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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.EP

Asteroids Impacting the Solar System Planets and the Moon. III. Real Impacts from Known Objects and LSST Discovery Predictions

Qifeng Cheng, Daniel Scolnic

Impact rates predicted using pre-impact source-population models and those inferred from observations disagree by a factor of a few to $\sim200$ across the Solar System planets and the Moon. An exciting opportunity for an additional observational constraint is the discovery of asteroids before impact and their tracking until impact. We evaluate this prospect based on both known objects and forecasts of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). First, we identify impac…

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astro-ph.EPastro-ph.SR

Asteroids Impacting the Solar System Planets and the Moon. II: Comparison with Observational Impact Records

Qifeng Cheng, Daniel Scolnic

Planetary impact rates are difficult to infer from observations alone because impacts are rare, observational records are target-dependent, and converting observed flashes, bolides, and craters to an intrinsic impact rate depends on uncertain selection effects and conversion parameters. Building on the simulations in Paper I, we examine whether observational systematics can explain the order-of-magnitude mismatch between observed and modeled impact rates on Earth, and whether comparable discrepa…

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astro-ph.EP

Asteroids Impacting the Solar System Planets and the Moon. I. Collision Rates from N-body Simulations

Qifeng Cheng, Daniel Scolnic

Previous studies have shown a mismatch between the simulated rate of asteroids impacting the Earth and the observed rate, posing an important problem for planetary defense. Extending this analysis to other planets offers a new opportunity to examine minor body populations and impactor models. We present a unified simulation framework that estimates intrinsic $D\gtrsim10$~m impactor rates on the eight planets and the Moon. We construct size-calibrated source populations of Near Earth Objects (NEO…

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astro-ph.SRastro-ph.EP

Searching for Massive Remnant Planetary System Hosts with White Dwarf Gaia XP Spectra

Lou Baya Ould Rouis, J. J. Hermes, Pierre Bergeron, Simon Blouin, Stefan Arseneau, Tim Cunningham, Joseph A. Guidry, Ciarra Coston et al.

Remnant planetary systems around massive white dwarfs ($M_{\rm WD} > 0.8\,{\rm M}_\odot$) are intrinsically rare and remain poorly characterized. As the evolutionary endpoints of intermediate-mass B- and A-type stars, these white dwarfs provide valuable constraints on the formation and survival of planetary systems around higher-mass progenitors. In the absence of large, dedicated spectroscopic surveys, extremely-low-resolution Gaia XP spectra provide a powerful means of identifying candidate me…

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astro-ph.IMastro-ph.SR

The optical high-resolution spectral archive of the HERMES spectrograph mounted on the 1.2m Mercator telescope

Hans Van Winckel, Saskia Prins, Gert Raskin, Jesus Perez Padilla, Wim Pessemier, Wim De Meester, Maarten Dirickx, Yves Frémat et al.

Context. The HERMES spectrograph is a high-resolution, fibre-fed optical spectrograph of the 1.2m Mercator telescope operated from the Roque de los Muchachos observatory in Spain. HERMES started its scientific operations in June 2009 and has been the workhorse instrument since then. Regular instrument updates have been crucial. They have helped to ensure the continued provision of high-quality spectra. This will continue both now and in the future. Aims. With this contribution we review over 16…

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astro-ph.EPastro-ph.SR

Rotational Mapping and Regional Atmospheric Retrievals of Variable Brown Dwarfs: Application to Luhman 16B and SIMP 0136

Ruizhe Wang, Heather A. Knuton, Julie Inglis, Xianyu Tan

We present a Bayesian framework for converting time-resolved spectroscopy into rotation-inferred regional spectra and atmospheric constraints for variable brown dwarfs. We derive an analytic mapping framework with evidence-optimized regularization and uncertainty propagation by marginalizing over physical parameters and model complexities. We provide methods for selecting characteristic spectral end-members from the inferred surface maps, and highlight the advantage of analyzing these rotation-i…

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astro-ph.EPastro-ph.GA

Multiband Color Monitoring of 3I/ATLAS through Ground-Based Relay Observations

Ariel Graykowski, Bryce Bolin, Laura-May Abron, Franck Marchis, Martin Mašek, Filipp D. Romanov, Ahmed M. Abdelaziz, Dimitrios Athanasopoulos et al.

