UchUchU

Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GAphysics.data-an

Changing-Look AGNs from DESI. VI. Host Galaxies

Shengxiu Sun, Linhua Jiang, Wei-Jian Guo, Sarah E. I. Bosman, Zhiwei Pan

Changing-look (CL) AGNs trace rapid changes in nuclear activity, but their connection to host galaxy properties remains unclear. We present a study of the host galaxies of 105 CL AGNs previously selected by comparing DESI and SDSS data. We apply a two-epoch spectrophotometric decomposition to the DESI and SDSS spectra of the 105 objects. Meanwhile, HSC images are used to constrain their varying AGN components and non-varying stellar population components. We find that 79 of the 105 (75.2%) CL AG…

Read →
astro-ph.GAastro-ph.IM

Quiescent Host Galaxies of Extended Quasars Revealed by Spectrophotometric Decomposition

Shengxiu Sun, Linhua Jiang, Zhiwei Pan, Małgorzata Siudek, Mar Mezcua, Gaocheng Yin, Swayamtrupta Panda, Wei-Jian Guo et al.

Previous works of low-redshift quasar host galaxies have focused on compact quasars and found that their host galaxies are mainly star-forming galaxies. Here we present a study of host galaxies for quasars with extended morphologies in ground-based optical images. We select a sample of more than 1000 type 1 quasars at redshift $0.1<z<1$ that are classified as extended objects by DESI. Combining high-resolution spectra from DESI and high-quality images from Subaru HSC, we develop a spectrophotome…

Read →
astro-ph.SRastro-ph.GA

The s-process at Subsolar Metallicity: Insights from High-Resolution Infrared Spectroscopy of Magellanic Cloud Planetary Nebulae

N. C. Sterling, M. G. Stephenson, Harriet L. Dinerstein, A. Yagüe-López, Kyle F. Kaplan, J. Beaumont, Maria Lugaro, Amanda I. Karakas et al.

We present observations of 12 Magellanic Cloud planetary nebulae (PNe) obtained with the high-resolution near-infrared spectrometer IGRINS on Gemini South. In 10 targets we detect multiple neutron(n)-capture elements that can be synthesized by the s-process during the preceding asymptotic giant branch (AGB) phase, including the widely-observed species Se and Kr, and first detections of Rb, Cd, and Te in extragalactic PNe. The derived abundances significantly expand the inventory of trans-iron el…

Read →
astro-ph.IM

End-to-end differentiable retrieval of molecular spectra using hydrodynamics, chemistry, and radiative transfer

T. Grassi, G. Vermariën, J. E. Pineda, S. Spezzano, S. Bovino, P. Caselli

We aim to reproduce observed molecular line emission using a pipeline that couples hydrodynamics, chemistry, and radiative transfer, capable of simultaneously optimizing all relevant physical and chemical parameters. We developed an end-to-end differentiable Jax pipeline consisting of a custom hydrodynamical code, a modified version of the differentiable chemical code Carbox, and a custom radiative transfer code. We tested the framework using controlled synthetic data. We demonstrate that the fr…

Read →
astro-ph.SR

A New Sirius-like System at Only 21 Parsecs: An Elusive White Dwarf Companion to the Nearby K-dwarf HD 38230

Alexander Venner, Logan A. Pearce, Qier An, Clémence Fontanive, Elisabeth C. Matthews, Kyle Franson, Justin R. Crepp, Hai Fu et al.

White dwarfs are among the rarest and faintest stars found in the solar neighbourhood and are therefore persistently challenging to detect. Whereas the \textit{Gaia} mission has vastly expanded our knowledge of isolated white dwarfs, limited contrast sensitivity means that white dwarfs companions to much brighter solar-type stars are easily missed, leaving a subset of white dwarfs in "Sirius-like systems" that can only be discovered via high-contrast imaging. Here we report the discovery of a wh…

Read →
astro-ph.HE

Deep Learning-Based Classification and Analysis of Pulsar Candidates in Fermi-LAT Unassociated Sources

C. Pozo González, R. López-Coto, J. Méndez-Gallego, E. de Oña Wilhelm

The Large Area Telescope (LAT) has revolutionized our understanding of the high-energy sky, yet approximately one-third of the sources in the Fourth Fermi-LAT Source Catalog (4FGL) remain unassociated. Conventional machine learning, such as Decision Trees, often treat spectral features as independent tabular entries, neglecting the sequential topological information inherent in the Spectral Energy Distribution (SED). We aim to classify unassociated Fermi-LAT sources by exploiting the intrinsic s…

