UchUchU

Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.IM

Optimization of adaptive optics correction during observations: Algorithms and system parameters identification in closed-loop

Clémentine Béchet, Michel Tallon, Éric Thiébaut

The adaptive optics (AO) on the European Extremely Large Telescope, as well as earlier pathfinders like the Adaptive Optics Facility, at the Very Large Telescope in 2014, will no longer be stationary systems. AO is no longer isolated on a bench; some elements are directly in the optical train of the telescope, suffering environment and constrains changes during the observations. To guarantee good performance at any observing time, we investigate a self-calibration strategy. We focus here on one…

Read →
astro-ph.IMastro-ph.CO

BICEP/Keck XXII: Analysis of the South Pole Atmosphere for CMB Observations

P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, D. Barron, R. Basu Thakur, I. Birdwell, C. A. Bischoff et al.

The South Pole is among the driest sites on Earth, and the resulting high atmospheric transparency makes it an excellent site for millimeter-wave astronomical observations. Nevertheless, for bolometric surveys of the cosmic microwave background (CMB), fluctuations in line-of-sight water vapor drive variable atmospheric emission, which has a significant impact on survey sensitivity. We have deployed a water vapor radiometer (WVR) to characterize these fluctuations in space and time and to compare…

Read →
astro-ph.IM

Lightweight Soft X-ray Imager (LSXI) with glass-based coded mask

Dali Zhang, Chao Zheng, Lu Wang, Haopeng Li, Jinpeng Zhang, Xinqiao Li, Shaolin Xiong, Longhui Li et al.

The coded mask technique has been widely used in X-ray and Gamma-ray imagers, especially in space astronomy. However, the traditional design of coded mask imagers usually has problems with large size and heavy weight. Here, we propose a novel design for a coded mask imager made of glass based on microchannel plate (MCP) technology, making it lightweight (within 1 kg), compact, and self-supporting, which is very suitable for space exploration satellites. The design is initially demonstrated by re…

Read →
astro-ph.HE

Are Repeaters Prevalent Among the Known Fast Radio Burst Sources?

Xiao-Fei Dong, Qing Pan, Yong-Feng Huang, Zhi-Bin Zhang, Hao-Xuan Gao, Jin-Jun Geng, Xue-Feng Wu, Lang Cui et al.

Fast radio bursts (FRBs) are millisecond radio pulses of unknown origin. Despite extensive follow-up observations, only $\sim3\%$ of FRBs have been confirmed as repeaters. It remains unclear whether the rest are truly one-off bursts, or essentially repeating sources that have only been detected once due to limited monitoring time. Using the second CHIME/FRB catalog, we test this debate by comparing non-repeaters with two repeater-based subsamples: the first-detected bursts of repeaters and their…

Read →
astro-ph.IM

A measurement-based approach to EPFD calculation, to quantify the impact of satellite mega-constellations on low-frequency radio astronomy

Steven J. Tingay, Gregory Hellbourg, Daniel Sheen, Dylan Grigg, Benjamin Winkel, Federico Di Vruno, Balthasar Indermuehle

Context: Satellite mega-constellations generate Unintended Electro-Magnetic Radiation (UEMR) impacting low frequency radio astronomy. The Radio Regulations of the International Telecommunications Union Radiocommunication Sector (ITU-R) contain the basis for addressing UEMR, but enforcement mechanisms are absent. Aims: To adapt compatibility study methods based on satellite constellation simulations, in particular the Equivalent Power Flux-Density (EPFD) framework, to radio telescope measurements…

Read →
astro-ph.IMphysics.optics

Scalability in Simulating a Large-Aperture, Fresnel Zone Plate Lens for a Conceptual Space Telescope

Maneesha Dushmantha De Zoysa, Yangwoo Seong, Ho Xuan Vinh, Jae Hung Han, Hyun Jung Kim

As ambitious space telescope concepts such as ultra-lightweight planar diffractive optical elements (DOEs) emerge, validating the performance remains a major computational challenge. Conventional Fourier propagation algorithms were observed to fail at meter-class apertures due to severe memory limits caused by rigid grid-sampling requirements, and the scaled-down proxy models used for reflector telescopes cannot be applied, since scaling compresses the outermost zones that govern resolution. We…

Read →
astro-ph.IM

The Impact of Artificial Space Objects on Optical Astronomy as Determined from 32 Million Photometric Observations

