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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GA

Triaxiality of the Milky Way dark matter halo and the microlensing optical depth towards the Large Magellanic Cloud

J. García-Bellido, M. R. S. Hawkins

The microlensing optical depth towards the Large Magellanic Cloud (LMC), $τ_{\rm LMC}$, bounds the compact-object fraction of the Galactic dark matter halo, but is almost always evaluated for a spherical halo. We compute it for triaxial haloes and show that the shape dependence is carried entirely by the projection of the line of sight onto the halo principal axes: for a scale-free halo $ρ\propto R^{-α}$ at fixed local density it factorises exactly as $τ/τ_{\rm sph}=S_\odot^α\langle S^{-α}\rangl…

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astro-ph.EP

TEMPUS: Relativistic coordinate time scales for any solar-system body from arbitrary ephemerides

Yan Seyffert, Agnès Fienga

Precise time-scale transformations between solar-system bodies are an essential requirement for deep-space science and solar system navigation. The post-Newtonian relativistic expression relating a body-centered coordinate time TCX to the Barycentric Coordinate Time TCB depends on the gravitational environment and velocity of the target body, and must be evaluated consistently with the chosen planetary ephemerides. So far only INPOP has provided such a solution as part of its ephemerides release…

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astro-ph.EP

TEMPUS: Relativistic coordinate time scales for any solar-system body from arbitrary ephemerides

Yan Seyffert, Agnès Fienga

Precise time-scale transformations between solar-system bodies are an essential requirement for deep-space science and solar system navigation. The post-Newtonian relativistic expression relating a body-centered coordinate time TCX to the Barycentric Coordinate Time TCB depends on the gravitational environment and velocity of the target body, and must be evaluated consistently with the chosen planetary ephemerides. So far only INPOP has provided such a solution as part of its ephemerides release…

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astro-ph.GA

Euclid: Quick Data Release (Q1) -- Exploring the detailed visual morphology of galaxies in clusters

P. Mas-Buitrago, S. Kruk, D. O'Ryan, M. T. Nardone, A. La Marca, P. Awad, M. Baes, M. Fossati et al.

Galaxy clusters provide unique laboratories for studying environmental effects on galaxy evolution. The morphology--density ($T$--$Σ$) and morphology--cluster-centric radius ($T$--$R$) relations trace how galaxy morphology is influenced by the environment, but previous studies at intermediate redshifts have been limited in both sample size and radial coverage. We use the Euclid Quick Data Release 1 (Q1) visual morphology catalogue to measure the $T$--$Σ$ and $T$--$R$ relations for smooth, featur…

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astro-ph.EP

Interplanetary Dust Ablation Seeds Silicate Clouds in Exoplanet Atmospheres

Sven Kiefer, Gregory J. Gosselin, Caroline V. Morley, Sean P. S. Gulick

Interplanetary dust particles (IDPs) are present throughout the Solar System, with Earth experiencing a mass flux of roughly 100 tonnes of IDPs per day. These particles ablate in the upper atmosphere, delivering aerosols that form noctilucent and stratospheric clouds. Since IDPs are present in exoplanet systems as exozodiacal dust disks (exozodis), it is likely that exoplanets experience a constant infall of IDPs as well. In this work, we investigate the effect of IDPs on the cloud structure of…

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astro-ph.SRastro-ph.GA

An analysis of four stellar rings

E. Paunzen, J. Florian, A. Gütl-Wallner, A. Herdin, E. Kralofsky, K. Leschinski, M. Mach, H. M. Maitzen et al.

About 50 years ago, one thousand ring-like structures (called stellar-rings) were discovered by Isserstedt (1968). They were believed to be groups of young stars formed by shell-like triggered star formation, which would make them excellent tracers of spiral arms, for example. Neglected for 40 years, we used highly accurate kinematic, astrometric, and photometric data to investigate the four most prominent stellar rings. The aim is to investigate if those structures are indeed physically related…

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astro-ph.SR

Now you see me, now you don't: Deep, long-lived obscuration events of white dwarfs by dust and debris from disintegrating planetesimals

J. van Roestel, S. Bhattacharjee, J. A. Guidry, I. Caiazzo, T. Cunningham, J. J. Hermes, S. Torres, Z. Vanderbosch et al.

