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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

Measuring Outflow Distances in NGC 5548 Using Absorption-Line Variability Diagnostics

Yaqi Chen, Zhicheng He, Guilin Liu

AGN-driven outflows serve as a key channel through which the energetic central engine influences host galaxy evolution. Among the physical properties of outflows, their radial distance from the galactic nucleus is particularly important for assessing AGN feedback. In this study, we investigate the UV outflow components in NGC 5548 by analyzing the variability of C IV absorption troughs in optical spectra obtained through multiple HST observations during 2013 and 2014. We construct a set of varia…

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astro-ph.GA

A RELHIC twin candidate near the galaxy M51

Qingze Chen, Jie Wang, Yingjie Jing, Chen Xu, Tiantian Liang, Zerui Liu, Zhipeng Hou, Yiwei Xu et al.

We report the discovery of a pair of H I clouds near M51 (NGC 5194) using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). These clouds have no optical counterparts and are potential candidates for Reionization-Limited H I Clouds (RELHICs). We search for compact H I sources in deep FEASTS observations using SoFiA and remove objects with optical counterparts through cross-matching with the DESI Legacy Imaging Surveys. The remaining candidates are modelled as hydrostatic H I struc…

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astro-ph.GA

Dissecting the multiple-component outflow in NGC 5548 with absorption-line Variability

Yaqi Chen, Zhicheng He, Guilin Liu

AGN-driven outflows are routinely invoked as a key agent of supermassive black holes to regulate the evolution of galaxies. The radial distance from the central engine is a crucial parameter for evaluating the impact of these outflows on the host galaxy. In this work, we estimate the radial distances of ultraviolet (UV) outflow components in NGC 5548 using the most up-to-date absorption-line variability method, combined with multi-epoch HST/COS spectroscopy from the 2014 AGN STORM campaign and a…

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astro-ph.HE

The Extended Ultrahigh-energy Gamma-Ray Emission in the Vicinity of PSR J2238+5903

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

We present a comprehensive analysis of the recently discovered TeV gamma-ray source, LHAASO J2238+5900. Based on data collected from the LHAASO, our fitting results suggest that the source is significantly extended with an angular extension of 0.54° \pm 0.01° and is spatially coincident with the pulsar PSR J2238+5903. Its spectrum is characterized by a power-law with a cutoff at 41.0\pm 3.5 TeV. Additionally, the source exhibits a significant signal of 7.9σabove 100 TeV, implying that it is a Pe…

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astro-ph.IM

GCR Spectra Reconstructed with Neutron Monitor Yield Function and Artificial Neural Networks: Comparison of Two Methods

Stepan Siruk, Vladislav Alekseev, Victor Kuzminov, Rustam Yulbarisov, Andrey Mayorov

We present a framework that reconstructs time-resolved galactic cosmic-ray (GCR) proton and helium energy spectra from the global neutron monitor network, providing data about GCR flux without direct satellite observations. Two methods are utilized and compared: a calibrated yield function plus force-field scheme and artificial neural networks trained on multi-station neutron monitor count rates coupled with heliophysical indices. The reconstructed spectral time series reproduce both large-scale…

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astro-ph.SRastro-ph.GA

HARPS Abundances with Korg I: 22 Element Abundances for 426 Red Giant Stars

Sarah E. Aquilina, Melissa Ness, Adam J. Wheeler, Sven Buder

Large stellar surveys have revealed the global abundance structure of the Milky Way, but small high-fidelity spectral samples offer a critical complement of nucleosynthetic depth. We aim to access the encoded information in an ensemble of abundances by leveraging highest-quality spectra. We used HARPS spectra (R=115,000) to determine (Teff, log(g), [M/H], vmic and vsini) and 22 element abundances (Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Fe, Ni, Zn, Sr, Y, Zr, Mo, Ba, La, Ce, Nd and Eu) for 426 red…

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astro-ph.GA

Accurate Extragalactic Magnetic Fields from Faraday Rotation with Optimal Dispersion Measure Estimators