Anthony Mallama, Sergey Karpov, Richard E. Cole

Photometric observations of satellites, rockets and space debris brighter than magnitudes 6.0, 7.0 and 8.0 are characterized. Those magnitudes pertain to different levels of interference with astronomy as defined by the International Astronomical Union. The densities of objects per square degree of sky and brighter than the magnitudes listed above are 0.38 e-3, 0.76 e-3 and 1.10 e-3, respectively. Probabilities of objects appearing on astronomical images depend on the field of view and the expos…

Read →
astro-ph.GA

The GOGREEN Survey: AI Powered Deconvolution Lifts The Veil on Outside-in Environmental Quenching at z > 1

Aurelien Henry, Gillian Wilson, Gregory Rudnick, Pascale Jablonka, Utsav Akhaury, Craig Brooks, Michael Balogh, Ben Forrest et al.

A powerful probe of the physical processes that quench star formation in dense environments is determining where within galaxies star formation is suppressed. At high redshift, the spatial resolution of multi-band imaging limits such measurements. We use deep-learning-based deconvolution to recover spatially resolved optical and near-infrared photometry for galaxies in nine GOGREEN clusters at 1<z<1.4, using customized models trained on HST and JWST imaging. Using resolved rest-frame UVJ colors,…

Read →
astro-ph.IM

Curving X-ray detectors for astrophysics applications

Eric D. Miller, James A. Gregory, Keith Warner, Beverly LaMarr, Gregory Prigozhin, Marshall W. Bautz, Harry R. Clark, Michael J. Cooper et al.

Next-generation X-ray optics will revolutionize high-energy astrophysics, yet they present several challenges to design a complementary focal plane. In particular, the focal surface is curved, requiring many small, flat sensors to achieve a large field. We present work building on MIT Lincoln Laboratory technology to curve the sensor itself, improving image quality and reducing complexity. Applying this technology to back-illuminated, large-format CCDs having well-characterized X-ray response, w…

Read →
astro-ph.IMastro-ph.GA

The ViSta method for optimized stacking of broadband interferometric data in the Fourier domain

Martina Torsello, Marcella Massardi, Elisabetta Liuzzo, Gayathri Gururajan, Francesca Perrotta, Andrea Lapi

We present the optimized version of ViSta, a visibility-domain stacking method that combines interferometric observations in the Fourier domain from radio to sub-millimeter wavelengths. By stacking visibilities directly and transforming them into the rest frame, ViSta enhances the signal, suppresses noise, and improves image reconstruction through extended uv-coverage. ViSta outperforms image stacking when individual sources are too faint to detect, achieving higher SNR in the low-signal and ext…

Read →
astro-ph.GAastro-ph.SR

EWOCS-IX: JWST/NIRCam observations of Westerlund 2 - Identification of candidate substellar members

V. Almendros-Abad, M. G. Guarcello, K. Muzic, A. Scholz, M. Andersen, A. Bayo, W. Best, D. Capela et al.

[Abridged] Investigating substellar populations in young massive clusters offers crucial insights into the formation of brown dwarfs (BDs) and the role of environmental conditions in shaping their properties. Westerlund 2 (Wd2), as one of the nearest dense and massive clusters in the Milky Way, represents an ideal laboratory for studying the effects of high stellar density and ionizing radiation from massive stars on BD formation. This paper presents deep JWST/NIRCam observations of Wd2 in a lar…

Read →
astro-ph.COastro-ph.IM

Blast.jl: Differentiable Non-Limber Power Spectra for Joint Clustering, Shear, and CMB lensing Analyses

Sofia Chiarenza, Marco Bonici, Stefano Camera, Giulio Fabbian, Carlos García-García, Alex Krolewski, Will J. Percival

Upcoming large-scale structure surveys require accurate theoretical predictions for angular power spectra on the largest angular scales, where the commonly used Limber approximation breaks down and multiple relativistic and observational effects become relevant. At the same time, modern cosmological analyses increasingly rely on gradient-based inference techniques, motivating the development of fast, fully differentiable algorithms. In this work, we present a major extension of Blast.jl, a numer…

Read →
astro-ph.SRastro-ph.EPastro-ph.GA

Mass-dependent multiplicity fraction in low mass stars revealed by Gaia astrometry