Transiting dust and debris around white dwarfs provide a direct view of planetary disruption. We report six previously non-variable white dwarfs that underwent single, deep obscuration events, including ZTF~J2327+0019, which fully disappeared for more than a year. These discoveries raise the number of confirmed debris-transit white dwarfs to 20. In addition, the systematic search of negative alerts from the Zwicky Transient Facility (ZTF), followed by photometric and spectroscopic observations,…

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astro-ph.HE

Resolving structure within the iron line profile of Serpens X-1 with XRISM and NuSTAR

Hayden Hall, Renee M. Ludlam, Edward Cackett, Jon M. Miller, Javier A. García

We present the first simultaneous XRISM and NuSTAR observations of the neutron star low mass X-ray binary Serpens X-1. We perform spectral modeling on the joint observations of XRISM/Resolve, XRISM/Xtend, and NuSTAR, testing Comptonization and double thermal continuum model prescriptions. We find that a hybrid double thermal model adequately describes the underlying continuum of the source while the Comptonization models predict largely unphysical parameter values. We perform reflection modeling…

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astro-ph.HE

Strong Polarization Signatures from Magnetically Stabilized Luminous Thin Accretion Disks

P. Chris Fragile, Peter Anninos, Madeline Breiling, Derrick Pickrel, Gabrielle Ruminski

We utilize the Monte Carlo radiation transport capabilities of Cosmos++ to explore the polarization and Faraday rotation of radiation emitted from a set of general relativistic radiation magnetohydrodynamic simulations of magnetically stabilized, thin, black hole accretion disks. The guiding question is whether or not the Faraday rotation depolarizes the radiation to such a degree as to be inconsistent with the relatively high polarization measurements coming from the Imaging X-ray Polarimetry E…

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astro-ph.GA

Turbulence Cascade in Cygnus X Revealed by Multi-point VDF Method

Junjie Huang, Yangjun Pu, Keping Qiu, Junhao Liu, Yingxi Li, Mengke Zhao

Turbulence plays a crucial role in regulating star formation activities within molecular clouds, yet few methods can directly reveal its properties and underlying processes. We use molecular line data from the Nobeyama 45m Cygnus X CO Survey to study the turbulence properties and their relationships with star-forming activities and/or other non-thermal motions. In this work, we apply the multi-point velocity dispersion function (VDF), rather than direct linewidth measurements, to investigate the…

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nucl-thastro-ph.HEhep-ph

How strange: Phase diagrams with 3 critical points

Mateus Reinke Pelicer, Nikolas Cruz Camacho, Rajesh Kumar, Veronica Dexheimer, Jacquelyn Noronha-Hostler

We show that the Chiral Mean-Field model (CMF) can produce a phase diagram with three critical points: the nuclear liquid-gas transition, quark deconfinement, and a strangeness driven transition. The strangeness driven transition separates a mainly nucleonic phase from one dominated by hyperons and baryon resonances. We discuss the compositional change in these transitions and their possible signatures in heavy-ion collisions and neutron star mergers.

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astro-ph.SR

The role of specific entropy in the onset of the luminosity bump

S. Hekker

During their evolution, stars follow a distinct path in luminosity--temperature space. Low-mass stars that have exhausted hydrogen in their core follow the so-called red-giant branch which is predominantly in the direction of increasing luminosity and decreasing surface temperature. The luminosity bump is a temporary decrease in luminosity against this otherwise increasing trend. The bump is present in both observations and stellar evolution models. However, with canonical physics included in th…

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hep-phastro-ph.HE

Axion Hair and Pulsar Electrodynamics: modelling, discharge dynamics, and particle-in-cell simulations

Samuel J. Witte, Andrea Caputo, Stefan Stelzl, Alexander Chernoglazov, Alexander A. Philippov, Surjeet Rajendran

