UchUchU

Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GA

Probing the Orientation Distribution of Nearby Double White Dwarfs through Gravitational Waves with LISA

N. Seto, G. C. Liu

We present a framework to study the orientation distribution of nearby double white dwarf binaries with LISA, explicitly accounting for the fourfold degeneracy in the polarization angle. Exploiting the belt-like sky distribution of the nearby sample along the Galactic plane, we show that the low-multipole extraction can be recast as an effectively one-dimensional Fourier analysis along Galactic longitude, within a spherical-harmonic expansion based on the Wigner-\(D\) formalism. The symmetry wit…

Read →
astro-ph.IM

Linear motion (R-FLEX) for minature 6.2 mm pitch optical fiber position robots with polar (R-theta) kinematics

Nicholas R. Wenner, Joseph H. Silber, Michael S. Schubnell, David J. Schlegel, Robert W. Besuner, William V. Shourt, Andrew P. Hope

R-FLEX is a compact, low-part-count flexure-based radial positioning mechanism designed for the next generation of massively parallel fiber-fed spectroscopic telescope instruments. Current instruments such as the Dark Energy Spectroscopic Instrument (DESI) employ 5,000 robotic fiber positioners at 10.4 mm pitch, whereas future surveys require 2.5-3x higher packing density, necessitating new positioning technologies. The R-FLEX mechanism converts small rotations at the flexure base into large, ne…

Read →
astro-ph.EP

Revisiting TOI-4438 and TOI-442 planetary systems with new observations from SPIRou and TESS

J. Serrano Bell, G. Hébrard, E. Martioli, R. F. Díaz, L. de Almeida, D. Lorenzo-Oliveira, A. Salmi, C. Dorn et al.

We present a comprehensive re-analysis of two star-planet systems: TOI-4438, an M3.5V star hosting a mini-Neptune in a 7.4-day orbit, and TOI-442, an M1V star with a 4-day period planet located within the hot Neptune desert. Both systems were originally identified as transiting planet candidates by TESS and subsequently validated through the radial velocity (RV) method. Our work incorporates new TESS transit data and high-resolution spectroscopy from the SPIRou near-infrared spectropolarimeter.…

Read →
astro-ph.GA

COSMOS2025: A Machine Learning Census of Massive Quiescent Galaxies at $2.5 < \text{z} < 5$

Vahid Asadi, Hosein Haghi, Akram Hasani Zonoozi

The existence of massive quiescent galaxies at high redshifts ($ \text{z} \gtrsim 2$) strongly constrains the rapid quenching mechanisms in galaxy evolution models. We present a machine learning framework to identify massive ($\log(\text{M}_*/\text{M}_\odot) > 9.5$) quiescent galaxies at $2.5 < \text{z} < 5$ in the COSMOS2025 catalog. We train a \texttt{CatBoostClassifier} on mock photometry from the Santa Cruz semi-analytic models (SAMs), incorporating key JWST NIRCam bands and realistic noise…

Read →
nucl-thastro-ph.HEgr-qc

Neural-Accelerated Bayesian Calibration of Chiral Mean-Field Models to Nuclear Saturation and Vacuum Properties

Isaac Legred, Mateus Reinke Pelicer, Veronica Dexheimer, Jacquelyn Noronha-Hostler, Nicolás Yunes

Chiral models of nuclear interactions provide approximate, phenomenological descriptions of dense matter that respect the symmetries of quantum chromodynamics. Their Lagrangian parameters, however, are difficult to calibrate because these models are not controlled effective theories. Furthermore, repeated model evaluations are computationally expensive, and most parameter choices fail to reproduce acceptable saturation properties or hadron masses in vacuum. To address this, we develop a Bayesian…

Read →
astro-ph.IM

MORFEO: Advancing Towards Final Design

Lorenzo Busoni, Guido Agapito, Marco Bonaglia, Alfio Puglisi, Marco Xompero, Matteo Aliverti, Francesca Annibali, Carmelo Arcidiacono et al.