Ben Pennell, Hans-Walter Rix, Kareem El-Badry, Sahar Shahaf, Johanna Müller-Horn, Jiadong Li

Stellar multiplicity at different orbital periods is probed by different techniques: radial velocities at the shortest periods, direct imaging at the longest, and astrometry in between. Gaia DR3 provides unprecedented astrometric information to constrain binary populations with periods of tens to thousands of days. Beyond the small fraction of direct orbit solutions, Gaia publishes coarser astrometric diagnostics for all objects, such as on-sky accelerations, jerks, or the single-star goodness-o…

Read →
astro-ph.SR

Chemical evolution of Na, Mg, and Al in the Galactic bulge from UVES data

R. P. Nunes, B. Barbuy, C. Chiappini, A. Friaça, M. C. Jelin, V. Hill, M. Zoccali, A. Renzini et al.

The formation of the Galactic bulge remains incompletely understood, with evidence pointing to different stellar populations, including a bar-driven component, an inner-disk population, and an older spheroidal component. Chemical abundances provide critical constraints on the origin of these populations, particularly for odd-Z elements such as Na and Al, as well as Mg, whose behaviour at high metallicity is still a matter of debate. We aim to investigate the presence of overabundances of Na, Mg,…

Read →
astro-ph.GAastro-ph.CO

Dark Matter Halo Tumbling Induced by Torques from Massive Mergers

Neil Ash, Monica Valluri

Dark Matter halos exhibit slow tumbling known as `figure rotation'. Figure rotation occurs in roughly $80\%$ of isolated $Λ$CDM halos and is relatively unaffected by baryonic feedback, making it an attractive and relatively unexplored test for $Λ$CDM. However, galaxy mergers are capable of exerting strong torques on a host halo's quadrupole, warranting an investigation of whether such interactions are capable of influencing figure rotation. Using isolated $N-$body simulations and 6 TNG50 halos c…

Read →
astro-ph.EPastro-ph.SR

Precise Stellar Age Constraints and Habitable Zone Evolution in Exoplanet Systems

Grace Henry, Ted von Hippel, Anna Childs

Accurate stellar ages are fundamental to interpreting the evolutionary histories of habitable zone (HZ) planets. Because stellar luminosity evolves over time, HZ boundaries migrate outward, meaning that present-day HZ planets may have experienced different irradiation environments earlier in their evolution. Accurate ages are therefore required to estimate HZ residence times and place planetary habitability in an evolutionary context. We use the Bayesian Analysis of Stellar Evolution with nine p…

Read →
astro-ph.EPastro-ph.GA

IFU Observations of Comet 3I/ATLAS = C/2025 N1 (ATLAS) using the Hobby-Eberly Telescope with the VIRUS Instrument

Anita Cochran, Gregory Zeimann, Emmanuel Jehin, Hideyo Kawakita, Adam McKay

We observed interstellar object 3I/ATLAS = C/2025 N1 (ATLAS) on 9 December 2025 UT with the VIRUS spectrograph on the Hobby-Eberly Telescope. VIRUS is a low spectral resolving power, multi-IFU, optical spectrograph. We used a single IFU for the observations and were able to obtain spectra spaced every one arcsec (1327 km) from the optocenter out to about 85,000 km in the sunward direction. The spectra include molecular features normally seen in the optical for spectra of Solar System comets, wit…

Read →
astro-ph.HEastro-ph.SR

The Mass-Ratio Distribution of the Low-Mass Binary Black Hole Subpopulation: A Natural Outcome of Isolated Binary Evolution

Monica Gallegos-Garcia, Anarya Ray, Vicky Kalogera, Max Briel, Michael Zevin, Abhishek Chattaraj, Zepei Xing, Jeff J. Andrews et al.

The observed merging binary black hole population is increasingly consistent with being composed of a mixture of subpopulations, each likely the result of different formation mechanisms. In particular, the low-mass subpopulation, with primary black hole masses below $\approxeq 15\,M_{\odot}$, has been attributed to mergers formed through isolated binary evolution. We use the binary population synthesis code POSYDON to study the mass ratio $(q)$ distribution of binary black hole mergers from isol…

Read →
astro-ph.GAastro-ph.IM

Virgo Filaments VIII: Characterizing the Structural Parameters of Virgo Galaxies with Machine Learning to Probe Environmental Quenching

Kim Conger, Gregory Rudnick, Rose A. Finn, Rebecca A. Koopmann, Benedetta Vulcani, Dennis Zaritsky, Gianluca Castignani, Francoise Combes et al.