In a companion paper, we demonstrated that static axion field gradients sourced by dense nuclear matter (\emph{axion hair}) can dominate the near-field electrodynamics of old rotation-powered pulsars, leading to new constraints on light QCD axions and on CP-violating axion-nucleon interactions. This article provides the extended theoretical and numerical framework underlying those results. We begin by providing a detailed description of the sourcing of axion hair from dense nuclear matter, compu…

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astro-ph.COastro-ph.GA

Why Azimuthal Averaging Works in Halo Lensing: Symmetry and Power Counting for Nonlinear Shear and Magnification

Keiichi Umetsu

Cluster weak-lensing analyses often compress two-dimensional lensing fields into azimuthally averaged radial profiles and evaluate nonlinear observables from the averaged convergence and shear. However, the ring average of a nonlinear observable generally differs from the mean-field prediction formed from the averaged fields. This difference, divided by the mean-field prediction, defines the fractional residual. For a complete ring, the difference begins at second order in angular fluctuations.…

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astro-ph.HE

Phase-Resolved Ultra-High-Energy Emission Defines an Energetic Boundary for Compact-Object Engines and Dense-Matter Structure

Marlon M. S. Mendes, Cesar H. Lenzi

We show that phase-resolved ultra-high-energy emission from LS I +61 303 defines a critical energetic boundary linking the compact-object engine, circumstellar interaction depth, and dense-matter structure. Combining the GeV-TeV-UHE spectral transition with an orbital acceleration-transparency sieve and branch-resolved stellar sequences for 116 certified EoS, we find that the measured 25-100 TeV tail primarily constrains the circumstellar environment, whereas a more demanding pure-hadronic > 1 T…

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astro-ph.GA

Virgo Filaments VII: MeerKAT HI-imaging of the VirgoIII filament

M. Ramatsoku, G. Nagaraj, P. Jablonka, R. A. Finn, B. Vulcani, G. Rudnick, F. Combes, G. De Lucia et al.

We present MeerKAT HI observations of galaxies in the nearby Virgo III filament. At a median distance of $\sim30$ Mpc, the filament extends over $\approx16$ Mpc across $\sim56$ deg$^2$. Our survey comprises 15 targeted MeerKAT pointings centred on HI deficient galaxies. Multi-resolution HI imaging at 8-90 arcsec with an rms of $\sim0.3$ mJy beam$^{-1}$ reaches column densities of $\sim4\times10^{20}$ to $\sim4\times10^{18}$ atoms cm$^{-2}$. This probes HI in galaxy discs at $\sim1.2$ kpc resolut…

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astro-ph.HEastro-ph.IMgr-qc

Enabling new sampling strategies for continuous-wave analyses by integrating Bilby into PyFstat

Maria-Antonia Ferrer-Martinez, David Keitel

Continuous-wave searches for rotating neutron stars usually cover wide parameter spaces and produce a large number of candidate signals. Stochastic sampling methods therefore play an important role in candidate follow-up and parameter estimation. We present the integration of the Bayesian inference library BILBY into the open-source continuous-wave analysis package PyFstat, enabling access to the broad range of stochastic samplers available through BILBY while preserving the existing PyFstat ana…

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astro-ph.HEastro-ph.IMgr-qc

Enabling new sampling strategies for continuous-wave analyses by integrating Bilby into PyFstat

Maria-Antonia Ferrer-Martinez, David Keitel

Continuous-wave searches for rotating neutron stars usually cover wide parameter spaces and produce a large number of candidate signals. Stochastic sampling methods therefore play an important role in candidate follow-up and parameter estimation. We present the integration of the Bayesian inference library BILBY into the open-source continuous-wave analysis package PyFstat, enabling access to the broad range of stochastic samplers available through BILBY while preserving the existing PyFstat ana…

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astro-ph.HEastro-ph.GA

Compton-induced HE -- VHE $γ$-rays from pair cascade emissions in the SEDs of radio galaxies: NGC 1275

