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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.HEastro-ph.CO

Which Type Ia supernova observables best indicate the ages of their progenitor stars?

Young-Lo Kim, Chul Chung, Young-Wook Lee, Seunghyun Park, Junhyuk Son, Suk-Jin Yoon

Type Ia supernovae (SNe Ia) observables, such as the light-curve shape and the colour, are expected to contain information about the progenitor star. In this work, we explore this information, with a particular focus on the age of the SN Ia progenitor star. For this, we construct the SN Ia progenitor age distribution (SPAD) and compare it to the observed distributions of light-curve shape (x1) and the colour (c) parameters in a volume-limited SN Ia sample. We find that SPAD and the x1 distributi…

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astro-ph.HE

Long-term X-ray spectral analysis of Cygnus X-1 using AstroSat

H Lalthantluanga, Akash Garg, Ranjeev Misra, Vanzarmawii Chhangte, Lalthakimi Zadeng

We performed a spectral analysis of long-term observations (2016-2019) of the black hole binary Cygnus X-1 using AstroSat, covering its hard, intermediate, and soft states. During soft states, we found that a typical spectrum fitted with a single Comptonization, a thermal disc, and an iron line yields poor fits and unphysically small disk radii (R_in < 1 R_g). While adding a relativistic disk component (kerrbb) improved the fit but required high color factors (f_col ~ 3.35-5.08), indicating addi…

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astro-ph.GA

Unified modelling of broad and narrow optical-UV emission lines from massive black holes: interpreting high-redshift JWST observations

Adele Plat, Michaela Hirschmann, Emma Curtis-Lake, Anna Feltre, Stephane Charlot, Steven L. Finkelstein, Lorenzo Napolitano, Fabio Pacucci et al.

JWST is uncovering a large population of active galactic nuclei (AGN) at high redshift, motivating the extension of models calibrated on local sources to a broader range of physical conditions. We present a consistent suite of broad- and narrow-line photoionisation models based on ionising spectra that vary with black-hole mass and Eddington ratio, spanning sub- to super-Eddington accretion. For the broad-line region (BLR), we investigate the detectability of low-mass accreting black holes. At z…

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astro-ph.GAastro-ph.CO

BAQARO: Tracing Stochastic Black Hole Growth Histories and Quasar Lightcurves in a Cosmological Context

Elia Pizzati, Joseph F. Hennawi, Joop Schaye

How supermassive black holes (BHs) assemble their mass and power the luminous quasars we observe across cosmic time remain central open questions in galaxy evolution. We present BAQARO, a semi-empirical framework for BH growth. Built on subhalo merger trees extracted from the FLAMINGO-10k simulation, the model links BH growth histories to those of their host subhalos through prescriptions that capture both average trends and stochastic variability. BAQARO is constrained by the bolometric quasar…

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astro-ph.GA

Galaxies in the first two billion years: Earlier formation and quenching with surface-density modulated star formation and feedback

Akash Vani, Mohammadreza Ayromlou, Guinevere Kauffmann, Volker Springel

JWST has revealed massive, UV-bright, compact, and in some cases quenched galaxies in the first two billion years of cosmic history, challenging current galaxy formation models. We develop an extended L-Galaxies semi-analytic model, run on the MillenniumTNG dark-matter-only simulation, and follow galaxy evolution over $0 \le z \lesssim 15$. The model ties the star formation efficiency and the coupling of stellar feedback energy to the local cold gas surface density, making star formation efficie…

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astro-ph.GA

Resolved SED Modeling with JWST and ALMA: The Role of Stellar Mass Surface Density in Regulating Star Formation in Cosmic Noon Galaxies

Cheng-Lin Liao, Leindert A. Boogaard, Jacqueline A. Hodge, J. Li, E. da Cunha, P. Sharda, A. Battisti, C. Lagos et al.