Read →
astro-ph.EPastro-ph.SR

Atmospheric Signatures of Common Envelope Evolution in White Dwarf Planets

Sydney Jenkins, Andrew Vanderburg, James Mang, Juliette Becker, Caroline V. Morley, Melinda Soares-Furtado, Ricardo Yarza

The majority of confirmed exoplanets orbit within 1 au of a main-sequence (MS) star. When their stellar hosts evolve off the MS, many of these planets will be engulfed and destroyed, creating empty "forbidden" zones around the stars as they evolve to their final state as a white dwarf (WD). However, several confirmed and candidate WD planets have been found within this forbidden zone. Two formation scenarios have been proposed to explain the existence of these close-in planets: high-eccentricity…

Read →
astro-ph.GAastro-ph.CO

Searching for Population III stars with line intensity mapping cross-correlations

Sahil Hegde, Guochao Sun, Julian B. Muñoz, Steven R. Furlanetto

Decades of searches for Population III stars in individual galaxies have yielded a few potential candidates, but a statistically robust characterization of the demographics of the first stars in the lowest-mass systems remains elusive. Line intensity mapping (LIM), an observational technique that measures fluctuations in the aggregate emission from the entire galaxy population --- including the faintest sources --- offers an alternative strategy that is especially well-suited for the Pop III era…

Read →
astro-ph.HE

Peering through the dip: IXPE unveils the extended scattering environment of GX 13+1

Alessandro Di Marco, Fabio La Monaca, Luigi Stella, Anagha P. Nitindala, Alexandra Veledina, Anna Bobrikova, Eleonora Veronica Lai, Alessandro Papitto et al.

Neutron star low-mass X-ray binaries feature complex accretion geometries, often including an accretion disk corona or disk winds. Here, a study of the highly inclined dipping source GX 13+1, using coordinated observations from the IXPE, NuSTAR, and Swift-XRT, is presented; this is the first time that such a campaign was conducted to monitor its periodic dip. Our analysis reveals significant variations in polarimetric properties tracking the dip. At the center of the dip, the polarization degree…

Read →
astro-ph.GA

Misaligned or chaotic? A strong break of axial symmetry in the local LRD J1025 revealed with VLT/FORS2 spectropolarimetry

Francesco D'Eugenio, Gabriele Pezzulli, Roberto Maiolino, Alessandro Marconi, Xihan Ji, Cristina Ramos Almeida, Andrea Ferrara, Piero Madau et al.

Little Red Dots (LRDs) are compact active galactic nuclei (AGN) with unusual spectral energy distributions and broad Balmer emission, candidate signposts of rapid black-hole growth. We present VLT/FORS2 optical linear spectropolarimetry of the closest known LRD, SDSS J102530.29+140207.3, at z=0.1. In total light, we detect spatially extended narrow-H$α$ emission, probably tracing the host galaxy. We measure a nearly grey continuum polarisation $p_{\rm cont}=1.53\pm0.04$(rand.)$\pm$0.20(syst.) pe…

Read →
astro-ph.HEgr-qc

A Four-dimensional Model-agnostic Probe into the Astrophysical Origins of Binary Black Hole Subpopulations

Anarya Ray, Vicky Kalogera

There is strong evidence of multiple binary black hole~(BBH) subpopulations in the cumulative gravitational wave catalog by the LIGO-Virgo-KAGRA collaboration that likely originate through distinct evolutionary channels. The astrophysical interpretation of this complex underlying population is subject to theoretical uncertainties in treatments of binary stellar evolution, core collapse, and host environments. Due to a lack of robust predictions and the sheer diversity of plausible features, stro…

Read →
astro-ph.IMastro-ph.EP

Laboratory demonstration of low order wavefront control using light reflected off the vortex coronagraph

Clarissa R. Do Ó, Kane Sjoberg, Luke Lamitina, Susan Redmond, Dimitri Mawet, Jorge Llop-Sayson, Siria Alicata

The Astro2020 Decadal Survey identified exoplanet imaging as a high priority for the Habitable Worlds Observatory (HWO), which must image and characterize exo-Earths at contrasts of $1\times10^{-10}$. The vector vortex coronagraph (VVC) is a leading architecture for this task owing to its small inner working angle and high throughput. Using light reflected from the VVC for wavefront sensing and control provides a potential path to improving robustness to residual wavefront errors and minimizing…

Read →
astro-ph.GA

Characterizing the disruption of Böotes III: a missing link in the Galactic halo?