Hilay Shah, Mark Krumholz, Naomi McClure-Griffiths, Zipeng Hu

Faraday rotation measures (RMs) are one of our few observational tools for measuring magnetic field strengths in extragalactic systems, but converting an RM to a magnetic field estimate requires knowledge of the electron column density -- the dispersion measure (DM) -- to the RM source. Because DMs are difficult to measure for most extragalactic radio galaxies, observers have adopted a range of strategies to estimate them from more easily measured quantities, but the accuracy of these approaches…

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astro-ph.SR

On the numerical reliability of nonadiabatic pulsation solutions in AGB envelopes

Jan Zalewski

We re-examine integration methods of linear nonadiabatic radial pulsations in the envelopes of AGB and post-AGB stars using the subspace shooting formulation. In the article the accuracy of the direct integration, the Riccati based method and a continuous renormalization nonlinear integration method are examined. The last method is not widely used in stellar pulsation studies and is therefore of interest in the present comparison. A tracking transformation of the two independent solution vectors…

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astro-ph.HE

Relativistic Oblique Shocks at Finite Temperature: Detachment Angle, Shock Polars, and the Turning Parameter

Rushikesh Ashok Sonkusale, Anshuman Verma, Ritam Mallick

Oblique shocks are ubiquitous in high-energy astrophysical environments, yet a systematic analytical treatment of how finite upstream temperature influences the maximum deflection angle has been lacking. We address this problem by developing a unified thermodynamic framework based on a novel dimensionless quantity, the turning parameter, which encapsulates the equation of state, upstream Mach number, and thermal state of the flow into a single variable. Starting from the relativistic Rankine-Hug…

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hep-phastro-ph.HEhep-ex

Charged Higgs Search at Future Neutrino Telescope and Higgs Factory

YiCheng Dai, Wei Liao, Yi-Song Lu, Qi-Shu Yan

We investigate the discovery potential of the charged Higgs boson at future lepton colliders and neutrino telescopes within two simplified benchmark scenarios with universal Yukawa couplings. We demonstrate that both the muon-track and cascade events at neutrino telescopes can be exploited to search for or constrain the charged Higgs boson through resonant neutrino scattering process, and we compare the sensitivities obtained under different astrophysical neutrino flux models. We study the effec…

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gr-qcastro-ph.HE

Using horizon shadows to distinguish a black hole and a white hole

Chengyu Bi, Zhoujian Cao

Within theoretical frameworks such as loop quantum gravity, black holes may evolve into white holes through a quantum bounce. This paper uses general relativistic ray-tracing techniques to calculate the ray-traced imaging of accretion disks from the previous cosmic stage during the Kerr black hole and post-bounce Kerr white hole phases. Calculations show that the black hole image presents a crescent emission ring and a central shadow. In contrast, after radiation from the previous universe penet…

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astro-ph.GA

Observations of High Galactic Latitude Line and Continuum Emission (912 - 1600 Å) with New Horizons

Jayant Murthy, James Overduin, Seth Redfield, J. Michael Shull, Joel Wm. Parker, Jon P. Pineau, Anne J. Verbiscer, Richard C. Henry et al.

We present observations of the cosmic ultraviolet background (CUVB) from 912 - 1600 A using the Stem aperture of the Alice spectrograph on the New Horizons spacecraft at 56 AU from the Sun, providing a spectral resolution of 9 A for diffuse sources. We detect emission lines of CIII (977 A) and CIV (1548/1551 A) at the 3 sigma level with strengths of 4200 +/- 1500 and 4100 +/- 1200 ph cm(-2) s(-1) sr(-1), respectively, and a marginal detection of OVI (1032/1038 A) at 1400 +/- 1300 ph cm(-2) s(-1)…

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astro-ph.HEgr-qchep-th

Exploring Physics beyond the Standard Model from kHz-Gravitational-Wave Signals of Core-Collapse Supernovae