We present kpc-scale ($0.2''-0.5''$) physical property maps of 35 main-sequence galaxies at $z \approx 0.5-3.7$, with stellar masses of $\log(M_*/M_\odot) \sim 9.7-11.7$ and star formation rates of $\mathrm{SFR} \sim 1.4-280\,\mathrm{M_\odot\,yr^{-1}}$, selected from the ALMA Spectroscopic Survey (ASPECS) in the Hubble Ultra Deep Field. Leveraging the unique HST, JWST (NIRCam and MIRI), and ALMA observations, we perform spatially resolved spectral energy distribution (SED) modeling across the UV…

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gr-qcastro-ph.HE

Accretion onto a moving black hole for stiff equations of state

Elliott Ewell, Peter K. Harris, Thomas W. Baumgarte, Stuart L. Shapiro

We revisit accretion of an asymptotically uniform fluid onto a moving Schwarzschild black hole, the relativistic analog of Bondi-Hoyle-Lyttleton accretion. Expanding on previous treatments, we focus on relativistic accretion of stiff fluids with adiabatic indices $Γ\geq 5/3$, which is particularly relevant for the treatment of primordial black holes captured by neutron stars. We perform numerical simulations to systematically explore the dependence of the steady-state accretion and drag rates on…

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astro-ph.HE

Time-Integrated Searches for Sub-TeV Neutrino Sources with IceCube-DeepCore

R. Abbasi, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, J. M. Alameddine, S. Ali, N. M. Amin et al.

We have developed techniques for a competitive sub-TeV time-integrated neutrino search and applied it to 11.1 years of IceCube-DeepCore data. The DeepCore subarray lowers the sensitivity of IceCube down to sub-TeV energies and is especially interesting for objects with soft spectra. Three studies were performed: a search for neutrino emission from AGN exhibiting high intrinsic X-ray flux, including NGC 1068, as identified by SWIFT/BAT; a search for neutrino emission from Galactic objects identif…

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astro-ph.COastro-ph.HE

Reconsidering the role of bright and dark gravitational-wave standard sirens for cosmology

Alberto Colombo, Sonia Triscari-Benimavò, Simone Mastrogiovanni

Gravitational-wave (GW) standard sirens have emerged as powerful probes of cosmic expansion. They are commonly divided into two classes: bright sirens, observed in coincidence with an electromagnetic (EM) counterpart, and dark sirens, detected without one. Bright sirens have often been considered the main avenue for precision cosmology; however, following the latest observing run of the LIGO-Virgo-KAGRA (LVK) collaboration, the estimates of merger rates of compact objects involving neutron stars…

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gr-qcastro-ph.HEhep-ph

Constraining Ultralight Scalars with Black Hole Binary Mergers in Galactic Nuclei

Majed Khalaf, Eric Kuflik, Alessandro Lenoci, Nicholas Chamberlain Stone, Ofri Telem

Ultralight scalars can form long-lived, macroscopic bound states around spinning black holes, known as superradiance clouds. These clouds provide an additional channel for energy dissipation during close encounters, enhancing the black hole binary formation and merger rates in dense environments such as galactic nuclei. We show that the rate of mergers with mass ratio below $3/10$ in the LIGO-Virgo-KAGRA GWTC-5 catalog can probe ultralight scalars in the mass range $[4\times 10^{-14},10^{-13}]$…

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astro-ph.GA

Little Red Dots are Direct-Collapse Black Hole-Forming Galaxies

Daniel J. Whalen, Muhammad A. Latif, Konstantinos Topalakis, Fergus Cullen, Devesh Nandal, Sadegh Khochfar

"Little Red Dots" (LRDs) at $4 < z < 8$ are one of the most challenging discoveries by JWST to date because their distinctive V-shaped spectra and compact morphologies (100 - 200 pc) defy conventional astrophysical interpretation. Previous attempts to explain LRDs as compact stellar systems, heavily-cocooned black holes with differential flows, supermassive stars, or more exotic objects like 'black-hole stars' either cannot show how they formed, explain the origin of the dense shells needed for…

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astro-ph.GAastro-ph.CO

Clustering-based halo mass assignment for high-redshift galaxies: method, validation, and application to JWST

Seunghwan Lim, Sandro Tacchella, Sara Saleh, Roberto Maiolino, Lily Whitler, Joop Schaye, Evgenii Chaikin, Carlos S. Frenk et al.

