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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GA

SQuIGG$\vec{L}$E: Ubiquitous Cool Gas Outflows with Large Mass-Loading Factors in $z\sim0.7$ Post-starburst Galaxies

Yuanze Luo, Justin S. Spilker, David J. Setton, Timothy Heckman, Rachel Bezanson, Vincenzo R. D'Onofrio, Alex Geiger, Andy D. Goulding et al.

While recent James Webb Space Telescope studies have highlighted cool gas outflows as an important mechanism for rapid quenching at $z\gtrsim2$, such space-based spectroscopic samples remain limited in size. In this work, we search for and characterize cool gas outflows traced by Fe II $λλ$2586,2600 and Mg II $λλ$2796,2803 absorption in post-starburst galaxies (PSBs) at $0.5<z<0.9$, which are accessible to ground-based spectroscopy. Utilizing the SQuIGG$\vec{L}$E survey containing over 1300 PSBs…

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astro-ph.GA

SQuIGG$\vec{L}$E: Spatially resolved NIRSpec Pa$α$ reveals that the most CO-luminous, $z\sim0.7$ post-starburst galaxies exhibit falling---but still active---star formation behind optically thick dust

David J. Setton, Jenny E. Greene, Rachel Bezanson, Katherine A. Suess, Justin S. Spilker, Vincenzo R. D'Onofrio, Elia Cenci, Robert Feldmann et al.

One of the fundamental uncertainties in the study of galaxies at the interface between star formation and quiescence--post-starburst galaxies--is their instantaneous star formation rate. While these galaxies appear quiescent in the rest UV-optical, many of the youngest systems are highly CO luminous, implying dense molecular gas, and potentially star formation. However, their instantaneous star formation rates have proved elusive, as measurements with rest-optical emission lines or UV-to-IR SED…

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astro-ph.GAastro-ph.SR

A solution to the paradox of youth in the Galactic centre

Rodrigo P. Silva, Alexandre C. M. Correia, Tjarda C. N. Boekholt, Paulo J. V. Garcia

The supermassive black hole at the Galactic centre, Sgr A*, is surrounded by an S cluster of young stars. These stars are predominantly B-type stars, but their origin remains uncertain. Unlike massive stars in the Galactic field, which exhibit a binary fraction of about $70\%$, those in the S cluster show a significantly lower fraction. It is key to understand this discrepancy for constraining their formation. We show that the binary deficit arises naturally from dynamical interactions between s…

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astro-ph.GA

H2 emission in the Orion Bar, NGC7023 and the Horsehead Nebula observed with the James Webb Space Telescope

M. Zannese, A. Sidhu, A. Guerras, M. Pound, M. Wolfire, A. G. G. M. Tielens, E. Peeters, E. Habart et al.

Molecular hydrogen (H2), the most abundant molecule in the interstellar medium, is a handy tool to study Photodissociation Regions. The JWST, with its high spatial resolution, sensitivity, and wavelength coverage, provides unique access to the detection and spatial morphology of the H2 rotational and rovibrational lines. Our goal is to analyze H2 line emission detected with JWST in several PDRs (the Orion Bar, NGC7023, and the Horsehead Nebula) to constrain the physical structure of dissociation…

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astro-ph.IMastro-ph.GAastro-ph.SR

MATISSE-py: a high-level Python interface for efficient, automated VLTI/MATISSE data reduction

A. Soulain, A. Matter, P. Berio, F. Millour, B. Lopez, R. Petrov, S. Lagarde

The Multi AperTure mid-Infrared SpectroScopic Experiment (MATISSE) at the Very Large Telescope Interferometer (VLTI) delivers rich mid-infrared interferometric datasets that are reduced through a robust, multi-stage ESO pipeline. In its native form, however, the reduction relies on command-line calls to esorex, hand-edited set-of-files (SOF) and configuration files, and manual iterations that are difficult to automate, reproduce, or integrate into modern Python workflows. We present MATISSE-py,…

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astro-ph.EP

N-Body Dynamics as a Mechanism for Mean Motion Resonance Formation in the Post-Gas Era

