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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.HE

SN 2025qe: A case study of diversity in low-luminosity thermonuclear explosions

Hrishav Das, Anirban Dutta, Devendra K. Sahu, G. C. Anupama, Prathamesh S. Kadam, Vishwajeet Swain

We present optical photometric and spectroscopic observations of SN 2025qe, a Type Iax supernova in IC 0529, monitored from $-10$ to $+150$ rest-frame days relative to $g'$-band maximum using the GROWTH-India and the Himalayan Chandra Telescopes. SN 2025qe reaches a peak $g'$-band absolute magnitude of $M_{g'} \approx -16.16 \pm 0.15$ mag, placing it in the sparsely sampled luminosity gap between the brightest and faintest members of the SNe Iax class. The multiband light curves show pronounced…

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astro-ph.HE

JWST unveils a dust-obscured supernova associated with a gamma-ray burst

B. Schneider, A. J. Levan, N. Sarin, N. A. Rakotondrainibe, B. P. Gompertz, V. Buat, J. T. Palmerio, D. B. Malesani et al.

Recent observations have challenged the duration-based classification of gamma-ray bursts (GRBs), making the detection of an associated supernova (SN) or kilonova crucial for conclusively identifying their progenitors. We investigate the origin of GRB 240825A at $z=0.659$, whose prompt emission gave conflicting indications of a merger or collapsar origin and for which no SN was detected in deep ground-based observations. We analyze JWST/NIRSpec observations obtained 66.5 days (40.1 days in the r…

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

K-dwarf starspot hunters: how to directly characterize spot and faculae properties with UV-IR panchromatic transit spectra

Joanna K. Barstow, Caitlyn Cullen, Yvonne Unruh, Hannah Wakeford, Eva-Maria Ahrer, Lili Alderson, Charlotte Fairman, Ulrich Kolb et al.

Transmission spectroscopy of exoplanets provides an important window into their atmospheric composition, structure and dynamics, especially in the JWST era. As the quality of the observational data and therefore the precision of our constraints improves, we become increasingly sensitive to sources of systematic bias in our models and observations. One significant example of this is the Transit Light Source Effect, in which heterogeneous features in the stellar photosphere - spots and faculae - i…

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

K-dwarf starspot hunters: how to directly characterize spot and faculae properties with UV-IR panchromatic transit spectra

Joanna K. Barstow, Caitlyn Cullen, Yvonne Unruh, Hannah Wakeford, Eva-Maria Ahrer, Lili Alderson, Charlotte Fairman, Ulrich Kolb et al.

Transmission spectroscopy of exoplanets provides an important window into their atmospheric composition, structure and dynamics, especially in the JWST era. As the quality of the observational data and therefore the precision of our constraints improves, we become increasingly sensitive to sources of systematic bias in our models and observations. One significant example of this is the Transit Light Source Effect, in which heterogeneous features in the stellar photosphere - spots and faculae - i…

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astro-ph.IMastro-ph.COphysics.comp-ph

Accelerating massive ensembles of ordinary differential equations

Lawrence Berry, Will Handley, Oliver Hahn, Nils Schöneberg

Solving large ensembles of small, independent ordinary differential equations (ODEs) is a common task in computational science and engineering, arising for example in Bayesian parameter estimation, Monte Carlo uncertainty quantification, and the integration of uncoupled physical systems such as the linearised Einstein-Boltzmann equations of cosmology. Modern graphics processing units (GPUs) with thousands of cores are well suited to such parallel workloads, but realising this potential requires…

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hep-phastro-ph.HE

The LZ event with a two-state dark matter halo

Vinicius Oliveira

The LUX-ZEPLIN (LZ) experiment has reported a single nuclear-recoil candidate at $E_R \simeq 248$keV. LZ interprets it in terms of inelastic dark matter that scatters endothermically from its ground state, $χ_1 N \to χ_2 N$. In pseudo-Dirac models the excited state $χ_2$ can survive to the present day, and exothermic scattering, $χ_2 N \to χ_1 N$, is then also open. The published LZ intervals do not describe this case. We rebuild the LZ statistical inference and validate it against the published…

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astro-ph.EP

JWST NIRSpec G395H Transmission Spectra of Two Similar Sub-Neptunes in the TOI-125 System

Yiwei Chai, Néstor Espinoza, Chloe Fisher, Erik Meier Valdes, Matthew Hooton, Brett Morris, Natalie H. Allen, Adam J. Burgasser et al.

