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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.EP

Improved Constraints on the Surface of LHS 3844 b from its Mid-Infrared Spectrum

Kimberly Paragas, Heather A. Knutson, Renyu Hu, Bethany L. Ehlmann, Aishwarya R. Iyer, Sebastian Zieba, Laura Kreidberg

The thermal emission spectra of terrestrial exoplanets provide a window into their surface compositions and corresponding geological processes. Close-in, rocky planets orbiting M dwarfs are ideal targets for these studies, as observations have shown that most have little to no atmosphere. LHS 3844 b is an ultra-short period super-Earth orbiting a nearby M dwarf, and is the most favorable target that does not have a dayside magma ocean. We present an updated JWST MIRI/LRS emission spectrum ($5-12…

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

Constraining exoplanet population parameters with Kepler and simulation-based inference

Chloé Padois, Friedrich Anders, Daniel del Ser

In the context of the rapidly growing field of galactic exoplanet population studies, we present an exoplanet simulator capable of generating synthetic populations for millions of stars in a few seconds (Padois et al., 2025). Our framework combines observed exoplanet detections with the latest planetary formation models, incorporating dependencies between host star properties and planet occurrence rates, orbital period distributions, and other key demographic features. However, many model parame…

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astro-ph.GA

Torsionally excited methanol in massive young stellar objects: The role of the mid-IR radiation field

C. Sanna, S. Leurini, A. Giannetti, E. Schisano, L. Testi, S. Molinari, J. S. Urquhart, T. Pillai et al.

Observing the earliest stages of high-mass star formation in the mid-infrared (mid-IR) is challenging because the extinction is high and the resolution limited. Millimeter vibrationally and torsionally excited transitions of several molecules have been proposed as indirect probes of local mid-IR radiation fields around young stellar objects (YSOs). We investigate the excitation and spatial distribution of torsionally excited methanol ($\mathrm{CH_3OH}$) in 12 high-mass star-forming clumps in dif…

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astro-ph.HEastro-ph.SRgr-qcnucl-th

Joint Mass-Radius and Magnetic-Geometry Inference of PSR J0740+6620

Chun Huang, Tuomo Salmi, Alexander Y. Chen

X-ray pulse-profile modeling can measure neutron-star radii, but its physical interpretation remains limited by the largely phenomenological description of the surface hotspots. Here we connect the X-ray hotspots directly to the pulsar magnetospheric structure and jointly infer the mass, radius, and magnetic geometry of the massive millisecond pulsar PSR J0740+6620 from \emph{NICER} and \emph{XMM-Newton} observations. Using a GPU-accelerated implementation, we compare two low-dimensional magneti…

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astro-ph.SRastro-ph.EPastro-ph.HE

Detection of fine-structured radio bursts during a superflare on EQ Peg

Zhanhao Zhao, Xin Cheng, Yuankun Kou, Guoyin Chen, Hao Ning, Yao Chen, Baolin Tan, Keping Qiu et al.

Superflares are frequently observed on magnetically active stars, particularly on active M-dwarfs, thereby influencing the habitability of nearby exoplanets. However, the causes of superflares remain unclear. Here, combining FAST and TESS, we detected a finely structured decimetric radio burst appearing as groups of spikes during a white-light superflare (total bolometric energy $\sim 10^{33} \ \mathrm{erg}$) on the M-dwarf binary EQ Peg on September 8th, 2022. The most significant ones appeared…

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astro-ph.GAastro-ph.COastro-ph.IM

A Full-Sky SPHEREx Map of Integrated 3.3 and 3.4 μm PAH Emission

Roke Cepeda-Arroita, Clive Dickinson, J. Alberto Rubiño-Martín, Ricardo T. Génova-Santos, Gabriel A. Hoerning, Stuart E. Harper, Debabrata Adak

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the interstellar medium and are among its smallest carbonaceous grains. Their infrared emission bands trace this small-grain population together with the interstellar radiation field that excites it, and are widely used to diagnose photodissociation regions, dust processing and star formation. We present full-sky maps of the integrated radiance of the 3.3 $μ$m aromatic C-H stretch and the adjacent 3.4-3.5 $μ$m aliphatic complex, from SPHE…