We present a clustering-based method for inferring halo masses of high-redshift galaxies, validated using the COLIBRE simulations combined with the HOMA empirical model, which assumes star formation to be proportional to halo accretion rate and is calibrated to JWST observations. Our approach matches the two-point correlation function of galaxies in stellar mass bins to reference halo clustering, establishing the stellar-to-halo mass relation over an optimal radial range 0.5 < r_p/cMpc < 1.0. Va…

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astro-ph.HEastro-ph.COhep-ph

Constraining dark matter using 20-year INTEGRAL/IBIS observations I: Primordial black holes

Jordan Koechler, Pedro De la Torre Luque

Primordial black holes (PBHs) in the asteroid-mass window remain a viable dark matter candidate. In the lower part of this mass range, Hawking evaporation produces electrons and positrons that generate diffuse hard X-ray emission through inverse Compton (IC) scattering on Galactic radiation fields. We present the first search for this signal using a combined spectral and morphological analysis of the 20-year INTEGRAL/IBIS observations. We construct a physically motivated model of the Galactic ha…

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astro-ph.EP

The Mysterious Inspiral of WASP-12b: Why Obliquity Tides Cannot Drive Orbital Decay

Caleb Lammers, Yubo Su, Joshua N. Winn

WASP-12b's orbit is decaying, for unknown reasons. The planet's period is shrinking more rapidly than can be attributed to equilibrium tides or dynamical tides in a main-sequence star. Planetary obliquity tides could be sufficiently dissipative to drive WASP-12b's inspiral, but would also damp the planet's obliquity, halting the decay. Millholland & Laughlin proposed that a nearby, low-mass planet ($\sim 10$ M$_\oplus$) is maintaining a large obliquity for WASP-12b, sustaining the dissipation. W…

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astro-ph.SRastro-ph.HE

Teleparallel torsion and white dwarf structure in \(f(T)=T+ΞT^2\) gravity

Edson Otoniel, Jonathan A. Reboucas, Iarley P. Lobo

We investigate how quadratic torsion modifies the equilibrium structure of white dwarfs in covariant $f(T)=T+ΞT^2$ gravity. Static spherical configurations are calculated with a fixed equation of state for cold carbon matter, including relativistic electron degeneracy and Coulomb lattice corrections. The stellar interior is matched to a vacuum exterior, and the mass is determined from the asymptotic geometry. At fixed central density, negative couplings produce more massive and more compact conf…

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astro-ph.HEgr-qc

Hierarchical Population Inference with Normalizing Flows for Binary Black Holes

Leonardo Iampieri, Simone Mastrogiovanni

Low-dimensional parametric mass models are standard in gravitational-wave population inference, but their rigidity can bias the recovered distribution and the conclusions drawn from it. We present a pipeline in which the source-frame binary-black-hole population in $(z,m_1,m_2)$ is represented by a normalizing flow trained directly through the hierarchical likelihood, with event posterior samples propagating measurement uncertainty and detected injections accounting for selection effects. We res…

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astro-ph.SRastro-ph.EP

An unresolved extreme warm infrared excess toward a nearby low-mass star

Sahin Torlakcik

Gaia DR3 2981818948336660224 is a nearby low-mass star with a substantial warm mid-infrared excess. Identified in a Gaia-2MASS-WISE search, it lies at approximately 127 pc and has an AllWISE W3 signal-to-noise ratio of 33.1. We recover the emission in all 16 available cryogenic exposures over 1.26 d; removing any one exposure leaves the signal intact. The W3 emission is centred close to the propagated stellar position, and the known neighbour 6.1 arcsec away fails to reproduce its morphology. No…

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astro-ph.GA

Learning JWST. I. A Foundation Model for New Population Discoveries and Morphology-Aware Photometric Redshift Measurements in the JADES Survey

Jiani Ding, Minghao Yue, Yongda Zhu, Xiaohui Fan, Yufeng Luo

We present FM-JADES-v1, a self-supervised foundation model for James Webb Space Telescope ({\em JWST}) deep-field science, trained with 482,444 objects from the {\em JWST} Advanced Deep Extragalactic Survey (JADES) Data Release 5 using multi-band imaging and the photometric catalog. The shared embedding space is trained without class labels. We demonstrate that FM-JADES-v1 can serve as a powerful tool for object discovery and improving property measurements using two experiments, blind active di…

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astro-ph.SRastro-ph.GA

A Homogenized Catalogue of Variable Stars in the Globular Cluster M22: Membership, Physical Parameters, and Distance