The James Webb Space Telescope (JWST) has enabled the first in-depth characterisations of sub-Neptune atmospheres, revealing a diversity of chemical compositions and cloud properties that challenge current models. Multi-planet systems provide an opportunity to compare planetary atmospheres while controlling for formation conditions within the same protoplanetary disk. We present JWST NIRSpec G395H 3-5 um observations of two similarly-sized sub-Neptunes orbiting a sun-like star within the TOI-125…

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astro-ph.GA

GA-NIFS view of LAP1: Assembly of Pop~III stellar clusters during EoR

J. Scholtz, R. Maiolino, S. Carniani, E. Vanzella, R. J. Terlevich, H. Übler, M. Perna, S. Arribas et al.

Lensed and Pristine 1 (LAP1) is one of the most promising candidates for the detection of so-called Pop~III stars at $z\sim6.6$. In this work, we present new high-spectral-resolution ($R \sim 2700$) \jwst NIRSpec-IFS observations of the system along with a detailed re-analysis of all archival \jwst and VLT/MUSE data. We confirm the very low metallicity of the system, with $12+\log(\text{O/H})=6.5\text{--}6.8$ (1--2\% Z$_{\odot}$), and its low stellar mass, with $M_{*}= 10^{3\text{--}4}$ \Msun, b…

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gr-qcastro-ph.HEastro-ph.IM

Normalizing Flow Emulator for Gravitational Wave Detection Probability in the LIGO/Virgo/KAGRA O4 Observing Run

Julius Gassert, Ignacio Magaña Hernandez, Ariel J. Amsellem, Antonella Palmese, Barnabas Póczos

Efficient and accurate estimation of the detection probability of a gravitational wave event given its source parameters remains a challenging problem because it conventionally requires expensive Monte Carlo injection campaigns. We present a machine learning-based approach using Normalizing Flows (NFs) to estimate the detection probability of gravitational wave events for a LIGO/Virgo/KAGRA O4-like detector network configuration. We utilize the publicly available injection dataset as training an…

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astro-ph.GAastro-ph.CO

The abundance and emission of PAHs from the local to early Universe

Massimiliano Parente, Desika Narayanan, Paul Torrey, Gian Luigi Granato, Brandon S. Hensley, Jed McKinney, Alexandra Pope, Gergö Popping et al.

We present the first large-volume cosmological simulation of galaxy evolution with a model for the abundance and luminous emission of Polycyclic Aromatic Hydrocarbons (PAHs) across a wide range of cosmic time ($0 < z \lesssim 6$). The simulation is built on a semi-analytic model (SAM) that includes a treatment of dust size distribution, with PAHs being identified with the smallest carbonaceous grains ($< 15$ A) residing in the diffuse ISM of galaxies. PAH emission is computed by post-processing…

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astro-ph.GA

Precise C-N-O Abundances of Individual Galaxies in the First Billion Years from Ultra-Deep, Rest-UV-to-Optical JWST Spectroscopy

Raunaq Singh Rai, Guido Roberts-Borsani, Ryan Sanders, Alice E. Shapley, Leonardo Clarke, Pascal A. Oesch, Daniel Schaerer, Rui Marques-Chaves et al.

We present ultra-deep JWST/NIRSpec $R\sim1000$ spectroscopy of nine star-forming galaxies at $z=6.0-8.3$ in the GOODS-N field, drawn from the Origins of Metal Enrichment in Galaxies at cosmic dAwn (OMEGA) survey. Paired with ancillary ultra-deep G140M observations, the G395M integrations from OMEGA yield continuous rest-frame UV-to-optical coverage and the full suite of diagnostics needed for precise characterisations and measures of the chemical abundances of these systems. Crucially, the auror…

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astro-ph.GAastro-ph.CO

Massive Population III Galaxies Near a GN-z11 Analog: The Role of the Baryon-Dark Matter Streaming Velocity

Eli Visbal, Greg L. Bryan, Ryan Hazlett

Recently the James Webb Space Telescope (JWST) detected Hebe, a Population III (Pop III) candidate located ${\sim}3$ kpc in projection from the massive $z=10.6$ galaxy GN-z11. This raises the question of whether Pop III star formation is expected in the vicinity of massive high-redshift galaxies or whether it would be prevented by early metal enrichment. We address this with a semi-analytic model of Pop III and metal-enriched star formation applied to a zoom-in N-body simulation of a highly over…

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astro-ph.IM

Refactoring the SIXTE simulator: Towards a more modular code base

Christian Kirsch, Maximilian Lorenz, Lea Dauner, Esin G. Gülbahar, Karan Pal, Neo Reinmann, Jakob Stierhof, Philipp Thalhammer et al.