The Multiconjugate adaptive Optics Relay For ELT Observations (MORFEO) is a first-generation adaptive optics module for the Extremely Large Telescope (ELT), designed to deliver a diffraction-limited, highly uniform 53x53 arcsec field of view to the MICADO near-infrared camera. As the project advances toward its Final Design Review (FDR), significant consolidations have been achieved across all subsystems. This paper presents an updated overview of the MORFEO system, highlighting its dual operati…

Read →
astro-ph.EP

Piercing through the Haze: Characterizing Titan-like terrestrial exoplanets with JWST

L. C. Mayorga, Jacob Lustig-Yaeger, Andrew P. Lincowski, Kathleen E. Mandt, Ryan C. Felton, Adrienn Luspay-Kuti, Kristin S. Sotzen, Cameron A. Gutsgell et al.

As we enter a new era of using JWST to characterize exoplanet atmospheres, a top priority is defining observational needs and parameters in the search for life on an exoplanet. Although some studies have begun to consider Titan-like exoplanet atmospheres, more work is needed to prepare for the potential discovery and characterization of Titan analogues with JWST and future missions. We explore the effectiveness of exoplanet atmospheric retrieval methodologies on the Cassini/VIMS-IR spectrum of T…

Read →
astro-ph.HE

Time-resolved leptonic modeling of the prompt emission of GRB 211211A

Maria Petropoulou, Maria Gkoni, Konstantinos Xyloportas, Stamatios I. Stathopoulos, Georgios Vasilopoulos, Apostolos Mastichiadis

GRB 211211A is a long duration gamma-ray burst with a compact object merger origin. In this work, we model the time-resolved prompt-emission spectra of GRB 211211A within a leptonic radiation framework. Our goal is to infer the physical properties of the emitting region, study the temporal evolution of the radiating particle distribution, and make predictions for prompt emission at TeV energies. We perform Markov Chain Monte Carlo fitting of the time-resolved numerical spectral energy distributi…

Read →
astro-ph.IMastro-ph.EPastro-ph.SR

Rigidity spectra and onset geometry of the two largest Forbush decreases of solar cycle 25 from visibility-graph curvature

D. Sierra-Porta

We apply a geometric network diagnostic -- the nodal Forman-Ricci (FR) curvature of natural visibility graphs (NVG) -- to the two largest Forbush decreases (FDs) of solar cycle 25: the Gannon storm of 2024 May 10-11 and the 2025 June 1 event. Using 30-min NMDB records from six NM64 stations spanning cutoff rigidities $R_c \simeq 0$-$7\,$GV, we show that nodal FR curvature exhibits a sharp, coherent minimum at FD onset in both events, with onset-to-quiet median curvature ratios of 2.5-5.2 (Gannon…

Read →
astro-ph.GAastro-ph.IM

When X-ray Features Hurt: Label Noise and Luminosity Overlap in Machine Learning Classification of AGN and Star-forming Galaxies

Jaymin Ding

In a previous paper, we found that adding an X-ray flux feature to a Random Forest Classifier of active galactic nuclei (AGN) and star-forming galaxies (SFGs) decreased classification accuracy from 97.51% to 89.26%, a counterintuitive result given the prevailing theory that X-rays are a reliable AGN diagnostic. This paper investigates the source of that discrepancy through both astrophysical and machine learning lenses. On the astrophysical side, we show that the X-ray luminosities of AGN and SF…

Read →
astro-ph.EP

Growing Planets Produce Extreme Dust Signatures

Philip J. Carter, Zoë M. Leinhardt

Collisions between planetary bodies are essential to the assembly of rocky planets like the Earth, but they are extremely difficult to observe. We therefore rely on indirect signatures of planetary impacts such as extreme debris disks - bright infrared excesses around other stars. Extreme debris disks are thought to be the result of energetic collisions that ejected large amounts of vaporized rock which rapidly condensed into mm- or cm-sized dust. However, previously there has been no clear way…

Read →
astro-ph.SR

Near-Infrared Observations of BD+44 493 with IGRINS-2

Vinicius M. Placco, William D. Vacca

We present high-resolution (R~45,000), high signal-to-noise (S/N>200) H and K-band spectra of BD+44 493, obtained with the newly commissioned IGRINS-2 instrument on the Gemini North Telescope. BD+44 493 is a well-known carbon-enhanced (CEMP; [C/Fe]=+1.40) ultra metal-poor (UMP; [Fe/H]~-4.0) star that has been extensively studied with high-resolution spectroscopy from the ultraviolet to the infrared. From the IGRINS-2 data, we derive new estimates of the abundances of C, Mg, Si, and Ca by measuri…