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astro-ph.IMastro-ph.HE

An End-to-End Numerical Framework for Tidal Disruption Events with AthenaK

Hong-Xuan Jiang, Mengqi Yang, David A. Velasco-Romero, Fangyuan Yu, Jing-Ze Xia, Xinyu Li, Yosuke Mizuno

In a tidal disruption event (TDE), a star is torn apart by the tidal field of a black hole (BH), and its bound debris returns over many orbits to form an accretion disk. We present a framework built on the GPU-accelerated finite-volume code AthenaK that follows these stages in a single simulation with self-gravity throughout. We extend AthenaK with a moving simulation frame, restart remapping between domains, a multigrid Poisson solver on the adaptive mesh, a tabulated hydrogen-helium equation o…

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astro-ph.IMastro-ph.HE

An End-to-End Numerical Framework for Tidal Disruption Events with AthenaK

Hong-Xuan Jiang, Mengqi Yang, David A. Velasco-Romero, Fangyuan Yu, Jing-Ze Xia, Xinyu Li, Yosuke Mizuno

In a tidal disruption event (TDE), a black hole (BH) tears apart a star, whose bound debris returns over many orbits to form an accretion disk. We present a framework built on the GPU-accelerated finite-volume code \texttt{AthenaK} that follows these stages in a single simulation with self-gravity throughout. We extend \texttt{AthenaK} with a moving frame, restart remapping between domains, an adaptive-mesh multigrid Poisson solver, a tabulated hydrogen--helium equation of state including recomb…

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astro-ph.GA

The orbital dynamics of the LMC and SMC about the Milky Way

Gurtina Besla, Nitya Kallivayalil

This review summarizes the changing observational and theoretical landscape that has led to rapid developments in our understanding of the orbital history of the Milky Way's most massive satellite galaxies, the LMC and SMC. The determination of high precision center-of-mass proper motions for the Clouds and their environs, coupled with new insights into the structure of dark matter halos from cosmological simulations, indicates that the Clouds are recent additions to the Milky Way's satellite sy…

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physics.plasm-phastro-ph.SRphysics.space-ph

Effects of Alfvénicity on the Compressible Energy Cascade in Magnetohydrodynamic Solar Wind Turbulence: Evidence from Parker Solar Probe, Solar Orbiter, and WIND observations

Nahuel Andrés, Carlos A. Gonzalez, Norberto Romanelli

The compressible MHD energy cascade in the solar wind is shaped by Alfvénicity, plasma fluctuations, and proton temperature, yet how these factors regulate the relative weight of compressible and incompressible energy transfer across heliocentric distances remains poorly understood. We apply compressible and incompressible exact relations to a large sample of 2-hour intervals from WIND (1~au), Parker Solar Probe ($ 0.75$) or non-Alfvénic ($|σ_c|<0.25$) and by wind speed, and examine the Yaglom-l…

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astro-ph.SR

Solar spicule population properties inferred from IRIS Mg II k off-limb spectra using likelihood-free Bayesian inference

Jiri Stepan, Stanislav Gunar, Akiko Tei, Petr Heinzel

Solar spicules are ubiquitous and strongly overlapping in off-limb observations, which complicates the interpretation of individual events. We aim to infer population-level properties of spicules from IRIS Mg~II~k off-limb spectra using a forward model that explicitly accounts for line-of-sight superposition and instrumental effects. We construct a stochastic three-dimensional spicule-population model and synthesize Mg II k spectra with radiative transfer, including instrumental degradation and…

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astro-ph.HEastro-ph.IMhep-ex

ALMA - CTAO synergies

Paola Andreani, Maria Diaz-Trigo

This article aims to raise awareness within the ESO astronomical community of the scientific opportunities offered by the upcoming Cherenkov Telescope Array, CTAO, highlighting cases where combining millimetre/submillimetre capabilities of the Atacama Large Millimeter / submillimeter Array, ALMA with the CTAO's very high energy, TeV, observations enables new avenues for discovery. Many astrophysical sources and environments exhibit emission processes detectable in both regimes; however, the syne…

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astro-ph.SR

Near-infrared periodicity in the SPICY catalog. True young stellar objects versus contaminants

