisabete M. de Gouveia Dal Pino, Gaetano Di Marco, Rafael Alves Batista, Stela Adduci Faria

The search for Galactic sources capable of accelerating cosmic rays (CRs) to PeV energies has advanced significantly in recent years. High-energy observatories such as LHAASO have detected extended gamma-ray halos around several sources, suggesting that CRs escape their acceleration sites through anomalously slow diffusion. Theoretical studies propose that magnetic mirror diffusion combined with pitch-angle scattering in turbulent flow can naturally suppress CR transport. Here, we first show how…

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astro-ph.GA

ATLAS. IV. A JWST+MUSE Demographic Study of Ly$α$ Profiles in Little Red Dots

Yuta Kageura, Masami Ouchi, Hiroto Yanagisawa, Makoto Ando, Yuichi Harikane, Tomokazu Kiyota, Minami Nakane, Yoshiaki Ono et al.

We present an initial demographic study of Ly$α$ profiles in little red dots (LRDs) at $z=3$--9 using $R\sim1000$--4000 spectroscopy. Our sample consists of 8 LRDs observed in the VLT/MUSE Deep and Wide surveys and 23 LRDs observed with JWST/NIRSpec grating spectroscopy from JADES, CANUCS, and GO programs including SPURS. We identify Ly$α$ emission in 5 MUSE LRDs and 9 JWST LRDs. Only two of them exhibit broad Ly$α$ emission (FWHM $>1000\ \mathrm{km\ s^{-1}}$), both reported previously. The othe…

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astro-ph.EP

Hydrogen Engulfment into Sub-Neptune Cores through Magma Ocean Convective Surface Renewal

Edward D. Young

A convective surface renewal explanation for ingassing of hydrogen from H2-rich envelopes into molten cores of growing planets is presented, with particular application to sub-Neptunes. The ingassing of hydrogen occurs at a moving front comprising the upper boundary of the magma ocean that engulfs hydrogen from the envelope above as it moves. The mechanism of engulfment is surface renewal as the upper diffusive boundary layer is diluted by convection. Surface renewal results in ingassing even wh…

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astro-ph.GA

The deepest color-magnitude diagrams for the benchmark open cluster NGC 2437 from Gaia and VVVX

Tali Palma, Matías Gómez, Dante Minniti, Alan Montecinos, Nicholas J. G. Cross, Javier Alonso-García, Daniel Majaess, Bruno Dias et al.

Deep photometry of Galactic star clusters provides one of the most powerful tools for determining their physical properties. In particular, in low Galactic latitude regions that suffer from heavy extinction and crowding. NGC2437 is the most extended star cluster in the near-IR footprint of the VVV Extended Survey (VVVX), covering more than one degree on the sky. We aim to characterize its physical properties using Gaia DR3 in the optical and the VVVX in the near-IR. We use Gaia DR3 proper motion…

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astro-ph.GA

OH Line Detections in Southern Galaxies of the IRAS Revised Bright Galaxy Sample

Han Zhao, Zhongzu Wu, Bo Zhang, Timur Mufakharov, Yongjun Chen, Zhiqiang Shen, Yulia Sotnikova

We present a systematic study of OH main-line emission and absorption in 186 southern galaxies from the IRAS Revised Bright Galaxy Sample, using archival MeerKAT snapshot data. OH features are detected in 38 galaxies, including eight with OH maser emission (three new) and 30 showing OH absorption, mostly unreported previously. Four absorption systems exhibit weak OH emission superposed on strong absorption. OH-emitting regions are generally more compact than the associated radio continuum. Most…

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astro-ph.HEastro-ph.GA

XRISM reveals sloshing-driven gas motions in the core of Abell 2029

Yuusuke Uchida, Yuna Saito, Naomi Ota, Erwin T. Lau, Eric D. Miller, Tommaso Bartalesi, Stefano Ettori, Kotaro Fukushima et al.

We investigate the velocity structure of the intracluster medium (ICM) in the core of the relaxed cool-core cluster Abell 2029 using XRISM Resolve spectroscopy. We analyze combined XRISM Resolve observations and divide the central region into several subregions. To account for photon mixing caused by the XRISM point spread function, we perform a spatial-spectral mixing analysis. We detect an ordered line-of-sight bulk-velocity gradient across the cluster core: the northern regions are blueshifte…

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astro-ph.HEastro-ph.GA

XRISM reveals sloshing-driven gas motions in the core of Abell 2029

Yuusuke Uchida, Yuna Saito, Naomi Ota, Erwin T. Lau, Ming Sun, Eric D. Miller, Tommaso Bartalesi, Stefano Ettori et al.