Read →
astro-ph.EP

Probing Planet Formation with JWST Spectroscopy of IC348: Sustained Diversity but Limited Chemical Evolution and Pebble Drift

John S. Carr, Joan R. Najita

Inner disk chemistry offers a valuable window onto disk evolution and planet formation. Key planet formation processes, including pebble drift, planetesimal and planet formation, dust traps, and snow lines, determine the delivery rates of oxygen and carbon to the inner disk. As a result, measurements of molecules sensitive to the gas-phase C/O ratio, in disks over a range of ages, can constrain the relative importance and time evolution of these processes. Here we report JWST/MIRI observations o…

Read →
astro-ph.GAastro-ph.HE

Dynamics in Nuclear Stellar Clusters: The Impact of Collisions and Disrupted Binaries

Barak Rom, Re'em Sari

The nuclear stellar clusters surrounding supermassive black holes (SMBHs) host millions of stars and stellar remnants. We study how stellar collisions and binary disruptions, alongside two-body scattering and gravitational-wave (GW) emission, shape the stellar distribution and regulate the abundance of stars on tightly bound orbits. We show the following. (a) Stars in the inner region of the cluster follow a steady-state density profile scaling as $n(r)\propto r^{-5/4}$, set by the balance betwe…

Read →
astro-ph.GAastro-ph.CO

Evaluating the flexibility of the MillenniumTNG galaxy formation model with multi-zoom re-simulations

Francisco Maion, Raul E. Angulo, Volker Springel, Shy Genel, Greg L. Bryan

In this study we introduce a new simulation campaign designed to understand how parameters that control star-formation and AGN feedback processes in cosmological hydrodynamical simulations impact observables such as the galaxy stellar-mass function (GSMF) and the gas fractions in large dark matter halos. These simulations are zoom-ins to halos selected from the MillenniumTNG (MTNG) simulation, and are run employing a novel multi-zoom approach which simultaneously re-simulates several sub-regions…

Read →
astro-ph.HEastro-ph.CO

Semi-supervised morphological classification of fast radio bursts from the second CHIME/FRB catalogue

Bo Lin Fan, Renée Hložek, Antonio Herrera Martin

Understanding the morphology of fast radio bursts (FRB), and whether all sources repeat, are key challenges that are becoming more tractable given the increase in data from surveys such as the Canadian Hydrogen Intensity Mapping Experiment FRB project (CHIME/FRB). We present a Convolutional Autoencoder unsupervised classifier for separating the CHIME/FRB data into morphological classes. This data-driven approach is more reproducible than visual inspection, since groupings are learned from the da…

Read →
hep-phastro-ph.HEhep-ex

The soft volume of ultra-high energy neutrinos experiments

Stefano Palmisano, Diego Redigolo, Michele Tammaro, Andrea Tesi

We develop a semi-analytical framework to map ultra-high-energy neutrino fluxes onto event rates at neutrino telescopes. The formulation is based on the Boltzmann equation for the distribution of secondary muons produced by neutrino interactions in matter, and naturally accounts for the effective target volume relevant for through-going tracks. This "soft volume" is controlled by muon propagation and stochastic energy losses, and can be significantly larger than the instrumented detector volume.…

Read →
astro-ph.HE

Fe K$α$ line from the Broad Line Region of PDS456 with XRISM/Resolve

Alfredo Luminari, Fabrizio Nicastro, Stefano Bianchi, Elias Kammoun

The high-luminosity, high-mass and likely super-Eddington quasar PDS 456 is known for its extremely dynamic environment. A wealth of observational features from the millimetric up to the X-ray band shows energetic outflows at all scales, from accretion disc up to galaxy scales. Broad Emission Lines in the optical and UV show significant widths and line-of-sight velocities. Moreover, NIR interferometry revealed a partially outflowing Broad Line Region. Thanks to the unprecedented energy resolutio…

Read →
astro-ph.EP

Photometric Variability and Rotation of Beta Pictoris b from JWST NIRCam Coronagraphic Imaging

Yifan Zhou, Beth A. Biller, Aarynn L. Carter, Marshall D. Perrin, Michael Poon, Genaro Suárez, Ben J. Sutlieff, Johanna M. Vos et al.