Kei Kotake, Takami Kuroda

Recent advances in multidimensional modeling of core-collapse supernovae (CCSNe) have enabled detailed predictions of high-frequency gravitational-wave (GW) signals, offering a new probe of extreme matter and gravity. A proto-neutron star (PNS) emits quasi-continuous GWs through the excitation of its characteristic oscillation modes. State-of-the-art CCSN simulations show that these oscillations, in particular $g$- and $f$-modes, dominate the GW spectrum, with frequencies rising from a few hundr…

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astro-ph.COastro-ph.GAhep-ph

A lower bound on primordial power spectrum from halo substructure

Shin'ichiro Ando, Nagisa Hiroshima, Koji Ishiwata, Tomo Takahashi

We investigate how the primordial curvature perturbation of a certain wavelength scale affects the halo and subhalo structure. Primordial power spectrum considered in this paper features a nearly scale-invariant form with a cutoff at the wavenumber $ k = \mathcal{O}(1)~$Mpc$^{-1}$ and an additional log-normal bump at smaller scales. We compute the host halo evolution, as well as the subhalo mass function. To be consistent with the observations of stellar streams and gravitational lensing data, t…

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astro-ph.IMphysics.soc-ph

How to Craft the Right Language AI Policy For Your Research Group (Some Assembly Required)

Michelle Ntampaka, S. Burke-Spolaor, Ioana Ciucă, Ana Maria Delgado, Kartheik G. Iyer, Kelly Lockhart, Adele Plunkett, Mercedes López-Morales et al.

Language AI is rapidly becoming part of the astronomy research ecosystem, prompting research teams to develop policies governing its use. But resources and advice for AI adoption assume that all research groups share the same goals and values. This paper lays out an argument for why there is no single "correct" AI policy for astronomy research groups. Instead, we introduce four research laboratory archetypes with competing research priorities, and we use them to explore how a small laboratory or…

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physics.ins-detastro-ph.IMgr-qchep-ex

SQUID Readout of a High-$Q$ Superconducting $LC$ Resonator

Roman Kolevatov, Saptarshi Chaudhuri, Lyman Page

We demonstrate the readout of a superconducting $LC$ resonator, with $Q \approx 2 \times 10^{6}$ at approximately 250 kHz, using a dc SQUID followed by a SQUID series-array amplifier readout chain. We find that $Q$ depends on the SQUID flux-bias point, increasing near the shallow-slope point of the SQUID modulation curve and decreasing near the steep-slope point, consistent with the previously observed SQUID damping effects. From this variation, we infer the SQUID effective input impedance. We f…

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astro-ph.COastro-ph.GA

A Multimodal Approach to Star--Galaxy Separation using SPHEREx Spectrophotometry and DESI Legacy Survey Imaging

Kendrick Nguyen, Richard M. Feder, Sean Bruton, Uroš Seljak

Stellar contamination is a critical systematic for increasingly precise large-scale structure analyses from ongoing and next-generation surveys. Experiments targeting constraints on local primordial non-Gaussianity with $σ(f_{\rm NL}^{\rm loc}) \sim \mathcal{O}(1)$ demand sub-percent stellar contamination rates to avoid misidentifying spurious large-scale power induced by Galactic structure as true cosmological signal. In this work, we explore the use of multimodal models for star--galaxy separa…

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astro-ph.IM

The High-Energy Light Isotope eXperiment (HELIX) Instrument

P. S. Allison, M. Baiocchi, J. J. Beatty, L. Beaufore, D. H. Calderon, Y. Chen, S. Coutu, E. Ellingwood et al.

The HELIX detector is a balloon-borne instrument designed to measure the flux of light (Z < 11) cosmic-ray isotopes. In this paper we describe the initial configuration of HELIX, optimized for measurements in the energy range from approximately 0.2 GeV per nucleon to beyond 3 GeV per nucleon. In addition to a spectrometer, which is based on a one-tesla superconducting magnet and a drift-chamber tracker, HELIX employs scintillator-based time-of-flight counters and a ring-imaging Cherenkov detecto…