The SIXTE (SImulation of X-ray TElescopes) software is a general end-to-end simulation toolkit for X-ray observations, covering the full observation process from source photon generation to detector readout and the production of high-level output files. It is the official simulator for existing and future X-ray missions, such as \textit{eROSITA}, \textit{NewAthena}, \textit{THESEUS} and \textit{AXIS}. Originally being designed as a simulator for \textit{eROSITA}, the addition of new instrument a…

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astro-ph.IM

Refactoring the SIXTE simulator: Towards a more modular code base

Christian Kirsch, Maximilian Lorenz, Lea Dauner, Esin G. Gülbahar, Karan Pal, Neo Reinmann, Jakob Stierhof, Philipp Thalhammer et al.

The SIXTE (SImulation of X-ray TElescopes) software is a general end-to-end simulation toolkit for X-ray observations, covering the full observation process from source photon generation to detector readout and the production of high-level output files. It is the official simulator for existing and future X-ray missions, such as eROSITA, NewAthena, THESEUS and AXIS. Originally being designed as a simulator for eROSITA, the addition of new instrument and telescope types over several years has mad…

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astro-ph.GA

Diverse Metallicities in Protoclusters at $z \sim 3.4$ detected by Deep Learning

Yoshihiro Takeda, Nobunari Kashikawa, Kei Ito, Jun Toshikawa, Mariko Kubo, Rieko Momose, Yongming Liang, Takehiro Yoshioka et al.

We present spectroscopic follow-up observations with Subaru/MOIRCS of four protocluster candidate regions identified by the deep-learning model PCFNet. In three candidate regions, we confirm four protoclusters at $z =$ 3.316, 3.403, 3.408 and 3.425, exhibiting galaxy density peaks over five times the uniform distribution. The detection rate of confirmed members aligns with PCFNet's predictions, underscoring its effectiveness. Analysis of spectral energy distributions (SEDs), incorporating up to…

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astro-ph.IMastro-ph.COastro-ph.GA

Source--Line Associations in JWST/NIRSpec Dense-Shutter Spectroscopy

Zihao Wu, Daniel J. Eisenstein, Francesco D'Eugenio, Erica Nelson, Benjamin D. Johnson, Andrew J. Bunker, Zhiyuan Ji, Pierluigi Rinaldi et al.

We demonstrate the feasibility of source--line association in JWST/NIRSpec dense-shutter spectroscopy, with $\sim$2000 sources observed simultaneously per pointing regardless of spectral overlap. While JWST wide-field slitless spectroscopy (WFSS) can disentangle overlapping spectra using two grisms with perpendicular dispersion directions, NIRSpec can achieve this using gratings with different dispersions. Compared with WFSS, NIRSpec dense-shutter spectroscopy offers substantially higher sensiti…

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astro-ph.SR

V405 Draconis: A Deep Contact Binary with a Tertiary Companion and a Quadruple System Candidate

Maksym Yu. Pyatnytskyy, Ivan L. Andronov

We continued our analysis of the O-C diagram of the EW-type eclipsing binary V405 Dra using recently available data. We refined the orbital parameters of the third body responsible for the short-period oscillations in the O-C curve, obtaining $P_3=513.12(20)$ d, $a_{12}\sin i_3=0.3862(15)$ AU, and $e_3=0.1690(48)$. Assuming a total mass of $1.56$ $M_\odot$ for the eclipsing binary, the minimum mass of the third body is estimated to be about $0.5$ $M_\odot$. We also investigated the complex long-…

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astro-ph.IM

Diffusion Models for Polarimetric Reconstruction of Circumstellar Environments in Correlated Speckle Noise

Quentin Villegas, Laurence Denneulin, Simon Prunet, André Ferrari, Éric Thiébaut, Maud Langlois

High-contrast polarimetric imaging of circumstellar disks is severely limited by stellar leakage and speckle noise. Building upon the RHAPSODIE framework for polarimetric inverse problems, diffusion-based methods have shown promising results by replacing classical regularization with learned priors. However, RHAPSODIE's white noise assumption fails to capture the spatial correlation structure of atmospheric and instrumental speckles. We extend this framework to handle speckle fluctuations, which…

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astro-ph.GA

Extreme MgII Emission in Recently-Quenched Galaxies: A New Sample of Intermediate-Redshift Post-Starburst Quasars from the DESI Early Data Release

Margaret E. Verrico, Aayan Verma, K. Decker French, David J. Setton, Omar Almaini, Jenny E. Greene, Stephanie LaMassa, Yuanze Luo et al.

