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Research Trends

Latest preprints in space engineering and astrophysics.

physics.opticsastro-ph.IM

Laser Remelting for Reduced Porosity on Additively Manufactured Aluminium Mirrors

Joshua West, Valentina Oyarzun, Marcell Westsik, Younes Chahid, Magdalena Kraus, Scott McPhee, William Brzozowski, Samuel Tammas-Williams et al.

Additively manufactured (AM) AlSi10Mg mirrors are fabricated through laser powder bed fusion (LPBF), allowing the use of complex geometries such as lattices and organic structures that enable high mass reduction while maintaining mechanical stiffness. Micron-sized pores that cause optical scatter may form during LPBF as a consequence of deviations from the optimal processing window, particularly from laser energy input and scan strategy. This work proposes a laser remelting strategy aimed at red…

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astro-ph.COastro-ph.GA

Contribution to the 2026 Cosmology session of the 60th Rencontres de Moriond: Galactic moments: Understanding polarized foregrounds complexity in the quest for CMB primordial $B$ modes with LiteBIRD

S. Vinzl, J. Aumont, L. Vacher, R. T. Génova-Santos, D. Adak, A. Rizzieri, for the LiteBIRD Collaboration

Accurate modeling of polarized Galactic emission has become a major challenge for current and next-generation cosmic microwave background (CMB) $B$-mode experiments. Ignoring the spectral complexity of thermal dust and Galactic synchrotron emission when integrating along the line of sight and over large sky fractions inevitably leads to biases in CMB polarization analyses. In this work, we review how the future LiteBIRD satellite, which will benefit from an increased number of bands and sensitiv…

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physics.atom-phastro-ph.SRphysics.plasm-ph

Plasma screening and configuration interaction effects induced large enhancement on L-shell photoionization cross sections and opacity

Fuyang Zhou, Shengbo Niu, Simei Lu, Chuangying Li, Xiang Gao, Yong Wu, Yizhi Qu, Jianguo Wang et al.

An opacity model that incorporates improved treatments of both plasma screening and configuration interaction (CI) effects is proposed, and a 25-30% enhancement on the iron L-shell opacity is predicted at solar interior temperatures. It is originated from the plasma screening induced 14-17% enhancement on the photoionization cross sections and the CI induced 10-20% enhancement on photoexcitation and photoionization cross sections for open L-shell ions. These explain the long-standing discrepancy…

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astro-ph.GA

High-Resolution [CI] $({^3\mathrm{P}_2}\rightarrow{^3\mathrm{P}_1})$ and CO $(J=7\rightarrow6)$ Observations of Circumnuclear Disks in Nearby Seyfert Galaxies

Dragan Salak, Suphakorn Suphapolthaworn, Yusuke Miyamoto, Naomasa Nakai, Masumichi Seta, Kazuo Sorai

We present [CI] $({^3\mathrm{P}_2}\mathrm{-}{^3\mathrm{P}_1})$, CO $(J=7\mathrm{-}6)$, and 800-GHz continuum observations of the circumnuclear disks (CNDs) in the Seyfert galaxies NGC 613 and NGC 1808 with the Atacama Large Millimeter/submillimeter Array. The images reveal the distributions of neutral gas and dust in nearby galaxy nuclei at a resolution of $0.2''$ (10 pc) which is unprecedented at these frequencies. Both lines and continuum exhibit peaks at the position of molecular tori. The ma…

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astro-ph.SR

Comparative 3D Asymmetric Expansion and Angular Widths Evolution of Fast and Slow Coronal Mass Ejections

Anjali Agarwal, Wageesh Mishra, Jie Zhang, Soumyaranjan Khuntia, Manuela Temmer

The radial and lateral dimensions of coronal mass ejections (CMEs) influence their duration and probability of encounter at Earth. These properties are linked to the expansion speed of CMEs in different radial and lateral directions; however, most earlier studies modeled CME evolution using a projected full ice-cream cone geometry, which does not distinguish between radial and lateral expansion. Our study investigates the asymmetric expansion (relative radial and lateral components) and kinemati…

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astro-ph.GAastro-ph.CO

The Stellar Mass Function of Gas-Rich Galaxies and the Underlying $M_{\rm HI}-M_{\rm star}$ Scaling Relation in the Local Universe