C. Ordenes-Huanca, A. Bayo, M. Zoccali, V. Guzmán, A. Rojas-Arriagada

Infrared (IR) large-sky surveys allow study of how localized star formation is, enabling searches for young stellar objects (YSOs) not only at the centers of known stellar nurseries but also across the Galactic plane. However, these spatially unbiased searches suffer from contamination, most notably from dusty asymptotic giant branch (AGB) stars characterized by long-period variability. Using time-series analysis, and taking advantage of the different variability timescales of YSOs against long-…

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astro-ph.HEastro-ph.CO

Shaping binary black hole merger efficiency with gravitational wave observations

Michele Bosi, Lumen Boco, Stefano Torniamenti, Stefano Rinaldi, Cecilia Sgalletta, Michela Mapelli, Carlo Baccigalupi, Andrea Lapi et al.

Gravitational wave (GW) astronomy offers unprecedented insights into binary black hole (BBH) coalescence. However, many of the key quantities involved remain inaccessible to direct observations. The BBH merger rate density is deeply linked to both the merger efficiency and the distribution of delay time between binary formation and merger, neither of which is directly constrained by observations. Disentangling their impact on the merger rate represents a highly non-trivial endeavour. Here we pre…

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astro-ph.IM

On-sky commissioning and technical performance of Proto-NUX at Pic du Midi

Rasjied Sloot, Rudy Wijnands, Steven Bloemen, Hans Ellermeijer, Alexander Hoogerbrug, Rik ter Horst

The Near-Ultraviolet eXplorer (NUX) is a proposed ground-based observing facility designed to expand near-ultraviolet (NUV) astronomy by enabling observations in the 300--350 nm range from Earth. The full system is intended to consist of four modified 36 cm Celestron RASA telescopes with custom NUV-optimized optics and UV-sensitive CMOS detectors, providing a total field of view of about 67 square degrees for high-cadence searches for fast, hot transients. To validate this concept, a single-tele…

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astro-ph.EPastro-ph.IM

Detecting atmospheres in the presence of stellar contamination: an empirically calibrated framework applied to four JWST/NIRSpec PRISM transits of TRAPPIST-1c

Alexander D. Rathcke, Lars A. Buchhave

Transmission spectroscopy of rocky exoplanets orbiting late M dwarfs is limited by stellar contamination rather than photon noise. We present a framework for this contamination-dominated regime, fitting all transit epochs jointly with a Gaussian process per epoch for the time-varying stellar contamination and a single atmospheric model shared across epochs. We use pure CO$_2$, H$_2$O, and CH$_4$ models scaled by their peak-to-trough amplitude, allowing us to measure how large a signal must be to…

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astro-ph.HEastro-ph.SR

Fast and furious -- High-velocity features of Ca and Si in the spectra of Type Ia supernovae

Zsófia Bora, József Vinkó, J. Craig Wheeler, Réka Könyves-Tóth, G. H. Marion

High velocity absorption lines of Ca II and Si II (high-velocity features, HVFs) are common in the early spectra of Type Ia supernovae (SNe Ia), but their physical origin is still poorly understood. We used 181 optical spectra of 56 SNe Ia that show HVFs in at least the Ca II NIR triplet to better understand the nature of HVFs. To model the profiles of HVFs we applied Gaussian fitting as well as spectrum synthesis modeling with the SYNOW code. We found that Gaussian fitting usually underestimate…

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astro-ph.SR

Common Envelope Evolution: Too stochastic to be deterministic

Noam Soker

I argue for significant stochastic behavior in the common envelope evolution (CEE) of cool giants and main-sequence companions to the degree that it is almost impossible to know the exact CEE outcome of an individual binary system from the average properties of the stars and their initial orbit. I start with two observational properties of post-CEE planetary nebulae: many have jet-shaped morphologies, and they show a wide variety of morphologies. The first suggests that the standard CEE model sh…

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astro-ph.GA

Thermally irreversible sulfur chemisorption on silicate grains as a major sulfur reservoir in molecular clouds

Ni-En Sie, Masashi Tsuge, Yasuhiro Oba, Germán Molpeceres, Kenji Furuya, Naoki Watanabe

Sulfur (S) chemistry in the interstellar medium remains poorly constrained due to the longstanding "missing sulfur" problem, where a significant fraction of cosmic sulfur in molecular clouds remains unidentified. To gain a comprehensive understanding of S chemistry in the interstellar medium, its behavior on interstellar dust grains must be clarified. Here, we experimentally investigated the surface elementary processes of S atoms under conditions mimicking interstellar molecular clouds. Our in-…