M. A. Yepez, B. Moreno-Amaro, M. Ornelas-Castañeda, A. Arellano Ferro, D. Deras

We present a photometric analysis of the variable stars in the field of the globular cluster M22 (NGC 6656), using time-series photometry from the literature and from OGLE and Gaia-DR3 data. From a sample of 666 variable stars in the field, we identify 94 as cluster members, including 10 RRab, 17 RRc, 2 Type II Cepheids, 15 SX Phe, 15 SR stars and 22 eclipsing binaries. Fourteen of these members are not included in the Catalogue of Variable Stars in Globular Clusters. Through the Fourier decompo…

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hep-phastro-ph.HEastro-ph.SR

Solar Neutrino Constraints on Inelastic Dark Matter Scattering in Light of Recent LUX-ZEPLIN Observations

Thong T. Q. Nguyen, Tim Linden, Dan Hooper

The LUX-ZEPLIN (LZ) Collaboration recently reported the detection of a single nuclear recoil candidate event with a very high recoil energy. The lack of any corresponding low-energy events motivates models in which dark matter scattering with nuclei has a nontrivial momentum dependence or proceeds inelastically, suppressing the rate of low-energy recoils. In this study, we consider the constraints on inelastic dark matter, including scenarios favored by the LZ event, from the absence of an exces…

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astro-ph.SRastro-ph.EPastro-ph.IM

The Dyn-Atmo Survey: JWST/NIRSpec spectroscopy of dynamical benchmark GJ 758 B

Alexander Madurowicz, Emily Rickman, Daniella Bardalez Gagliuffi, James Mang, Kim Ward-Duong, William O. Balmer, Brendan P. Bowler, Emily Calamari et al.

We present new JWST/NIRSpec IFU high contrast spectroscopic observations of the brown dwarf companion GJ 758 B. Extensive radial velocity monitoring of the primary has enabled high-precision measurements of the companion mass through characterization of their joint orbital dynamics. The combination of prior space- and ground-based photometry and spectroscopic observations in concert with a spectral model-independent mass makes this target an ideal benchmark for calibrating evolutionary models wi…

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astro-ph.SRastro-ph.EPastro-ph.IM

The Dyn-Atmo Survey: High-contrast Imaging Spectroscopy of the Substellar Companion HD 13724 B with the JWST NIRSpec IFU

Kielan K. W. Hoch, Alex Madurowicz, Evert Nasedkin, Emily Rickman, Daniella C. Bardalez Gagliuffi, James Mang, Caroline V. Morley, Christopher A. Theissen et al.

We present the first spectral analysis from the JWST Cycle 3 GO Program #6362, the Dyn-Atmo Survey of dynamical-atmospheric benchmarks, characterizing the atmospheres of directly-imaged companions with dynamical masses and measured orbits. This program has obtained moderate-resolution spectra (R$\sim$2700, 3-5$μ$m) using the NIRSpec/G395H IFU. We observe the T4-dwarf companion, HD 13724 B, companion to a G-type star at a projected angular separation of 0''2. Updated orbital monitoring constrains…

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astro-ph.EPastro-ph.SR

Planetary Accretion Is Less Frequent in Wide Binaries: Evidence from Metal-Enriched White Dwarfs in DESI DR1

Siyi Xu, Laura. K. Rogers, Joan Najita, Boris T. Gänsicke, Paula Izquierdo, Sergey E. Koposov, Christopher J. Manser, Andrew Swan et al.

Binary stars are common in the Galaxy, and understanding how stellar binarity influences the formation and evolution of planetary systems is an active area of research. In this study, we use metal-enriched white dwarfs in wide binaries as tracers of long-lived planetary systems. With Data Release 1 from the Dark Energy Spectroscopic Instrument (DESI), we find that the fraction of cool metal-enriched white dwarfs in wide binaries is 9.8\,$\pm$\,2.1\%, significantly lower (4.7\,$σ$) than the 20.5\…

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astro-ph.HE

Spectral evolution of NS binary system GX 349+2 using AstroSat observations

Garima Tyagi, Suchismito Chattopadhyay, Sree Bhattacherjee, Akash Garg, Ranjeev Misra, Somasri Sen