We present multiband, long-baseline photometric observations of interstellar comet 3I throughout its 2025--2026 apparition using coordinated ground-based global relay observations. Our dataset combines measurements from professional observatories and citizen-operated Unistellar eVscopes distributed worldwide, providing dense temporal coverage from 2025 July 2 through 2026 April 1 and spanning the comet's pre- and post-perihelion trajectory. Broadband photometry was obtained in bandpasses equival…

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astro-ph.EPmath-ph

Comparative analysis of Neural Networks approaches for Initial Orbit Determination of Near-Earth Objects

Francesco Geroni, Roberto Paoli, Riccardo Massidda, Giacomo Tommei

Initial Orbit Determination (IOD) from Very Short Arcs (VSAs) remains one of the most challenging open problems in asteroid surveillance and celestial mechanics. Classical methods require angular observations spanning a sufficient fraction of the orbit, and become ill-conditioned or fail outright when only a single observing night is available, as is the case for most newly discovered Near-Earth Objects (NEOs). We present a comparative analysis of two Neural Network (NN) models that attack the r…

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astro-ph.GA

Stochastic black hole growth tracks stellar mass in ultramassive galaxies

Michele Cappellari, Dieu D. Nguyen, Susan A. Kassin

Over the past three decades, it has been established that galaxy spheroids contain supermassive black holes (BHs) whose masses correlate tightly with the properties of their host galaxies. The most predictive of these correlations is between BH mass and stellar velocity dispersion (the $M_{\rm BH}-σ$ relation), alongside a relation with bulge luminosity or stellar mass (the $M_{\rm BH}-M_\star$ relation). Theoretical models of galaxy evolution predict that for the most massive galaxies, whose la…

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astro-ph.GA

The JWST Ultramassive Galaxy Sample -- II. Supermassive Black Hole Masses for 8 Extreme Early-Type Galaxies via Jeans Anisotropic Modelling of High-Resolution Integral-Field NIRSpec Stellar Kinematics

Michele Cappellari, Dieu D. Nguyen, Susan A. Kassin

We present central supermassive black hole (BH) mass measurements for the JWST Ultramassive Galaxy Sample, comprising 8 galaxies selected from a complete sample of the most massive early-type galaxies in the nearby Universe ($M_\star \gtrsim 2\times10^{12} M_\odot$). Building on the MGE photometric profiles and JWST/NIRSpec stellar kinematics from Paper I, we use the Jeans Anisotropic Modelling (JAM) framework to reconstruct the nuclear dynamics. Given the unique structural properties of these d…

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astro-ph.GA

The JWST Ultramassive Galaxy Sample -- I. Overview, Photometry, and Stellar Kinematics: Selecting Optimal Template Subsets via Non-Negative Matrix Factorization

Michele Cappellari, Dieu D. Nguyen, Susan A. Kassin

We introduce the JWST Ultramassive Galaxy Sample, comprising 8 extreme early-type galaxies ($M_\star \gtrsim 2\times10^{12}\,\mathrm{M}_\odot$) drawn as a representative subset from a comprehensive full-sky census of over 100 such objects. This program aims to dynamically measure their central supermassive black holes (BHs) to probe the extreme high-mass end of BH--galaxy scaling relations, a critical regime where the physical mechanisms governing BH growth and host-galaxy co-evolution are expec…

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astro-ph.GAastro-ph.SR

Stellar Yields of Rapidly Rotating Population III Stars for the High Redshift Universe

Devesh Nandal, Konstantinos Topalakis, Vasilisa Sergienko, Doga Eker, Efe K. Celep, Danielle A. Berg, Daniel J. Whalen, Sophie Tsiatsiou et al.

JWST has revealed rapid nitrogen enrichment in high redshift galaxies, renewing the need for stellar yields that follow metal free stars beyond the main sequence and across their final fates. We present Geneva stellar evolution models of rapidly rotating Pop~III stars with $5 \leq M_{\rm ini}/M_\odot \leq 200$ and $\upsilon_{\rm ini}/\upsilon_{\rm crit}=0.7$, evolved to the end of core O-burning. We calculate gross adopted ejecta masses using fate dependent remnant prescriptions spanning core co…

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astro-ph.HEastro-ph.GA

Euclid: Quick Data Release (Q1) -- Optical hotspots in powerful radio galaxies

M. J. Hardcastle, L. Bisigello, M. Bondi, M. Magliocchetti, L. K. Morabito, J. Petley, F. Ricci, H. J. A. Rottgering et al.