We investigate the velocity structure of the intracluster medium (ICM) in the core of the relaxed cool-core cluster Abell 2029 using XRISM Resolve spectroscopy. We analyze combined XRISM Resolve observations and divide the central region into several subregions. To account for photon mixing caused by the XRISM point spread function, we perform a spatial-spectral mixing analysis. We detect an ordered line-of-sight bulk-velocity gradient across the cluster core: the northern regions are blueshifte…

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astro-ph.HE

Optical Spectroscopy of TeV-emitting BL Lac Candidates

Cassidy Metzger, Ryan C. Hickox, John R. Thorstensen

TeV-emitting BL Lacertae (BL Lac) blazars have important implications for the study of jet phenomenology, particle acceleration, and ultra high-energy cosmic ray production. They also allow for indirect studies of the extragalactic background light, cosmic magnetic fields, and axion-like particles. The upcoming Cherenkov Telescope Array (CTA), a ground-based gamma-ray observatory, will expand the observed TeV-emitting BL Lac population and enhance the aforementioned fields of study. However, rel…

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astro-ph.GAastro-ph.SR

The Galactic Centre G+0.633-0.0604 Molecular Cloud: A New Gold Mine for Astrochemistry

D. San Andrés, L. Colzi, V. M. Rivilla, M. Sanz-Novo, S. Martín, I. Jiménez-Serra, S. Zeng

Astrochemistry is living a golden age, with more than a quarter of the ~350 molecules in the current interstellar census having been detected over the last three years. One of the sources driving this progress is the G+0.693-0.027 cloud, located in the northern part of the Galactic Centre Sgr B2 complex. In this contribution, we present the astrochemical characterisation of G+0.633-0.0604, a newly discovered chemically rich molecular cloud at the southern edge of Sgr B2. With an inventory of >12…

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astro-ph.GAastro-ph.SR

The Galactic Centre G+0.633-0.0604 Molecular Cloud: A New Gold Mine for Astrochemistry

D. San Andrés, V. M. Rivilla, L. Colzi, M. Sanz-Novo, S. Martín, I. Jiménez-Serra, S. Zeng

Astrochemistry is living a golden age, with more than a quarter of the ~350 molecules in the current interstellar census having been detected over the last three years. One of the sources driving this progress is the G+0.693-0.027 cloud, located in the northern part of the Galactic Centre Sgr B2 complex. In this contribution, we present the astrochemical characterisation of G+0.633-0.0604, a newly discovered chemically rich molecular cloud at the southern edge of Sgr B2. With an inventory of >12…

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astro-ph.HEastro-ph.IM

The Evolution of the ACIS Contamination Layer on the Chandra X-ray Observatory from 2010 to 2026

Paul P. Plucinsky, Peter W. Ratzlaff, Akos Bogdan, Herman L. Marshall

The Chandra X-ray Observatory (CXO) was launched over 27 years ago and has been delivering spectacular science over the course of its mission. The Advanced CCD Imaging Spectrometer (ACIS) is the prime instrument on the satellite, conducting over 90% of the observations. The CCDs operate at a temperature of $-$120$^\circ$C and the optical blocking filter (OBF) in front of the CCDs is at a temperature of approximately $-$60$^\circ$C. The surface of the OBF has accumulated a layer of contamination…

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astro-ph.HE

Launching Jets in Tidal Disruption Events: Magnetic Flux Advection and Plasma Loading

Rin Oikawa, Yuri Sato

A tidal disruption event (TDE) occurs when a star approaches a black hole (BH) and is disrupted by its tidal forces. Although several hundred TDEs have been identified to date, only a small fraction are accompanied by relativistic jets. These jets are thought to be Poynting-flux-dominated outflows powered by the Blandford--Znajek (BZ) mechanism. However, the origin of the magnetic flux and plasma needed to power BZ jets remain unclear. In this Letter, we propose a scenario in which magnetic flux…

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astro-ph.SRastro-ph.GA

Magnetoacoustic Portals in Quiet-Sun Fluxtubes Revealed by Chromospheric Spectropolarimetry with SUNRISE III/SCIP

Takayoshi Oba, Yukio Katsukawa, Masahito Kubo, Yusuke Kawabata, Takuma Matsumoto, Ryohtaroh T. Ishikawa, Yoshihiro Naito, Toshifumi Shimizu et al.

Acoustic waves propagate into the chromosphere, contributing to energy transport and their dynamics. Their upward propagation is restricted to frequencies above the acoustic cutoff frequency. The magnetic field configuration plays a key role in determining whether acoustic waves can propagate upward because the cutoff frequency is reduced in regions where the field is inclined with respect to gravity, forming so-called magnetoacoustic portals. Previous studies linked magnetic fields and oscillat…

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physics.plasm-phastro-ph.SR

Physics of Circular Polarized Ion-Scale Waves in Hybrid Simulations of Alfvénic Fluctuations

Hai Yang Harry Qian, Trevor A. Bowen, Carlos A. Gonzalez, Nikos Sioulas, Alfred Mallet, Kristopher G. Klein, Daniel Verscharen, Stuart D. Bale et al.

Ion cyclotron waves (ICW) and fast magnetosonic/whistler waves (FMW) are fundamental electromagnetic modes at ion kinetic scales, yet their generation mechanisms and roles in plasma evolution remain poorly understood. We analyze a 2.5D hybrid simulation of broadband Alfvénic fluctuations, where the proton velocity distribution is modeled as a sum of two bi-Maxwellian components: a thermal core and a drifting beam. Using wavelet-based wave identification, bi-Maxwellian VDF fitting, and the PLUME…

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astro-ph.GA

A Reproducible Two-Boundary Kinematic Correction for Baryonic Rotation-Curve Reconstruction in an 84-Galaxy SPARC Benchmark

David C. Flynn

We present a reproducible computational validation and failure analysis of the empirical omega kinematic correction introduced by Flynn and Cannaliato (2025). The algorithm is deliberately minimal: one coefficient per galaxy is calculated from the innermost and outermost measured rotation-curve points and applied to the full observed radial profile before comparison with a baryonic reconstruction assembled from SPARC gas, disk, and bulge components. We preserve the predecessor's frozen 84-galaxy…

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