Post-starburst galaxies are galaxies which have recently and rapidly shut off star formation. AGN activity is often invoked to explain this rapid quenching, but most post-starburst selection methods select against optical AGN, motivating searches for "post-starburst quasars." We present DESI observations of ten post-starburst quasars with significant MgII emission ($L_{\text{MgII}} \geq 3 \times 10^{41}$ erg/s). This is the first sample of post-starburst quasars to be selected from a post-starbu…

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astro-ph.GAastro-ph.CO

ViCTORIA project: A pilot study of the M49 region in the Virgo cluster in polarisation

A. Spasic, A. Benati, M. Brüggen, H. W. Edler, F. De Gasperin, V. Gustafsson, P. Serra, A. Bonafede et al.

Large-scale magnetic fields permeate the Intracluster Medium (ICM) of galaxy clusters. Understanding these fields gives an insight into the origin of cosmic magnetic fields and the interaction of cluster galaxies with the ICM. Using MeerKAT observations of the Virgo cluster as part of the ViCTORIA project, we probe magnetic fields via Rotation Measure (RM) synthesis. The aim of this work is to characterise the magnetic fields in and around the infalling group M49 in the Virgo cluster. We will pr…

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astro-ph.GAastro-ph.IM

The 2MIG isolated AGNs -- 4. Linking hot-dust reverberation to spectroscopically predicted BLR scales in IC~5287 and Mrk~845

I. O. Izviekova, I. B. Vavilova, O. V. Kompaniiets, O. Zamora, R. Clavero

We investigate the relation between directly measured hot-dust reverberation scales and spectroscopically predicted broad-line region (BLR) scales in the isolated Seyfert galaxies IC~5287 and Mrk~845 (MCG+09-25-022), combining ZTF optical light curves, WISE/NEOWISE monitoring, and archival SDSS spectroscopy. Both nuclei show BWB optical variability, RWB MIR behaviour, and delayed MIR responses consistent with circumnuclear dust reprocessing. For IC~5287, interpolated cross-correlation function a…

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astro-ph.GA

Probing Spatial Variations in IGM Transmission: Higher Ly$α$ Visibility in an H$α$-Selected Galaxy Overdensity at $z\simeq6.2$

Shunta Shimizu, Nobunari Kashikawa, Junya Arita, Ryo Emori, Kohei Inayoshi, Akio K. Inoue, Kei Ito, Satoshi Kikuta et al.

The visibility of Ly$α$ emission during the epoch of reionization depends on both galaxy properties and the transmission of Ly$α$ photons through the intergalactic medium (IGM). Using JWST/NIRCam F470N imaging, we identify a prominent projected overdensity of H$α$ emitters (HAEs) at $z\simeq6.2$ in CEERS field. We use Subaru/HSC NB872 imaging to measure their Ly$α$ fluxes and compare the Ly$α$ visibility of galaxies within $2'$ of the density center with that of galaxies outside this region. The…

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astro-ph.IM

Stellar interferometry with a K-band integrated optics beam combiner instrument at the CHARA Array - I. First on-sky fringes for CHARIOT

Aline N. Dinkelaker, Kévin Barjot, Nic Scott, Aurélien Benoît, Narsireddy Anugu, Alyssa V. Mayer, Jacopo Siliprandi, Robert R. Thomson et al.

We present the instrument description and the first on-sky observations for the new CHara ARray Integrated Optics Testbench (CHARIOT) at the CHARA Array. CHARIOT is a 2-telescope proof-of-concept instrument that utilises a fibre-connectorised beam combiner fabricated by ultrafast laser-inscription in Infrasil quartz glass, which presents low-OH contamination and high transparency over the whole K-band. With its fibre-connected architecture, CHARIOT is designed as a plug-and-play testbed instrume…

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astro-ph.GAcond-mat.mtrl-sci

Photoelectron and electron microscopy investigation of laboratory grown Mg-silicate space dust analogues

Steffen Friis Holleufer, Mie Andersen, Frederik Granzow Doktor, Lars Eric Borchert, Martin Wibrand Larsen, Duncan S. Sutherland, Zheshen Li, Alexei Preobrajenski et al.