The hotspots of powerful radio galaxies are the sites of high-energy particle acceleration, but radio observations give us limited information on the electron energy distributions that they generate, which affects our overall understanding of their physics and energetics. Optical synchrotron counterparts to radio galaxy hotspots, which probe high electron energies, have been known for many years, but have only been studied in a small number of objects selected as being very bright in the radio.…

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astro-ph.GAastro-ph.SR

Stellar ages from [C/N] in giant stars: applicability and limitations

Giada Casali, Luca Casagrande, Fiorenzo Vincenzo, Andrea Miglio, Melissa Ness, Grazina Tautvaišiene, Laura Magrini, Sven Buder et al.

The [C/N] abundance ratio is a powerful age indicator for giant stars, enabling age estimates for spectroscopic samples where traditional methods are limited. We calibrate a multivariate [C/N]-age-[Fe/H] relationship using 9,122 giant stars observed by Kepler, with asteroseismic ages and APOGEE DR17 abundances. The calibration is performed separately for lower red giant branch (LRGB), upper RGB (URGB), and red clump (RC) stars. We validate the relationships using independent samples from K2, TES…

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astro-ph.HEastro-ph.IMgr-qcnucl-thphysics.plasm-ph

Nonlinearly Causal General-Relativistic Two-Fluid Dissipative Magnetohydrodynamics

Elias R. Most, Samuel J. Dunham

We present a formulation of general-relativistic (GR) 19-moment dissipative magnetohydrodynamics (MHD), capable of handling all first-order dissipative terms (viscosity, heat conductivity, resistivity and Hall terms), as well as all ideal electron degrees of freedom (number density, momentum and energy) in a GR astrophysical two-fluid plasma. We derive necessary and sufficient nonlinear causality conditions for the constrained first-order 19-moment system, as well as both necessary and sufficien…

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gr-qcastro-ph.HEnucl-th

Structure and astrophysical properties of dark energy admixed neutron stars

Juan M. Z. Pretel, Sergio B. Duarte, Mariana Dutra, Odilon Lourenço

The presence of a dark energy (DE) core, made of a Chaplygin dark fluid, is capable of influencing the diverse observable properties of neutron stars (NSs). However, there is also the possibility that NSs could contain a mixture of ordinary nuclear matter and DE. In this perspective, we propose an equation of state (EoS) that includes both normal matter and DE, where a free parameter $f$ quantifies the ratio of DE density with respect to the total energy density. As expected, in the limit $f \ri…

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astro-ph.EPastro-ph.SR

Time-resolved JWST Retrieval Analysis of the Coldest Brown Dwarf: Temperature and Chemical Variations in WISE 0855-07

Harshil Kothari, Caroline V. Morley, Brittany E. Miles, Melanie J. Rowland, Natasha Batalha, Michael C. Cushing, Andrew J. Skemer, James Mang et al.

WISE J0855-07 is the coldest known brown dwarf (estimated Teff~250 K), offering a rare opportunity to probe atmospheric physics in the temperature and mass regime that overlaps directly with exoplanets. At these temperatures, modest perturbations to the thermal structure and chemical abundances can produce measurable changes in the emergent mid-infrared spectrum, making time-resolved spectroscopy a powerful way to test whether the atmosphere is longitudinally and temporally homogeneous. Using Ja…

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astro-ph.SR

GIARPS simultaneous optical and infrared high-spectral-resolution observations of Cepheids I. Limb darkening from cross-correlated radial velocities

N. Nardetto, R. S. Rathour, M. C. Bailleul, V. Hocdé, P. Kervella, G. Bras, W. Gieren, J. Storm et al.

The Baade-Wesselink method, while theoretically applicable for calibrating the distance scale via Cepheids, is not currently employed in the cosmic distance ladder. There are various versions of this method. In all these approaches, the projection factor used to convert the radial into the pulsation velocity remains the limiting quantity. By comparing for the first time simultaneous cross-correlated optical and H-band radial velocities of five Cepheids, we aim to better understand the geometric…

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astro-ph.GA

Supernova origin of galactic turbulence revealed by superbubbles

Fanyi Meng, Chao-Wei Tsai, Jingwen Wu, Sihan Jiao, Mordecai-Mark Mac Low, Zhi-Yu Zhang, Amélie Saintonge, Hui Li et al.