We report the detection of photometric variability in the directly imaged super-Jupiter $β$ Pictoris b. Using JWST NIRCam dual-band coronagraphic imaging, we conducted a 16-hour continuous photometric monitoring campaign in the F210M and F410M filters. We developed and validated a time-series photometry framework that combines PSF subtraction, principal component analysis for systematic noise removal, and injection-and-recovery tests to confirm signal fidelity. Both light curves show consistent…

Read →
astro-ph.COastro-ph.GA

Here, There and Everywhere: How AGN jets affect galaxy cluster environments

Isaac Rosenberg, Martine Lokken, Renée Hložek, Weiguang Cui, Sara Santoni, Romeel Davé

Active galactic nuclei (AGN) feedback via black hole-driven jets and winds plays a key role in redistributing matter across megaparsec scales. However, the implementation of jet feedback in cosmological simulations remains highly prescriptive, leading to uncertainties in the predicted state of the Warm-Hot Intergalactic Medium and other extragalactic observables. We investigate how variations in AGN jet velocity, orientation, and delayed hydrodynamic coupling impact the thermodynamic state of ga…

Read →
astro-ph.HE

Synchrotron Emission from Cooled Particle Distributions

Ross Ferguson, Ben Margalit

Synchrotron emitting electrons can lose energy (`cool') through various processes including radiative losses (e.g., synchrotron or inverse-Compton cooling) and adiabatic expansion. Such cooling will shift electrons in energy-space and therefore change the electron distribution function. This in turn alters the nature of synchrotron emission and absorption from these electrons. In past literature these effects have typically been considered using either simplified one-zone frameworks, or using nu…

Read →
astro-ph.EP

On the Detectability of Volcanic Exo-Ios That May Fuel Auroras on Super-Jupiters

Brooke Kotten, Mary Anne Limbach, Johanna M. Vos, Merle Schrader, Allison McCarthy, Melodie M. Kao, Mikayla J. Wilson, Andrew Householder et al.

Studies suggest Jupiter's aurorae are supplied with plasma from volcanic outflows on the planet's innermost moon, Io. Repeating bursts of radio emission thought to trace massively scaled-up analogs of Jupiter's aurorae have been detected around nearly a dozen isolated substellar worlds, yet the source of the electrons fueling the aurorae remains unknown. Volcanism from tidally heated exosatellites may provide the plasma that fuel the aurora on these worlds. We assess whether transit observations…

Read →
astro-ph.SR

Simulating the convection in red super-giant stars: wobbling jets in common envelope evolution

Shlomi Hillel, Ron Schreier, Noam Soker

We use our newly constructed three-dimensional red supergiant (RSG) stellar model, which also mimics nuclear energy production and photospheric emission, to calculate the stochastic component of the angular momentum of the mass that a companion spiraling within the RSG's envelope accretes during common envelope evolution (CEE). The accreted mass has a fixed-direction angular-momentum component arising from the density gradient in the RSG envelope and orbital motion. The angular momentum componen…

Read →
astro-ph.SRastro-ph.GA

The Carbon-Dependent Binary Frequency of CEMP-no Stars

John D. Dixon, Terese T. Hansen, Jennifer Marshall, Vinicius M. Placco, Timothy C. Beers, Anke Ardern-Arentsen, Birgitta Nordström, Lauren N. Aldoroty et al.

Studies of the oldest and most metal-poor stars in the Milky Way have confirmed a common abundance signature of high carbon enrichment, coupled with a subsolar abundance pattern of neutron-capture elements. The so-called CEMP-no stars have been speculated to be bona fide population II stars, potentially tracing the nucleosynthesis of the very first stars formed in the universe. However, constraining the binary nature of CEMP-no stars is crucial for understanding their abundance patterns. In prev…