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astro-ph.SRastro-ph.EP

The Effects of Magnetic Accretion on the Spatial Extent of White Dwarf Pollution

Dang Pham, Aster G. Taylor, Tim Cunningham

Many white dwarfs are polluted by metals, which are generally understood to be the accreted remnants of a planetary system. Modeling these systems typically assumes that the metal concentration is homogeneous throughout the white dwarf's atmosphere. However, the magnetic fields of a white dwarf may affect the accretion geometry of the white dwarf via magnetospheric accretion. Convection in the white dwarf's photosphere will then transport the metals across the surface, with a structure set by th…

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astro-ph.SR

An extensive grid of DARWIN models for M-type AGB stars II. Effects of pulsation periods on wind properties

Emelie Siderud, Kjell Eriksson, Susanne Höfner, Arief Ahmad

Mass loss from asymptotic giant branch (AGB) stars is the result of a complex interplay between pulsation, atmospheric dynamics, dust formation, and radiative acceleration. Pulsation periods are a key input in dynamical atmosphere and wind models, and different prescriptions for assigning periods based on stellar parameters may lead to systematic differences in the predicted wind properties. To better constrain this critical parameter, we investigated how the choice of pulsation period affects t…

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astro-ph.GA

Hierarchical Bayesian inference with compositional score modeling for stellar streams

Giuseppe Viterbo, Jonas Arruda, Tobias Buck

Context: Stellar streams trace the gravitational potential of the Milky Way over a wide range of Galactocentric radii. Since different streams sample different regions of the Galaxy, combining several of them can constrain the global mass distribution more tightly than modeling any single stream in isolation. Most of the existing multi-stream analyses rely on likelihood-based methods that require a new inference run whenever additional streams or kinematic measurements become available. Aims: We…

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astro-ph.IM

RAMSES-GPU: Cell-by-Cell Adaptive Mesh Refinement with Magneto-Hydrodynamics and Self-Gravity on Graphics Processing Units

Romain Teyssier, Eric Moseley, Robert V. Caddy, Troels Haugbolle, James Sunseri, Jun-Young Lee, Jonathan Palafoutas, Yue Pan et al.

We present the implementation and optimization of the cosmological simulation code RAMSES on Graphics Processing Units (GPUs) using CUDA Fortran. This accelerated version ports the main computational routines, including hydrodynamics, particle dynamics, and self-gravity, to multi-GPU architectures. We detail our strategy for managing cell-by-cell Adaptive Mesh Refinement (AMR) on the GPU, utilizing bucket sort with prefix sums for AMR level sorting, radix sort via the CUB library for Hilbert key…

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astro-ph.HEnucl-th

Reaction-constrained composition \(g\)-modes in neutron stars with antikaon condensates, hyperons, and \(Δ(1232)\) resonances

Prashant Thakur, Ishfaq Ahmad Rather

We study core composition \(g_1\) modes of cold, nonrotating neutron stars containing antikaon condensates, hyperons, and \(Δ(1232)\) baryons and present, to our knowledge, the first calculation in full general relativity of the continuous-composition \(g_1\)-mode frequency and gravitational-wave damping time for stars with a \(K^-\) condensate. Using the BigApple relativistic mean-field equation of state, we compute frequencies, damping times, and frozen-composition tidal overlaps, and identify…

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astro-ph.SRastro-ph.EPastro-ph.GA

Statistics on the population of distant substellar companions to nearby stars

Souleymane Ouedraogo, Étienne Artigau, Sié Zacharie Kam, Orlagh L. Creevey, Clémence Fontanive, Neil J. Cook, René Doyon, Fabrice Bado et al.

Context. Wide substellar companions provide important benchmarks for studying the formation and evolution of brown dwarfs and giant planets. Their association with stellar primaries also provides age and metallicity constraints that are difficult to obtain for isolated objects. Aims. We investigate the population of wide substellar companions to nearby main-sequence stars using proper motions derived from multi-epoch WISE imaging. Our sample includes 2103 stars within 20 pc and is sensitive to c…

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astro-ph.IMastro-ph.GAastro-ph.HE

A multi-band radio flux density catalog of ICRF3 sources using the Onsala Twin Telescopes