A persistent challenge in galaxy evolution involves disentangling the many correlated properties in order to isolate the effects of a galaxy's environment on its star formation history. To address this multidimensionality problem, we apply k-means clustering to 2831 galaxies in the extended regions around the Virgo cluster to define objective, reproducible subsets of structurally similar galaxies. Using measurements of size, light distribution, and stellar mass, k-means partitions these galaxies…

Read →
astro-ph.IMnlin.CD

Learning and Predicting the Nonlinear Variability of X-ray Binaries with the Koopman Operator

Eric Miao, Ruo-Yu Shang, Kaya Mori, Reshmi Mukherjee

X-ray variability in compact-object binaries encodes the nonlinear dynamics of corona-jet interactions and accretion disk instabilities. Standard timing techniques characterize periodic and quasi-periodic variability well, but do not model underlying nonlinear dynamics or forecast their evolution. We apply Koopman operator theory and a data-driven approximation, extended dynamic mode decomposition (EDMD), to X-ray light curves for the first time. Koopman theory represents nonlinear evolution as…

Read →
astro-ph.EP

From orbit to ground: pre-impact meteorite strewn field predictions for imminent impactors and meteorite recovery

Anna Moscati, Marco Fenucci, Laura Faggioli, Marco Micheli, Francisco Ocaña, Juan Luis Cano

The flux of meteoroids reaching the Earth is continuous, ranging from microscopic grains to occasional metre and decametre scale bodies. The smallest ones fully ablate in the upper atmosphere, whereas sufficiently large or strong objects survive entry and deposit fragments on the ground as meteorites. Predicting where these fragments land, and reconstructing the atmospheric trajectory and fragmentation sequence that produced them, is central both to hazard assessment and to the recovery of fresh…

Read →
astro-ph.EP

Mass constraints for the K2-223 system planets: An ultra-short-period sub-Earth, a short-period super-Earth, and a tentative long-period giant planet

Dawid Jankowski, Grzegorz Nowak, Gaia Lacedelli, Enric Pallé, Krzysztof Goździewski, Thomas Masseron, Ilaria Carleo, Rafael Luque et al.

We present mass constraints of two short-period, terrestrial-sized planets transiting K2-223, based on high-precision radial velocity measurements from HARPS-N and ESPRESSO, as well as a tentative indication of an outer, Jupiter-like planet orbiting the G1V dwarf K2-223. With a radius of $R_\mathrm{b}=0.79\pm0.10$ $\mathrm{R_{\oplus}}$ and 3-$σ$ upper mass limit $M_\mathrm{b}<2.8$ $\mathrm{M_{\oplus}}$, K2-223 b belongs to the small group of known sub-Earth planets and is currently the smallest…

Read →
hep-phastro-ph.HEhep-ex

SN1987A constraints on the neutrino-dark-fermion interaction from resonant scattering with C$ν$B

Christina Gao, Ke Hu, Kun-Feng Lyu, Vincent Zou

Neutrino self-interactions mediated by a light scalar offer a compelling resolution to cosmological tensions and may naturally arise in neutrino mass generation mechanisms. When the scalar also couples to a light dark-sector fermion, supernova neutrinos can resonantly annihilate with the cosmic neutrino background (C$ν$B) into invisible dark radiation, depleting the flux en route to Earth. We use this depletion to constrain the neutrino-scalar coupling from the SN1987A data. Within a Bayesian fr…

Read →
astro-ph.HE

Measuring Small-scale Turbulence in Supernova Remnants with Jitter Radiation

Emily Simon, Damiano Caprioli, Niccolò Bucciantini, Emanuele Greco, Marco Miceli

Hard X-ray emission from Cas A has been attributed to jitter radiation, implying magnetic turbulence on scales near or below the ion Larmor radius. We propose these fields arise from ion-scale micro-instabilities (e.g., mirror and firehose) in the shock downstream, and use high-resolution hybrid simulations to demonstrate the generation of such small-scale turbulence. Its spectral index, once numerical dissipation is accounted for, is consistent with that inferred for Cas A, suggesting that jitt…

Read →
astro-ph.GAastro-ph.CO

JWST Reveals a Candidate Supermassive Black Hole Binary at z=4.3 in the Brightest Sub-millimeter Galaxy in COSMOS-Web

Jed McKinney, Ansh Gupta, Julian B. Munoz, John Chisholm, Caitlin M. Casey, Stephanie M. Urbano Stawinski, Olivia Cooper, Erini Lambrides et al.