Read →
astro-ph.HE

Gamma-ray Modes in a Transitional Pulsar

Maksat Satybaldiev, Manuel Linares

Transitional millisecond pulsars (tMSPs) exhibit a unique sub-luminous disk state, at the cross-roads between accretion and rotation power, where they switch between two distinct X-ray modes. We present the discovery of gamma-ray modes in PSR J1023+0038, the first confirmed tMSP, from stacking Fermi-LAT data during the modes (which we identify using simultaneous X-ray observations). Surprisingly, we find that gamma-rays and X-rays are anti-correlated during this mode switching: the gamma-ray flu…

Read →
gr-qcastro-ph.HEhep-phhep-th

Antikick Relation in High-Energy Head-On Collisions of Spinning Black Holes

Carlos O. Lousto, James Healy, Alessandro Ciarfella, Hiroyuki Nakano

The collision of black holes at relativistic speeds probes gravity in its most extreme dynamical regime. While the maximum gravitational recoil from \emph{grazing} high-energy collisions ($\approx28\,562$~km/s, i.e., $\sim0.1c$) and the maximum radiated energy $E_{\rm rad}$ and remnant spin $α_f^{\max}$ from such encounters ($E_{\rm rad}/M_{\rm ADM}\approx32\%$ where $M_{\rm ADM}$ is the ADM mass, and $α_f^{\max}\approx0.987$) have been established previously~\cite{Healy:2022jbh,Healy:2024lhl},…

Read →
astro-ph.GAastro-ph.CO

Alignment of the Milky Way and M31 with their cosmic environment. New insights from constrained Local Group simulations

Hanneke C. Woudenberg, Amina Helmi, Ewoud Wempe, Anna Genina, Simon D. M. White, Jens Jasche, Guilhem Lavaux

The large-scale environment is thought to play an important role in setting galaxy properties. The Milky Way (MW) and Andromeda (M31) reside in the Local Group, embedded in the Local Sheet (LS). To study the sheet's influence on the dark matter (DM) halo shapes, spins, and disks orientations of MW and M31 analogues, we use a new suite of constrained Local Group simulations that reproduce the observed configuration of the two main halos and the LS. We determine their shapes and alignments relativ…

Read →
astro-ph.IMphysics.ins-det

picoMUX: microcontroller based time-domain multiplexing readout for kilopixel TES arrays

Simon Tartakovsky, Alexandre E. Adler, Jason E. Austermann, Steven J. Benton, Shannon M. Duff, Malcolm Durkin, Jeffrey P. Filippini, Aurelien A. Fraisse et al.

Advances in cryogenic SQUID-based time-domain multiplexing (TDM) have outpaced their warm readout electronics. Next generation CMB telescopes are baselining kilopixel TES arrays with few viable electronic options. We present picoMUX, a new TDM readout electronics architecture that replaces the FPGA typically used in such systems with a complement of modern microcontrollers. Designed around the current generation NIST multiplexer, it fully exploits its differential nature and two-level switching.…

Read →
astro-ph.EP

When Stabilizing Feedbacks Wreak Havoc in Habitable Planets: Chaos at the Freezing Point in a Four-Feedback Climate Model

Chaucer Langbert, Dániel Apai, Renu Malhotra

The long-term habitability of Earth-like planets is governed by the balance of positive and negative climate feedbacks that regulate surface temperature and atmospheric composition. While some feedbacks, such as ice-albedo and silicate weathering, are thought to operate on many terrestrial planets, the number and strength of additional climate feedbacks may vary substantially from world to world. An important open question is whether and how the introduction of an additional climate feedback inf…

Read →
astro-ph.HEgr-qc

A new model for the continuum spectra of AM CVn binaries and multi-messenger inference with normalizing flows

Nathan Steinle, Samar Safi-Harb, Austin MacMaster, Liliana Rivera Sandoval, Katelyn Breivik, Tyrone E. Woods, Tom Maccarone, Tom Wagg et al.

Future electromagnetic telescopes, such as $\textit{NewAthena}$, $\textit{CASTOR}$, and an $\textit{AXIS}$-like mission, along with milli-Hz gravitational-wave (GW) detectors such as $\textit{LISA}$, are expected to unearth the population of Galactic ultra-compact binaries (UCBs). Joint multi-messenger detections will probe the uncertain formation, evolution, and observables of mass-transferring UCBs such as AM CVns, but theoretical tools need to be advanced to anticipate future data challenges.…

Read →