Kai Sun, Sheng Jin, Dong-Hong Wu, Meijuan Wang

Mean motion resonances (MMRs) are traditionally thought to form during the gas-rich phase of protoplanetary disks via disk-driven migration. Whether MMRs can form solely through collisional damping after disk dispersal has not been systematically investigated. To study MMR formation in the post-gas-disk era, we perform a large suite of N-body simulations, each containing 10,000 planetesimals around an M-dwarf star and evolving over 10 Myr. We compare two groups of simulations that differ only in…

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physics.geo-phastro-ph.EP

From Image Morphology to Multiphysics Earth Posteriors

Ziye Yu, Xin Liu, Yuqi Cai

Structural learning and physical-property inference can draw on different sources of knowledge. We learn morphology from 33,140 natural, satellite, and texture images, without geological training models, then infer Earth properties from physical observations. Identical frozen weights map 128 coordinates into each $256\times256$ compressional-velocity, shear-velocity, or density field. Fixed adapters assign physical meaning; observation-specific likelihoods determine new posteriors without retrai…

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astro-ph.GAastro-ph.SR

ATLASGAL: The HCN-IR Star Formation Relation for the Milky Way

I. I. Grozdanova, J. S. Urquhart, W. -J. Kim, F. Wyrowski, T. Csengeri, A. Karska, A. Giannetti, D. Colombo et al.

We examine the relation between star formation and dense gas, traced by HCN(1-0), using a sample of 343 Galactic clumps spanning the full range of evolutionary stages representative of high-mass and cluster formation, including quiescent, protostellar, young stellar object (YSO), and HII regions. Earlier Galactic studies, based primarily on luminous HII regions, reported a linear correlation between infrared (IR) and HCN luminosities, consistent with extragalactic surveys, and interpreted it as…

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cs.LGphysics.space-ph

Self-Supervised Representation Learning: From Spectral Foundation Models to Auroral Emission Spectra

Matthieu Le Lain, Gaël Cessateur, Sébastien Lefèvre

Auroral spectrographs such as the Auroral Spectrograph In Skibotn (ASIS) record hundreds of thousands of emission spectra, but only a few hundred can be labelled by an expert. To exploit the rest, we pretrain a 1D Vision Transformer with a masked autoencoder on 223,000 unlabelled spectra. Without labels, its representation recovers the emission-line intensity ratios that physicists use to diagnose the precipitating particles (R^2 0.91 vs. 0.77 for an untrained control) and, under one linear prob…

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astro-ph.EPastro-ph.SR

JWST detection of methane emission from a young brown dwarf

K. L. Luhman, C. Alves de Oliveira, J. K. Faherty, B. C. Smith

In recent studies, we have used low-resolution spectroscopy (R~100) with the James Webb Space Telescope (JWST) to uncover low-mass brown dwarfs (2-10 MJup) in the young cluster IC 348 that exhibit the so-called 3.4um absorption band from aliphatic hydrocarbons. Atmospheric models have not predicted the presence of that band in brown dwarfs at any age. Instead, methane absorption was expected in the coolest newborn brown dwarfs, but it was not detected. We have performed JWST spectroscopy at high…

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physics.space-phastro-ph.EPcs.CV

Electric Potential Patterns Forecasting in the Southern Hemisphere with Deep Learning Techniques

Francesco Pio Ramunno, Simone Mestici, Igino Coco, Maria Walach, Stefano Massetti, Maria Federica Marcucci, Brandon Panos, André Csillaghy et al.

Space weather disturbances driven by the solar wind can degrade satellite navigation, disrupt radio communications, and threaten power infrastructure, making accurate forecasting of the high-latitude ionosphere's response a critical operational need. Existing approaches, empirical climatological models and physics-based magnetohydrodynamic simulations, either smooth out the ionosphere's time-dependent, non-linear response or are too computationally expensive for real-time use, while prior machin…

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gr-qcastro-ph.IM

Architecture Acceleration of Machine Learning Gravitational Waveform Surrogate Models

Adriano Frattale Mascioli, Lorenzo Piccari, Saulo Albuquerque, Gabriele Demasi, Giulia Capurri, Massimo Lenti, Angelo Ricciardone, Barbara Patricelli et al.