Mfuphi Ntshatsha, Markus Böttcher, Soebur Razzaque

In the scheme of active galactic nuclei (AGNi), the blazar subclass is particularly bright in $γ$-rays. This is because of their emissions being beamed into our line of sight, as opposed to their misaligned parent population, radio galaxies. This work presents results of a Monte-Carlo code that propagates jet-collimated $γ$-rays through the magnetized AGN environment, leading to secondary cascade emissions from relativistic electron-positron pairs. The resulting multi-wavelength emissions are us…

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astro-ph.GA

Design and commissioning of a windowless gas-target system for high-current beams at JUNA

Xuyang Wanga, Fuqiang Cao, Weike Nana, Gang Lian, Wei Nan, Hongwei Huang, Yuchen Jiang, Jingyu Dong et al.

Windowless gas targets avoid the beam-energy loss and straggling introduced by entrance foils and are therefore well suited for direct measurements of low-energy nuclear reactions. A windowless gas-target system designed for operation with milliampere beams has been developed for the Jinping Underground Nuclear Astrophysics facility (JUNA). The system combines three-stage differential pumping, closed-loop gas recovery and purification, a constant-temperature power-compensation calorimeter, and a…

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astro-ph.GA

Design and commissioning of a windowless gas-target system for high-current beams at JUNA

Xuyang Wang, Fuqiang Cao, Weike Nan, Gang Lian, Wei Nan, Hongwei Huang, Yuchen Jiang, Jingyu Dong et al.

Windowless gas targets avoid the beam-energy loss and straggling introduced by entrance foils and are therefore well suited for direct measurements of low-energy nuclear reactions. A windowless gas-target system designed for operation with milliampere beams has been developed for the Jinping Underground Nuclear Astrophysics facility (JUNA). The system combines three-stage differential pumping, closed-loop gas recovery and purification, a constant-temperature power-compensation calorimeter, and a…

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astro-ph.GAastro-ph.CO

Weak cool core, weak turbulence: XRISM, XMM-Newton and Chandra spectroscopy of the core of Abell 1413

Egemen Gormez, Murat Hudaverdi

We present the first XRISM spectroscopy of the core of Abell 1413 (z = 0.143), combining 104.7 ks of Resolve with archival XMM-Newton and Chandra spectra of a matched sky region. A1413 is hot, massive and relaxed but lacks a strong cool core (t_cool = 6.4 Gyr), a regime in which the low turbulence reported to date has been tested only once, in A3571. The Resolve spectrum requires a single velocity-broadened component with kT = 7.06 (+0.33, -0.43) keV and a line-of-sight velocity dispersion sigma…

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astro-ph.GAastro-ph.CO

Detection prospects for heavy WIMP dark matter around M31* in microwave band

Andrei E. Egorov

This work analyzes the detection prospects for weakly interacting massive particles (WIMPs) in dark matter (DM) density spike around the supermassive black hole (SMBH) in Andromeda galaxy M31 in microwave band. WIMP annihilation produces relativistic electrons and positrons, which generate the synchrotron emission in strong magnetic field of the accretion flow medium at microwave frequencies. Properties of this emission, as well as their dependence on DM and medium parameters, were modeled. Atac…

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astro-ph.HEhep-phnucl-th

A Two-Parameter Framework for the Diffuse Supernova Neutrino Background

Cecilia Lunardini, Xingyun Yang

Following important experimental developments, tests of the Diffuse Supernova Neutrino Background (DSNB) are entering a new phase that might lead to a discovery. This motivates the development of simple and broadly applicable tools for comparing theoretical predictions and interpreting experimental results. We show that, over the energy range relevant to current detectors, the DSNB is well described by an exponential spectrum, characterized by the differential flux at 20 MeV, $φ_{20}$, and a spe…

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astro-ph.HE

A Unified Timescale Relation for Quasi-Periodic Eruptions and Repeated Nuclear Transients

Shifeng Huang, Tinggui Wang, Ning Jiang, Yibo Wang, Zhenfeng Sheng, Tian-Yu Xia, Jiazheng Zhu, Zheyu Lin et al.