Supernovae (SNe) are among the leading candidates for powering galactic-scale turbulence. SNe drive expanding shells of neutral atomic hydrogen (HI) known as superbubbles. Due to the lack of a sensitive, dynamically complete, galaxy-wide census, superbubbles have not been used to quantify the galactic-scale turbulent energy budget. Here we present a combined Five-hundred-meter Aperture Spherical radio Telescope (FAST) and Jansky Very Large Array HI survey of the Andromeda galaxy (M31), the neare…

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astro-ph.SR

Orbital and stellar parameter determination of eclipsing $β$ Cep pulsators

C. I. Eze, G. Handler, F. Kahraman Aliçavuş, T. Pawar, P. De Cat

Eclipsing binaries provide precise constraints on stellar properties and evolution, making those hosting $β$ Cep pulsators particularly valuable for characterising massive pulsating stars. In this paper, thirteen eclipsing binaries with massive primary components are spectroscopically and photometrically analysed to derive the orbital and stellar parameters, and infer their possible evolutionary status. The systems were spectroscopically observed using SALT HRS, HERMES, CHIRON and a spectrograph…

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physics.ins-detastro-ph.IM

A Deep Neural Network based Level-1 Trigger for the Magnetic Monopole Search in the SCEP Experiment

Changqing Ye, Yunhan Wang, Yifan Qiao, Zhe Cao, Beige Liu, Qing Lin, Lei Zhao

The Search for Cosmic Exotic Particles (SCEP) experiment proposes a multilayer magnetic monopole (MM) detection array with a target exposure of O(10^4) m^2 year. Continuously recording the raw waveforms at this scale would generate approximately O(10) EB of data per year, making full waveform storage impractical. A Level-1 trigger is therefore required to reduce the stored-data volume while retaining rare MM signals. MM waveforms vary with particle velocity and trajectory, so a single filter ker…

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astro-ph.SRastro-ph.HE

SN 2026dix: a nearby, transitional Type IIb/Ib supernova consistent with a warm supergiant progenitor

Tamás Szalai, Schuyler D. Van Dyk, Dominik Bánhidi, Andrea P. Nagy, Réka Könyves-Tóth, Alexei V. Filippenko, Thomas G. Brink, WeiKang Zheng et al.

Understanding the final evolution stages of (very) massive stars and their explosive outcomes, stripped-envelope supernovae (SESNe), represent a long-term challenge for astrophysics. The latest results support a continuous distribution within the traditional SESN subclasses (IIb, Ib, Ic). The nearby ($D \approx 17.5$ Mpc) SN 2026dix seems to be another member of the recently identified group of transitional Type IIb/Ib explosions. A point source is located at the SN position within the uncertain…

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astro-ph.EPastro-ph.SR

JWST MEP - A World Under Spotty Starlight: Detection of CO2 and H2O in the Hot Saturn WASP-52b with JWST NIRSpec G395H

JWST GO 3969 Team, Yanbo Pan, Ryan J. MacDonald, Néstor Espinoza, Bibiana Prinoth, Zafar Rustamkulov, Luis Welbanks, Daniel Kitzmann et al.

Exoplanets orbiting active stars offer distinct challenges for atmospheric characterization with the JWST. Among such worlds, the hot Saturn WASP-52b (Teq $\sim$ 1300 K) orbits an active K-dwarf that complicates transmission spectroscopy via stellar contamination. Here, we present the first JWST NIRSpec G395H (2.8-5.2 $μ$m) limb-averaged transmission spectrum of WASP-52b obtained through the JWST Morning/Evening Program (GO-3969), which aims to measure limb asymmetries across a sample of hot gia…

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astro-ph.SRphysics.space-ph

Stability Analysis of the Proton Hammerhead Distribution Observed by Parker Solar Probe: Linear Theory and Fully Kinetic Simulations under Idealised Conditions

L. Pezzini, J. L. Verniero, F. Bacchini, A. N. Zhukov, G. Arrò, R. A. Lòpez

The non-adiabatic heating of the slow Solar Wind (SW) remains an open problem, with wave--particle interactions as a primary candidate mechanism. Novel in situ Parker Solar Probe (PSP) observations reveal strongly perpendicular anisotropic velocity distribution functions (VDFs), called "hammerhead", correlated with intense wave activity. These VDFs are systematically measured at the Heliospheric Current Sheet (HCS), making the hammerhead an important kinetic signature of the slow SW. In this wor…