Accurate and computationally efficient waveform models of compact binary coalescences are a fundamental requirement for gravitational wave data analysis. This work presents differentiable and hardware-accelerated implementations of the machine-learning surrogate models mlgw and mlgw-bns within the JAX ecosystem. The proposed framework enables JIT compilation, vector paralellization, native GPU acceleration, and automatic differentiation, while preserving the original surrogate training infrastru…

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astro-ph.SRastro-ph.GAastro-ph.IM

The NEMESIS general YSO catalogue - I. Supervised classification with deep learning methods

G. Marton, M. Madarász, J. Roquette, M. Audard, I. Gezer, D. Hernandez, O. Dionatos

In modern large-scale surveys, young stellar objects (YSOs) are mostly identified by the infrared excess in their spectral energy distributions (SEDs). To this end, YSO identification and classification were mostly based on certain colours, resulting in wavelength-specific methods. Using all available data allows us to construct a uniformly classified YSO catalogue by applying the same identification method to heterogeneous samples, reducing systematic differences and enabling more consistent st…

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astro-ph.COastro-ph.GAastro-ph.HE

Probing the cosmic web with fast radio bursts: II. Scintillation

Sharon Lapiner, Nir Mandelker, Paz Beniamini, S. Peng Oh

We consider the formation of multiphase gas in cosmic web objects (CWOs) through cooling and fragmentation within the shock-heated medium of cosmic sheets and filaments, and the circumgalactic medium (CGM) of haloes. This leads to dense, cool ($\sim10^{4}\,\mathrm{K}$), small-scale cloudlets in pressure equilibrium with their surroundings. Such ionized overdensities can affect the propagation of radio waves emitted by fast radio bursts (FRBs), allowing us to probe the small-scale structure in CW…

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astro-ph.GAastro-ph.SR

Simulating tidal disruption events in nuclear star clusters

Philip Cho, Kai Wu, Francesco Flammini Dotti, Taras Panamarev, Shuo Li, Shiyan Zhong, Klaus Reuter, Rainer Spurzem et al.

Context. Nuclear star clusters (NSCs) and supermassive black holes (SMBHs) often coexist at the centers of galaxies, engaging in complex dynamical interactions that influence SMBH growth. Stars that approach the SMBH too closely are tidally disrupted, and a fraction of their debris is accreted onto the black hole. Such events may contribute to SMBH growth in gas-deficient galaxies. Aims. Our work aims to improve the theoretical framework for understanding the mass accretion of stellar debris fol…

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nucl-thastro-ph.HEhep-ph

Set Transformer inference of the neutron star equation of state from stellar observations

Márcio Ferreira, Valéria Carvalho, Michał Bejger, Constança Providência

We develop a permutation-invariant Set Transformer to reconstruct the equation of state (EoS) of dense matter from variable-size, unordered sets of neutron star (NS) observations. The model takes stellar masses together with radii, tidal deformabilities, or both, and predicts either the pressure $P(n)$ or the sound speed $c_s^2(n)$ on a fixed density grid, along with density-dependent uncertainties. Nothing in the architecture prescribes which star informs which density: self-attention couples a…

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astro-ph.GAastro-ph.SR

AKARI near-infrared spectroscopy of circumstellar hydrocarbon dust associated with young stellar objects

Yuki Kuroda, Hidehiro Kaneda, Natsuko Izumi, Takuma Kokusho, Shinki Oyabu

We investigate the processing of the circumstellar polycyclic aromatic hydrocarbons (PAHs) associated with young stellar objects (YSOs) through their stellar activities. We analyze the AKARI near-infrared (2.6$-$4.4 $μ$m) long-slit spectral data of 10 YSOs, focusing on the aromatic feature at a wavelength of 3.3 $μ$m and the aliphatic features at 3.4$-$3.6 $μ$m. The spectral fitting results show large variations from target to target in the flux ratio of the aliphatic to aromatic features, the s…

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physics.plasm-phastro-ph.HE

Bayesian inference of non-Maxwellian distribution functions from collective Thomson scattering spectra

Kentaro Sakai, ByungJun Kang, Akito Nakano, Takeo Hoshi

We investigate Bayesian inference of non-Maxwellian electron distribution functions from collective Thomson scattering (CTS) spectra. We represent distribution functions using multiple candidate models of different complexity and perform inference on synthetic spectra generated from known non-Maxwellian distribution functions. Our analysis demonstrates that a sufficiently flexible model can approximate the overall shape of the ground-truth distribution function. The most plausible model is ident…