We present JWST/NIRSpec PRISM and G395M grating spectroscopy for AzTEC-1, a massive sub-mm bright galaxy at $z=4.34$ in the COSMOS extragalactic field. The PRISM spectrum reveals strong H$α$, a significant Balmer break, and no H$β$ detection, indicating a $100-400$ Myr-old stellar population and high dust attenuation. BPT line ratios indicate the presence of an Active Galactic Nucleus (AGN). Decomposing narrow and broad line components, we recover broad, blueshifted H$α$ with a velocity offset o…

Read →
astro-ph.GA

The Comprehensive Investigations of the NGC 7419 Open Cluster and the New Perspective on Mass Populations

Nasser M. Ahmed, Remziye Canbay, Deniz Cennet Çınar

We present a structural, kinematic, and photometric analysis of the young, red supergiant- and Be star-rich open cluster NGC 7419 using Gaia DR3 and 2MASS data. Using the HDBSCAN algorithm and conservative membership criteria, we identify 734 high-probability cluster members, separating the cluster from the dense Perseus Arm background. Isochrone fitting to the Gaia DR3 color-magnitude diagram, treating classical Be stars separately to account for their circumstellar excess, yields an age of 15…

Read →
astro-ph.GA

Linking neutral gas inflows and outflows to offsets in the star-forming main sequence and mass-metallicity relation

S. Weng, M. Pieri, A. Saintonge, D. Scholte, D. Muñoz Santos, T. Hu, J. Aguilar, S. Ahlen et al.

Gas inflows and outflows regulate galaxy growth, but direct observational links between measured gas flows and galaxy scaling relations remain limited. Using ~6,000 star-forming galaxies with down-the-barrel Na I D absorption from DESI DR2, we examine how systems with detected neutral-gas inflows and outflows populate the star-forming main sequence (SFMS) and mass-metallicity relation (MZR). Inflow and outflow hosts are compared with stellar-mass- and redshift-matched controls, and with SFMS and…

Read →
cs.LGastro-ph.IMphysics.plasm-ph

Generative Diffusion Surrogates with Analytical Variance Schedule

Patrick Reichherzer, Gianluca Gregori, David N. Hosking, Subir Sarkar

Stochastic transport describes physical systems in which an initially structured distribution spreads under unresolved forcing, scattering, or heterogeneous media. Useful surrogates for such systems should be probabilistic, time-resolved, and able to represent non-Gaussian distributional structure. Generative diffusion models, which corrupt data with Gaussian noise and learn a reverse flow back to structured states, have these properties. Their noise schedules, however, are usually chosen heuris…

Read →
astro-ph.GAastro-ph.IM

The HERON Coma Project: Exploring the low-surface-brightness frontiers in the Coma cluster

Javier Román, R. Michael Rich, Pablo M. Sánchez-Alarcón, Yolanda Jiménez-Teja, Chester Li, Mónica Esquide

The technical complexity of data processing and residual instrumental systematics remain among the main barriers to reaching the faintest low-surface-brightness (LSB) regimes in the local Universe. Here, we present the HERON Coma Project, a deep $g$- and $r$-band imaging campaign on the Coma cluster carried out with the LSB-optimized 71-cm Jeanne Rich Telescope. The observing and processing strategy combines accurate flat-fielding, sky-background modeling and extended point spread function (PSF)…

Read →
astro-ph.EP

Constraining the Planetary Obliquity Distribution of Warm Jupiters

Caleb Lammers, Joshua N. Winn

Warm Jupiters are an intriguing class of planets with uncertain origins. Their planetary obliquities could help distinguish between different formation pathways: planet-planet scattering and migration across resonances can excite large obliquities, whereas in-situ formation would more naturally produce low obliquities. We searched for oblateness-related anomalies in the transit light curves of six observationally favorable warm Jupiters: TOI-201b, TOI-1670c, TOI-199b, Kepler-9c, Kepler-30c, and…

Read →