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

Core-collapse supernovae 2022prr, 2023ucy, and 2024ljc in the luminous infrared galaxy NGC 6745

K. K. Matilainen, E. Kankare, T. Nagao, T. Reynolds, A. Efstathiou, S. Mattila, C. R. Angus, A. Reguitti et al.

The core-collapse supernovae (CCSNe) 2022prr, 2023ucy, and 2024ljc exploded within the central regions of the nearby luminous infrared galaxy (LIRG) NGC6745. We present our follow-up data with the aim to characterise the spectrophotometric evolution of these CCSNe, determine their host-galaxy extinction, and to define their physical nature. The presented spectrophotometric data set covers the optical and near-infrared region for our three supernovae (SNe). The data are analysed and compared to o…

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astro-ph.HE

Beyond Disk Truncation: X-ray Reverberation Signatures of an Outflowing Corona

Ke Qin, Bei You, Adam Ingram, Barbara De Marco

The corona in black hole X-ray binaries (BHXRBs) is likely dynamic during outbursts. A mildly relativistic outflowing corona has been proposed to explain hard spectra, weak disk reflection, and the higher than expected polarization degree observed in the hard state of X-ray binaries. In this work, we investigate the spectral and timing effects of coronal outflow using Monte Carlo radiative-transfer simulations. The model consists of a geometrically thin, optically thick truncated disk and an ell…

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astro-ph.EP

Some challenges for the long-term survival of Naiad, Neptune's innermost moon

Harrison Agrusa, Matija Ćuk, David Nesvorný, David Minton

The Naiad-Thalassa 73:69 mean-motion resonance implies these moons have co-existed for $\gtrsim$1 Gyr, raising the question of how they survived to the present day. We examine three challenges to Naiad's long-term survival: tidal disruption, heliocentric bombardment, and runaway collisional erosion by planetocentric debris. We constrain Naiad's internal strength requirements from its nominal density and shape, compute present-day impact rates on Neptune's inner moons from heliocentric bombardmen…

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astro-ph.HE

X-ray polarization of the Compton-thin Seyfert galaxy NGC 5506 with IXPE

Daniele Tagliacozzo, Alessandro Leonardo Lai, Andrea Gnarini, Giorgio Matt, Stefano Bianchi, Francesco Ursini, Andrea Marinucci, Alessia Tortosa et al.

We report on the observation of the Compton-thin Seyfert galaxy NGC~5506 performed with the Imaging X-ray Polarimetry Explorer (IXPE). The observation, with a net observing time of 975~ks, was partly simultaneous with \textit{NuSTAR} (52~ks) and \textit{XMM-Newton} (37~ks). Using a simple baseline model with IXPE data only, we find an upper limit on the 2--8~keV polarization fraction at the $99\%$ confidence level: $Π<3.1\%$. We then performed a spectropolarimetric analysis combining data from t…

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astro-ph.HEastro-ph.SR

COBALT-BLUE: a fast and accurate model for gravitational self-lensing binary systems

Danny J. Dixon, Adam Ingram, Matthew J. Middleton, Adam McMaster, Grzegorz Wiktorowicz, Hugh Dickinson, Allison Crossland, Eric C. Bellm et al.

We present COBALT-BLUE, a fast public model for the optical light curve of a luminous star in a non-accreting binary with a compact object. The model includes gravitational self-lensing, Doppler beaming, ellipsoidal variations, eccentric orbital geometry, and wavelength-dependent limb darkening. In sufficiently edge-on systems, it predicts sharp periodic self-lensing flares together with phase-locked orbital modulation outside the flare. We improve upon earlier models by including non-linear lim…

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astro-ph.EP

Faithful Neural Embeddings for 3D Exoplanet Climate Modeling

Amit Reza, Ludmila Carone, Christiane Helling

With the rapid advancement of telescopes like JWST and Ariel, there is an urgent need for efficient 3D climate models to interpret observations of exoplanet atmospheres. Traditional 3D general circulation models (GCMs) are computationally intensive, prompting the development of machine learning (ML) emulators to accelerate simulations. Recent work, such as that by Plaschzug et al. 2026 \cite{plaschzug2026accelerating}, uses a dense neural network (DNN) to predict local gas temperatures and winds…

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