Alva Kinman, Rüdiger Haas, Karine Le Bail, Jun Yang, Eskil Varenius

The VLBI Global Observing System (VGOS) is the next generation system for geodetic and astrometric Very Long Baseline Interferometry (VLBI). To optimize the observing time for each source in geodetic schedules, a flux density catalog is needed for the sources that are observed at the VGOS frequencies. The aim of this work is to monitor the flux densities of geodetic sources in the VGOS bands. The obtained flux density time series can be used for more effective scheduling of geodetic and astromet…

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gr-qcastro-ph.HEastro-ph.IM

A product template bank to search for compact binary coalescences microlensed by isolated point mass lenses

Sudhir Gholap, Sanjeev V. Dhurandhar, Shasvath J. Kapadia

Gravitational waves (GW) from stellar mass compact binary coalescences (CBCs) that encounter a lens whose Schwarzschild radius is comparable to the GW wavelength, will be microlensed, leading to frequency-dependent modulations in the observed signal. Neglecting such wave-optics effects in standard templated searches for CBCs can result in signal-to-noise ratio (SNR) losses as large as 30%. Here, we present a prescription for constructing a template bank targeted at microlensed GWs. We consider C…

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astro-ph.COastro-ph.GA

When galaxies burst II. Implications of enhanced burstiness for the 21-cm Cosmic Dawn signal

Hovav Lazare, Sarah Libanore, Eleonora Vanzan, Julian B. Muñoz, Ely D. Kovetz

Recent JWST observations suggest that star formation in the early universe was substantially burstier than assumed in standard models. Such burstiness can be described as a stochastic process characterized by the burst amplitude and the coherence time of star formation epochs. In this paper, we investigate how bursty star formation modifies the 21-cm power spectrum during Cosmic Dawn through its impact on the non-local radiation fields that govern its evolution, namely Lyman-$α$ and X-ray backgr…

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astro-ph.SRastro-ph.EP

A Quiet Host in an Active Planet-Forming Disk: Optical Spectroscopy of WISPIT

C. Swastik, M. Bestha, L. S. Sonith, S. Facchini, T. Sivarani, R. K. Banyal, Z. Wahhaj, A. Choudhary et al.

WISPIT 2 is a young pre-main-sequence star hosting a multi-ringed transition disk and two directly imaged protoplanets, including the accreting WISPIT 2b, making it the closest known analogue to PDS 70. We present the first optical spectrum of its central star, obtained with HFOSC on the 2-m Himalayan Chandra Telescope, and derive its atmospheric parameters, test its youth, and constrain its accretion state. We analyse low-resolution spectra with iSpec and validate the pipeline at HFOSC resoluti…

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astro-ph.SRastro-ph.EP

A Quiet Host in an Active Planet-Forming Disk: Optical Spectroscopy of WISPIT 2

C. Swastik, M. Bestha, L. S. Sonith, S. Facchini, T. Sivarani, R. K. Banyal, Z. Wahhaj, A. Choudhary et al.

WISPIT 2 is a young pre-main-sequence star hosting a multi-ringed transition disk and two directly imaged protoplanets, including the accreting WISPIT 2b, making it the closest known analogue to PDS 70. We present the first optical spectrum of its central star, obtained with HFOSC on the 2-m Himalayan Chandra Telescope, and derive its atmospheric parameters, test its youth, and constrain its accretion state. We analyse low-resolution spectra with iSpec and validate the pipeline at HFOSC resoluti…

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astro-ph.EPastro-ph.SR

Evidence for a giant companion orbiting Tabby's star

Cristina Madurga-Favieres, P. A. Strøm, Thomas G. Wilson, Neda Heidari, Flavien Kiefer

KIC 8462852, also known as Tabby's star, shows deep, irregular flux variations up to 20 per cent in its Kepler light curve. These unusual events show no apparent periodicity. Multi-wavelength observations show the dips are consistent with transiting dust, although its origin remains uncertain. The leading explanation is that dust may originate from a family of exocomets or planetesimal fragments. TESS data reveal a unique, symmetric transit event consistent with a planet or brown dwarf. This wou…

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