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astro-ph.HE

Convolutional non-parametric Gamma-Ray Signal and Background Separation

Scarlet Betterman, Emmanuel Moulin, Martin White

In very-high-energy gamma-ray astronomy, signals must be separated from the residual background which arises from misidentified cosmic-ray protons. Building on previous work, we introduce an ensemble of variational autoencoders that aims to perform automatic signal-background separation with minimal assumptions that include separability of the spatial and energy distributions in both the signal and background, with no prior specification of the number of components or the point-like/diffuse natu…

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astro-ph.EP

TS23/McDonald and FIES/NOT strike again. Two new warm Jupiter systems and outer companions in a third

E. Knudstrup, D. Gandolfi, W. D. Cochran, M. Endl, P. MacQueen, T. Pugh, M. S. Lundkvist, C. M. Persson et al.

Warm Jupiters (gas giant planets with orbital periods of P$\sim$8-200 d) are thought to be largely unaffected by the tidal interactions that can erase information about the dynamical histories of hot Jupiters. Their orbital eccentricities ($e$) and stellar obliquities are therefore expected to be preserved, making them valuable probes of giant-planet formation and migration. Our aim is to identify and characterise transiting warm Jupiters in order to expand the sample of well-characterised syste…

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cond-mat.softastro-ph.EP

A Bonded-Particle Discrete-Element Model with Self-Gravity for the Collision and Reaccumulation of Rubble-Pile Asteroids: Formulation and Numerical Protocol

Yohann Trivino

I present a discrete-element approach developed to study the collisional and gravitational evolution of small self-gravitating granular aggregates. Each body is represented as a composite of cohesively bonded spherical grains, so that fragmentation and reaccumulation emerge from the microscopic competition between short-range dissipative contact forces, an irreversible bond-breaking criterion, and pairwise Newtonian self-gravity summed over every particle pair, including those internal to a sing…

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astro-ph.SRastro-ph.IM

Beating and coupling in pulsating stars: a unified Fourier description and observational diagnostics

József M. Benkő, Emese Plachy

Long-term amplitude and phase variations in pulsating stars produce side peaks or multiplets in the Fourier spectrum of the light curves around the pulsation frequency and its harmonics. Such structures are often attributed to modulation, although linear beating and the non-linear coupling of close oscillations can also produce similar patterns. We develop a unified analytical Fourier description of these alternatives and identify observational relations that retain discriminatory power when the…

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astro-ph.SRastro-ph.GAastro-ph.HEphysics.atom-ph

Near-infrared spectra of chemically peculiar stars and applications to kilonova spectra

Nanae Domoto, Masaomi Tanaka, Wako Aoki, Salma Rahmouni, Tomoyuki Kudo, Hiroki Harakawa, Teruyuki Hirano, Takayuki Kotani et al.

Kilonova spectra provide information on rapid neutron-capture nucleosynthesis in neutron star mergers. However, it remains challenging to identify individual elements in kilonova spectra, primarily due to incomplete atomic data for heavy elements at near-infrared wavelengths. Recent work demonstrated that spectra of chemically peculiar stars offer excellent laboratory for studying kilonova spectra. In this paper, to expand our understanding of strong transitions of heavy elements at near-infrare…

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astro-ph.GA

KBSS-InCLOSE II: First Detailed Insights on the Inner CGM of Low-Mass $z\sim2.3$ Galaxies

Evan Haze Nunez-Cravin, Charles C. Steidel, Gwen C. Rudie, Evan N. Kirby, Charis M. Hall, Nikolaus Z. Prusinski, Zhuyun Zhuang, Yuanze Ding et al.