The atomic structure at the surface of interstellar silicate dust particles likely plays a key role in a variety of chemical processes occurring in star- and planet-forming regions of the interstellar medium (ISM). Here, we use the photoelectric effect to characterize, in situ, the local chemical structure of Mg-silicate nanoparticulate films, and ex situ electron microscopy to trace changes to morphology resulting from different starting compositions. Nanoparticulate films are prepared via co-d…

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astro-ph.SR

A First Global Full-Vector Coronal Magnetic Field Inference Using MLSO CoMP and UCoMP Observations

Alin Razvan Paraschiv, Zihao Yang, Daniela Adriana Lacatus, Momchil Molnar

Building on recent advances in coronal spectropolarimetry, seismology, and magnetic-field inferences of Z. Yang et al. (2024) and A. R. Paraschiv (2026), we present the first application of the CLEDB IQUD inversion methodology to Mauna Loa Solar Observatory CoMP and UCoMP observations. Using spectropolarimetric IQU measurements together with coronal seismology derived magnetic field BPOS constraints, we recover vector magnetic field solutions across the off-limb solar corona accessible to the ob…

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physics.space-phastro-ph.EPastro-ph.SRphysics.comp-phphysics.plasm-ph

Spectral Properties of Solar Wind Charge Exchange from Earth's Magnetospheric Boundaries: MHD and Test Particle Simulations

A. Ramachandran, R. T. Desai, H. L. Norman, Y. Tong, D. Bewicke, S. Nitti, J. A. Carter, J. P. Eastwood et al.

The Solar Wind Charge Exchange (SWCX) mechanism, where X-rays can be generated through interactions between heavy, highly charged solar wind ions and neutral atoms, offers an opportunity to observe the large-scale transfers of energy and momentum through the Sun-Earth system. In this study, we simulate SWCX signatures from Earth's outer boundaries using Gorgon global magnetohydrodynamic (MHD) simulations combined with kinetic particle-based simulations which we call the X-ray Imaging of the Magn…

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astro-ph.HE

Investigating signatures of extinct PeVatron activity in supernova remnants IC 443 and W51 C

Silvia Celli, Giovanni Morlino

Context. Supernova remnants (SNRs) are renewed sources of non-thermal particles and the main contributors of Galactic cosmic rays (CRs). Recent ultra-high energy (UHE) gamma-ray data from middle-aged SNRs, such as IC 443 and W51 C, highlight the key role of these systems for particle acceleration. Understanding SNR contribution to PeV CRs requires a detailed modelling about how accelerated particles escape their shocks and are released inside the Galaxy. Aims. We aim at critically assessing the…

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astro-ph.IM

I2C@2024: an interferometric imaging contest in 2024

Florentin Millour, Mathis Houll{é}, Jeremy Perdigon, Julien Drevon, Ryan Norris, Rebecca Proni, Alexis Matter, Ferreol Soulez et al.

Images in optical long-baseline interferometry have seen a boost in the recent years thanks to new techniques and recipes invented by the community. These images are more and more used for science interpretation and not only illustration, and their fidelity has improved significantly, thanks mainly to the increase in the number of telescopes used in interferometers. The focus today is to improve their reliability and dynamic range. With this contest, we follow up the quest introduced in 2004 of…

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

MATISSE in the era of GRAVITY+

Florentin Millour, Anthony Soulain, St{é}phane Lagarde, Alexis Matter, Valentin Fleury, Farin Drewes, Mathis Houll{é}, Jules Scigliuto et al.

MATISSE, the mid-infrared spectro-interferometric imager of the Very Large Telescope Interferometer (VLTI), has been feeding on the light corrected by the GRAVITY+ Adaptive Optics (GPAO) systems since the retirement of MACAO on the four Unit Telescopes in 2024. We report the assessment of the new MATISSE performance with GPAO, based on commissioning observations obtained in 2024 and 2025 and compared with archival MACAO observations of the same stellar sources. The instrumental visibility transf…

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astro-ph.IM

The best of all worlds: gravitational-wave transient detection with multiple pipelines

Nikolas Moustakidis, Theofilos Moustakidis, Deep Chatterjee, Anastasios Tefas, Erik Katsavounidis

The search for gravitational-wave transients (modeled and unmodeled) as performed by the LIGO-Virgo-KAGRA collaborations and the broader community typically involves multiple detection algorithms, often redundant and sometimes complementary. We here address the problem of combining such detection algorithms in order to maximize the noise vs signal discrimination power of such an astrophysical search that utilizes multiple analysis pipelines. Using a machine learning approach, we construct a neur…

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