Quasi-periodic eruptions (QPEs) and recurrent nuclear transients (RNTs) exhibit recurrent high-amplitude flares from galactic nuclei, yet their characteristic timescales remain poorly understood. In this work, we compile a sample of these systems and investigate empirical scaling relations between flare timescales and black hole masses. We find that the recurrence timescale exhibits a positive but highly scattered dependence on black hole mass in the combined QPE and RNT sample, approximately fo…

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astro-ph.HE

Stratified Wind Geometries of GRS 1915+105: Density Profiles and Radii

Noa Keshet, Ehud Behar, Jon M. Miller, Joey Neilsen

The low-mass X-ray binary GRS 1915+105 exhibits dramatic spectral and flux variability, often accompanied by highly ionized outflows. In this work, we analyze four archival Chandra/HETG observations spanning over a decade, which vary greatly in their ionizing spectrum from soft (low inner disk temperature) to hard (high inner disk temperature). We measure the wind properties, using the insightful tool of the absorption measure distribution (AMD, a distribution of column density with ionization).…

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astro-ph.EP

Centaur Longevity Revisited: Reclassification of the Bailey and Malhotra Sample with Modern Orbital Solutions and Astrometric Constraints

Naresh Prasannaa, Chrisphin Karthick

Bailey & Malhotra (2009; BM09) assigned dynamical classes to individual Centaurs using 2007 Minor Planet Center orbital elements. They classified 2005 TH173 as quasi-stable (Q) from a 17-day observational arc. We revisit this scheme using modern JPL Small-Body Database elements (2026-07-26), REBOUND WHFast integrations, and diagonal clone ensembles to separate orbital uncertainty from intrinsic chaotic divergence in dynamical lifetimes. For Centaurs with observational arcs >=30 d, the within-obj…

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astro-ph.HEastro-ph.IM

Supermassive black hole binaries in the multi-messenger context of ground and spaceborne VLBI

B. Hudson, L. I. Gurvits, D. J. D'Orazio, C. Tiede, T. M. Eubanks, E. Mooij

Evidence of a gravitational wave background suggests the existence of a population of sub-parsec supermassive black hole binaries (SMBHBs), with characteristic angular separations on the order of 1-10 $μ$as. Spaceborne extensions of Very Long Baseline Interferometry (VLBI) and the next generation ground arrays introduce the possibility of directly imaging these SMBHBs. In this work, a binary Spectral Energy Distribution (SED) model is used to predict the detectability of SMBHBs with ground and s…

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astro-ph.IMeess.SPmath-phphysics.comp-phphysics.ins-det

Full Characterisation of the Polarisation Primary Beam of the GRAO 32-m Telescope

Theophilus Ansah-Narh, Nia Imara, Benedicta Woode, Joseph Bremang Tandoh, Emmanuel Proven Adzri, Diana Klutse, Evaristus Uzochukwu Iyida

Direction-dependent instrumental polarisation is a major systematic limitation in high-fidelity single-dish radio polarimetry, yet a unified characterisation of beam leakage and the conditioning of polarisation recovery is lacking for the Ghana Radio Astronomy Observatory (GRAO) 32-m telescope. We aim to establish a quantitative, direction-dependent polarimetric beam model at 5.0 and 6.7 GHz. High-resolution \texttt{GRASP} electromagnetic simulations of the nominal telescope configuration are us…

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astro-ph.IMgr-qc

A Content-Addressed Workflow for Reproducible DANTE Gravitational-Wave Anomaly Analysis

Luca Cirfeta

Unsupervised analysis of gravitational-wave detector data combines expensive scientific stages with data acquisition, provenance checks, statistical calibration, follow-up products, and reporting. Reproducing such an analysis requires more than preserving model weights or a final candidate table: the execution graph, scientific contracts, retry semantics, and verification boundary must also be explicit. We present a local workflow layer for the Domain-Adaptive Network for Transient Evaluation (D…

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