Tanya Tripty, Nishikanta Khandai, Saili Dutta, Khushi Sharma

We estimate the Galaxy Stellar Mass Function (GSMF) of HI gas-rich galaxies using the 100\% ALFALFA ($α$) catalog, $\sim 98\%$ of which have optical counterparts in the Sloan Digital Sky Survey (SDSS) and a subset of them have counterparts in GALEX SDSS WISE Legacy Catalogue-2(GSWLC-2). We use the mass estimates from this subset which combines UV, optical and IR bands with individual dust corrections to recalibrate optical stellar mass estimates. We use a non-parametric method to estimate the GS…

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hep-phastro-ph.HEastro-ph.SRhep-ex

MeV Electrophilic Axion-like Particles from Sun

Shao-Feng Ge, Sk Jeesun, Tao Li

This work explores the production of an MeV-scale electrophilic axion-like particles (ALPs) by utilizing the monochromatic 5.5MeV photon resulting from the nuclear fusion processes in the Sun. These 5.5MeV photons can undergo the Compton-like scattering with the ambient electrons in the solar matter to produce a substantial flux of MeV ALPs. Upon reaching the Earth, such ALPs can be detected via the same electron coupling, offering a new opportunity for the dark matter (DM) direct detection expe…

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astro-ph.IM

Infrasound Newtonian Noise Estimation at the Einstein Telescope Candidate Site Sos Enattos

Wathela Alhassan, D. Rosinska, M. Suchenek, E. Fenyvesi, T. Bulik

We investigate the seasonal variability of atmospheric infrasound and its contribution to Newtonian noise (NN) at the Sos Enattos site, a leading candidate location for the Einstein Telescope (ET). Infrasound data recorded at three stations -- SOE0 (surface), SOE1 ($-84$ m), and SOE3 ($-160$ m) -- are analyzed over multiple seasons to characterize both temporal variability and the depth dependence of the acoustic field. The amplitude spectral density (ASD) at 1 Hz exhibits a clear seasonal modul…

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astro-ph.GA

What's Missing in AGN Feedback? Lessons learnt from Magneticum, IllustrisTNG and Simba

D. T. Mazengo, P. Popesso, I. Marini, L. M. Valenzuela, N. de Isídio, V. Toptun, Mirjana Pović, Petri Väisänen et al.

Accurately balancing gas reservoirs, star formation, and feedback across cosmic time remains a central challenge for galaxy formation models in modern hydrodynamical simulations. While different feedback prescriptions reproduce selected local galaxy properties with varying success, the most pronounced discrepancies emerge in predictions for the hot gas content of dark matter halos. We examine three state-of-the-art cosmological simulations: Magneticum, IllustrisTNG, and SIMBA, which struggle to…

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astro-ph.IM

Fast Inference on Astronomical Time Series with Trans-Dimensional Flow Matching Posterior Estimation

Nina van der Meulen, Tin Hadži Veljković, Daniela Huppenkothen, Benjamin Kurt Miller, Christoph Weniger

The analysis of time series plays an important part in the study of (fast) transient events, including gamma-ray bursts, magnetar bursts, fast radio bursts, and solar flares. A common approach is to decompose the time series into pulses and study the pulse characteristics, such as location and amplitude, in order to constrain physical models of the source and its environment. However, estimating both the number and characteristics of these pulses presents a trans-dimensional inference problem th…

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astro-ph.GA

MIGHTEE: The Host-Galaxy Associated Catalogue of the Radio Sources in MIGHTEE Continuum Data Release 1

C. L. Hale, J. Hamlett, I. H. Whittam, M. J. Jarvis, M. J. Hardcastle, S. L. Jung, N. Stylianou, R. G. Varadaraj et al.

Radio continuum surveys provide samples of active galactic nuclei (AGN) and star forming galaxies (SFGs) to high redshifts, free of biases due to dust obscuration. However, radio detected sources require multi-wavelength counterparts to understand their intrinsic properties (e.g. redshift, stellar mass) and to study the evolution of star formation and AGN activity. In this work we present host galaxy counterparts for the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey…

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astro-ph.SR

Transport of angular momentum and chemical elements by the MRI dynamo in stellar radiative zones

Laurène Jouve, François Lignières, Jérôme Guilet, Alexis Vanbesien

The question of angular momentum transport by magnetic fields has recently been revived by the detection of magnetic fields in the deep interior of red giant stars. We aim at characterizing the efficiency of the transport of angular momentum and chemical elements in a stellar radiative zone subject to the magneto-rotational instability, in situations where hydrodynamical instabilities are not triggered. We use a large set of zero-net flux shearing-box simulations modelling a portion of a stellar…

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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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