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astro-ph.HEastro-ph.GA

X-ray measurements of the elemental abundances for the diffuse emission in the nuclear starburst galaxy NGC 3079

Jiejia Liu, Junjie Mao, Shuinai Zhang, Guan-Fu Liu, Rui Huang, Wei Cui

Outflows driven by feedback leave imprints on a galaxy's diffuse X-ray emission. Elemental abundances provide key diagnostics of feedback-driven chemical enrichment. We present a spectroscopic study of the diffuse X-ray emission in NGC 3079 using XMM-Newton RGS and EPIC, focusing on the nuclear region and the extended galactic-scale superbubble (GSB). We analyzed the high-resolution RGS spectrum of the central $\sim4~\rm kpc$ region, encompassing the $\sim1~\rm kpc$ nuclear superbubble (NSB), an…

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astro-ph.GA

GA-NIFS: sRMS, a new method for disentangling resolved and unresolved emission in integral field spectroscopy. Application to distant quasars

Michele Perna, Santiago Arribas, Carlota Prieto-Jiménez, Isabella Lamperti, Lorenzo Ulivi, Hannah Übler, Giovanni Cresci, Bruno Rodríguez Del Pino et al.

The interpretation of AGN emission-line profiles in type1 AGN is often complicated by the dominance of bright, spatially unresolved nuclear continuum and broad-line region (BLR) emission over narrower and blended components from the narrow-line region (NLR) and the host galaxy. This remains challenging even with integral-field spectroscopy (IFS), as the relevant spatial variations can occur on scales smaller than the angular resolution, particularly in the compact host of distant AGN. We introdu…

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astro-ph.SRastro-ph.GA

Abundance analysis of three new extremely metal-poor stars, including one CEMP-s star

P. François, T. Suda, S. Wanajo, E. Caffau, P. Bonifacio, W. Aoki, S. Yamada, M. Y. Fujimoto et al.

We report a detailed abundance analysis of three extremely metal-poor (EMP) stars thanks to spectra obtained with the high-dispersion spectrograph (HDS) at the Subaru telescope. The aim is to observe a sample of EMP candidate stars selected from the Sloan Digital Sky Survey (SDSS) and determine their detailed chemical composition. High-resolution spectra of three faint turn-off stars using HDS on the Subaru telescope were acquired.We used standard 1D models to compute the abundances of several e…

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astro-ph.GAastro-ph.HE

Fooled by mass? Recovering the $Γ-λ_{Edd}$ relation of quasars from their X-ray variability

Matilde Signorini, Andrea Sacchi, Bartolomeo Trefoloni, Matteo Guainazzi, Elisabeta Lusso, Emanuele Nardini, Chiara Niccolai, Federica Ricci et al.

We measure the relation between the X-ray photon index $Γ$ and the Eddington ratio $λ_{Edd}$ in unobscured type-1 quasars, using as parent sample the cross-match of the SDSS DR16Q catalogue with the 4XMM-DR14 serendipitous catalogue. After cleaning the sample of potential observational biases, we obtain 7835 objects, one order of magnitude larger than most previous analyses in the literature. A single regression of $Γ$ against $\logλ_{Edd}$, with single-epoch virial black-hole masses, returns sl…

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astro-ph.EP

TOI-6981 b: a transiting sub-Neptune at the water ice line

Madison G. Scott, Amaury H. M. J Triaud, Emily K. Pass, Aleyna Adamson, Karen A. Collins, Khalid Barkaoui, Allyson Bieryla, Adam J. Burgasser et al.