We present a broadband spectral study of the Sco-like Z source GX 349+2 using AstroSat LAXPC and SXT observations obtained during 2019 and 2024. The X-ray light curves exhibit large variability, and the hardness-intensity diagram traces the characteristic Z-shaped track. Using hardness ratio and intensity, the Z-track is segmented into six regions comprising normal branch, soft apex, and an extended flaring branch. We perform simultaneous broadband spectral fitting in the energy range 0.7-25.0 k…

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astro-ph.HE

Relativistic Magnetohydrodynamics from Myers-Pospelov Lorentz-Violating Electrodynamics

Matheus Duarte, Vitor de Souza

We derive the equations of relativistic magnetohydrodynamics from Lorentz-violating Myers-Pospelov electrodynamics. Starting from the modified fermionic and electromagnetic equations of motion, we employ the covariant Wigner formalism to establish the semiclassical spectral constraints and distribution function, which, combined with Noether's theorem, yield the energy-momentum tensor, particle current, and corresponding conservation laws in the presence of Lorentz violation. The resulting hydrod…

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nucl-thastro-ph.HEnucl-ex

Nuclear-physics-guided Gaussian Processes

Javier Rozalén Sarmiento, Hristijan Kochankovski, Arnau Rios, Àngels Ramos

Gaussian Process Regression is a powerful nonparametric Bayesian method that provides both predictions and principled uncertainty estimates in closed form. The majority of past applications have relied on agnostic priors, but physics knowledge can be systematically encoded into Gaussian Processes through physically-motivated mean functions and kernels. We exploit this capability in the context of nuclear physics, applying physics-guided Gaussian Process Regression to three problems: nucleon-nucl…

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astro-ph.IMhep-exphysics.data-an

Bayesian Superiority in On/Off analysis

Gleb Babenov, Petr Satunin

We present a detailed comparison of Bayesian criteria with three non-informative priors - flat, Jeffreys, and scale-invariant - for testing a signal against an unknown background and compare them with the classical frequentist Li-Ma approach in the On/Off problem. We perform Monte Carlo simulations for various background levels and evaluate the Li-Ma and Bayesian criteria by their Type I error rates. We then simulate a nonzero signal and compare the criteria in terms of Type II error rates. We f…

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astro-ph.IM

The Balloon-borne VLBI Experiment (BVEX) Radio Telescope and Position Tracking System

Felix M. Thiel, Mayukh Bagchi, Laura M. Fissel, Aarchi Shah, Lindy Blackburn, Emily Butler, Rafael Costa, Thomas Emo et al.

Very Long Baseline Interferometry (VLBI) is a technique in radio astronomy that vastly increases the diffraction limited angular resolution of radio observations by correlating simultaneous observations of radio telescopes separated by thousands of kilometers. Ground-based high-frequency VLBI is limited in baseline length by the diameter of the Earth and in sensitivity by molecular absorption of the Earth's atmosphere. One of the ways to improve VLBI is with balloon telescopes, which are much ch…

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astro-ph.GA

The atomic multiphase interstellar medium of galaxies in the COLIBRE simulations

Moa Huppenkothen, Sylvia Ploeckinger, Joop Schaye, Alejandro Benítez-Llambay, Evgenii Chaikin, Filip Huško, Alexander J. Richings, James W. Trayford et al.

We analyse the neutral ISM of galaxies at redshift z=0 in the COLIBRE hydrodynamical simulations and investigate the conditions under which these two gas phases coexist in a narrow range of thermal pressures. COLIBRE galaxies are selected based on the metallicity of their ISM. The median and mass-weighted distributions of thermal pressures of the multiphase ISM are analysed and compared to thermal equilibrium models and observations. The ISM in galaxies with gas metallicities similar to solar va…

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astro-ph.HE

One Precessing Jet Pair, Diverse Core-Collapse Supernova Remnant Morphologies

Jessica Braudo, Noam Soker

We produce a diverse set of observed core-collapse supernova (CCSN)-type morphologies using a precessing pair of opposite jets within the jittering-jets explosion mechanism (JJEM) framework. We conduct a three-dimensional hydrodynamical simulation of a precessing pair of jets that explode a massive star, and find that a single precessing pair of opposite jets can generate S-shaped structures, pipe-spout-blowout features as observed in the Cygnus Loop, multiple apparent pairs of opposite protrusi…

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