We present results from an extension to the Keck Baryonic Structure Survey (KBSS) that focuses on the Inner Circumgalactic Medium (CGM) of QSO Line Of Sight Emitting galaxies at z$\sim$2.3 (InCLOSE). We analyze two low-mass galaxies $\log{(\rm{M_*} / \rm{M_\odot})} \leq 9$ that are within small a projected distance of a QSO $D_{\rm tran} \leq 50~{\rm kpc}$ ($D_{\rm tran} /R_{\rm vir} \leq 0.75$). One galaxy is detected as a bright Lyman- Emitter with Keck/KCWI (confirmed with follow-up Keck/MOSF…

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astro-ph.EPastro-ph.GA

On the Compositions of Interstellar Objects

Matthew J. Hopkins, Michele T. Bannister, Bertram Bitsch, Chris Lintott, John C. Forbes

As physical samples of distant planetary systems, the compositions of interstellar objects (ISOs) should correlate with the properties of their diverse parent stars. We combine a chemical partition model with a sample of stellar elemental abundances from APOGEE DR17 to predict the abundances of commonly-observed cometary volatiles in ISOs. We find that the compositions of ISOs vary significantly between different stars. In particular, we predict a strong correlation between an ISO's ammonia abun…

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astro-ph.HE

Long-term X-ray variability of the NLS1 Ark 564

Neha P R, Nikita S Arun, Savithri H. Ezhikode, Ranjeev Misra, Bari Maqbool, Jeena K, Joe Jacob

We present a systematic spectral study of the X-ray emission from the Narrow- Line Seyfert 1 (NLS1) galaxy Ark 564 using Swift/XRT observations spanning sixteen years. The source exhibits significant variability in both the soft and hard X-ray bands, along with a strong positive correlation between them, indicating a closely coupled emission mechanism within the accretion flow-corona system. A simple absorbed power-law model is statistically insufficient to describe the spectra, confirming the p…

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astro-ph.SR

BS Cassiopeiae: A Contact Binary with Starspot-Driven Variability and Evidence for Additional Components

Min-Ji Jeong, Chun-Hwey Kim, Kyeongsoo Hong, Mi-Hwa Song, Hye-Young Kim, Jang-Ho Park, Cheongho Han, Joh-Na Yoon et al.

We present a comprehensive photometric and spectroscopic analysis of the contact eclipsing binary BS Cas, based on 22-yr multi-site light curves and 2-yr high-resolution spectra. The long-term photometry shows pronounced year-to-year changes in the light-curve shape, including eclipse-depth reversals between the primary and secondary minima and variations in the O'Connell effect. The first double-lined radial-velocity (RV) curves of BS Cas are derived from the spectra using broadening-function (…

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astro-ph.EP

Pulsed Accretion onto Eccentric Binaries in Highly Misaligned Circumbinary Disks

Ruiqi Yang, Jeremy L. Smallwood, Shang-Fei Liu, Alessia Franchini

We present three-dimensional smoothed particle hydrodynamics simulations of highly misaligned circumbinary disks (CBDs) around moderately eccentric equal-mass binaries ($e_\mathrm{b}=0.5$). We show that the binary accretion is modulated on the binary orbital period and exhibits two pulses near periastron. The dominant pulse peaks before periastron for an initial binary-disk misalignment of $60^\circ$, shifts to after periastron at $90^\circ$, and occurs at an even later post-periastron phase at…

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astro-ph.EP

Pulsed Accretion onto Eccentric Binaries in Highly Misaligned Circumbinary Disks

Ruiqi Yang, Jeremy L. Smallwood, Shang-Fei Liu, Alessia Franchini

We present three-dimensional smoothed particle hydrodynamics simulations of highly misaligned circumbinary disks (CBDs) around moderately eccentric equal-mass binaries ($e_\mathrm{b}=0.5$). We show that the binary accretion is modulated on the binary orbital period and exhibits two pulses near periastron. The dominant pulse peaks before periastron for an initial binary-disk misalignment of $60^\circ$, shifts to after periastron at $90^\circ$, and occurs at an even later post-periastron phase at…

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astro-ph.SRastro-ph.GA

A Sample of Long-Period Binaries with Dormant Compact-Object Candidates from LAMOST DR13 MRS and Gaia DR3

Junxing Zhou, Wei-Min Gu

Identifying dormant compact objects in non-interacting binaries is crucial for constraining the hidden population of stellar remnants. We present a systematic search for long-period compact-object candidates by combining Gaia DR3 astrometry with multi-epoch LAMOST DR13 medium-resolution spectroscopy. Starting from sources with elevated RUWE values, we required at least five LAMOST spectroscopic epochs and peak-to-peak RV variations exceeding 20 km/s. After RV extraction, orbital fitting, and sub…

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