We present TOI-6981 b, a cold (Teq= 170.0 +/-4.5 K, assuming an Earth-like albedo) sub-Neptune (Rb=2.40+/-0.10 R_oplus) on a 60.8 day orbit around around its M4-type host star (R*=0.304 +/- 0.012 R_odot, M*=0.296 +/- 0.026 M_odot, Teff = 3215+/-58K), part of the SPECULOOS TEMPOS program. We validate the planetary nature of TOI-6981 b using ground-based follow-up photometry, statistical validation and high-resolution spectroscopy. At such cold temperatures, TOI-6981 b sits roughly at the location…

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astro-ph.EPastro-ph.SR

The Occurrence Rate of Planets Around Subgiant Stars from TESS Photometric Survey

Arkaprova Dutta, Priyanka Chaturvedi

Subgiant stars represent a critical phase in stellar evolution, offering an opportunity to investigate how planetary systems respond to the early stages of post-main-sequence expansion. Despite their importance, systematic occurrence-rate studies of this population remain sparse compared with those of main-sequence and red-giant hosts. In this work, we present a uniform analysis of planet occurrence around a sample of 282,904 subgiant stars selected from the Gaia DR3 catalogue. We perform an ind…

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astro-ph.GA

Caught in the act: diffuse stellar and Ly$α$ emission around a halo-less quasar in the assembling cluster CARLA J0800+4029 at z=2

Sofia G. Gallego, Simona Mei, Emanuele Daddi, Gaël Noirot, Dominika Wylezalek, R. Michael Rich

Extended Ly$α$ emission is commonly detected around luminous quasars at $z\sim2$-3 and traces cold gas in the circumgalactic environment of the AGN. Together with the spatial distribution of galaxies, Ly$α$ probes gas and galaxy assembly in high-redshift overdensities. We use deep KCWI wide-field spectroscopy and HST/F140W imaging to investigate the assembling cluster CARLA J0800+4029 at $z=1.986\pm0.014$. No robust extended Ly$α$ emission is detected at the radio-loud quasar position. Instead,…

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astro-ph.HEhep-ph

Search for dark matter annihilation in the Sun using the full ANTARES dataset

A. Albert, S. Alves, M. André, M. Ardid, S. Ardid, J. -J. Aubert, J. Aublin, B. Baret et al.

Weakly Interacting Massive Particles (WIMPs) are among the most popular candidates for particle dark matter. In certain scenarios, WIMPs could be gravitationally captured into massive celestial objects and then annihilate into Standard Model particles, possibly leading to the emission of neutrinos. The ANTARES neutrino telescope, located in the Mediterranean Sea, is sensitive to neutrinos with energies ranging from a few tens of GeV to the TeV scale, making it well suited to search for the annih…

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gr-qcastro-ph.IM

Scaling RIFT 1: Extending RIFT to third-generation gravitational-wave analyses

R. O'Shaughnessy, A. Jan, J. Lange, R. Mechum

Interpretation of compact binary signals observed by third-generation gravitational-wave detectors is complicated by their high signal-to-noise ratios, often reaching hundreds to thousands, and by time- and frequency-dependent detector responses arising from Earth's rotation and the detectors' large physical extent. Building on prior work for LISA, we implement generic, robust extensions of the RIFT parameter estimation pipeline that enable interpretation of these sources using any existing wave…

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astro-ph.GA

The ALPINE-CRISTAL-JWST Survey: Investigating the role of interstellar dust, gas and stars in high-z galaxies at kpc-scales

F. Lopez, M. Relano, I. De Looze, A. L. Faisst, R. Herrera-Camus, R. A. Jorgenson, E. Pérez-Montero, M. Palla et al.

A comprehensive understanding of galaxy evolution requires a detailed analysis of gas and dust, their distribution, and evolution within galaxies. We analyse spatially resolved (~kpc) rest-frame [CII] and dust continuum ALMA observations together with JWST/NIRSpec IFU data of a sample of galaxies at z~4-5. We focus on deriving the spatial distributions of atomic and molecular gas masses, dust and stellar masses, star formation rates (SFR), and metallicity. The oxygen abundance maps have values i…

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astro-ph.SR

On the origin of carbon- and oxygen-rich hot subdwarfs: an sdB merger scenario

Bo Tang, Xinyu Ji, Songyu Hu, Zhongyang Liu, Xianfei Zhang

Carbon- and oxygen-rich hot subdwarfs (CO-sdO stars) represent an extremely rare subclass of helium-rich hot subdwarfs. Recent observations of PG 1654+322, PG 1528+025, and UCAC4 108 reveal unusually large surface mass fractions of carbon and oxygen, which are difficult to explain within existing formation scenarios. We explore whether mergers involving sdB stars can provide a viable formation channel for these objects. Using the stellar evolution code MESA, we model the post-merger evolution of…

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