Jaclyn Jensen, Daniel A. Boyea, Alan W. McConnachie, Raphaël Errani, Akshara Viswanathan, Nicolas Martin, Zhen Yuan, Guillaume F. Thomas et al.

The Böotes III (Boo3) dwarf galaxy has long been suspected of being the progenitor of Styx, a ~50°-long stellar stream that was simultaneously discovered in the same region of sky. Boo3's diffuse morphology, large velocity dispersion, small pericenter, and excess of candidate stars at large radii suggest it is undergoing active tidal disruption. A link to Styx is therefore logical; however, a clear connection between these structures has not yet been clearly demonstrated. Here, we re-examine the…

Read →
astro-ph.COastro-ph.GAhep-ph

Dark Matter Constraints from Small-Scale Cosmic Structure

Ethan O. Nadler, Keir K. Rogers, Alex Drlica-Wagner

Small-scale cosmic structure provides a powerful test of the fundamental nature of dark matter (DM). A wide range of DM models impact matter clustering on small scales, including warm, fuzzy, and (self-)interacting DM. In these scenarios, DM physics such as free-streaming, wave interference, and self/Standard Model interactions alter the abundance and internal structure of DM halos. Cosmological and astrophysical probes of nonlinear structure---including dwarf galaxies, strong lensing, the Lyman…

Read →
astro-ph.IMastro-ph.EP

Upgrading LBTI/NOMIC with a quadruple annular groove phase mask and GeoSnap detector for imaging nearby, habitable-zone exoplanets

Kevin Wagner, Manny Montoya, Steve Ertel, Jarron Leisenring, Pontus Forsberg, Samuel Ronayette, Andre Wong, Mikael Karlsson et al.

The Large Binocular Telescope Interferometer (LBTI)'s Nulling-Optimized Mid-Infrared Camera (NOMIC) is among the most capable thermal-infrared imaging systems available for high-contrast, high-angular-resolution astronomical observations. Here we describe two in-progress upgrades to LBTI/NOMIC: (1) the design, fabrication, and installation of a quadruple annular groove phase mask (Q-AGPM) coronagraph, and (2) the installation of a 13 micron-cutoff Teledyne GeoSnap array. The Q-AGPM is the first…

Read →
astro-ph.HE

Spinning down neutron-star merger remnants with the Tayler-Spruit dynamo: Global simulations reveal the formation of massive disks and neutron-rich ejecta

Harry Ho-Yin Ng, Elias R. Most

Magnetic-field amplification and angular momentum (AM) transport critically shape the secular evolution, lifetime, and electromagnetic signatures of binary neutron-star merger remnants. While the magnetorotational instability can operate in the outer negative-shear regions of the neutron-star remnant and accretion disk, the positive-shear, stably stratified core may instead be susceptible to the Tayler-Spruit dynamo. We present the first global, long-term general-relativistic neutrino-radiation…

Read →
astro-ph.HEgr-qc

Search for gravitational waves associated with high-energy neutrinos detected by IceCube during the third observing run of LIGO-Virgo

Matthias Vereecken, Matteo Pracchia, Kara Merfeld, Iara Tosta e Melo, Wasim Javed, Patrick Sutton

We search for generic gravitational-wave transients associated with high-energy neutrinos detected by the IceCube Neutrino Observatory during the third Observing Run (O3) of Advanced LIGO, Advanced Virgo, and KAGRA. We perform an unmodeled, targeted search, which is sensitive to gravitational-wave signals weaker than those reported in real time or in the gravitional-wave transient catalog, and can thus uncover coincidences missed by typical neutrino follow-up searches. We find no statistically s…

Read →
astro-ph.SRphysics.plasm-ph

The Diagnostic Temperature Discrepancy as a Kinetic Measurement: Shape, Transport, and Termination of the Suprathermal Electron Tail

Victor Edmonds

Two standard thermometers applied to the same quiet-Sun corona disagree by a stable factor: radio brightness reads about 0.6 MK while ionization- and scale-height-based diagnostics read about 1.5 MK, a ratio of 2.4 +/- 0.3 over eight years. We argue this discrepancy is not an anomaly awaiting reconciliation but a kinetic measurement, and we read it three times: for the shape of the electron distribution, for its origin, and for the energy where it must end. First, a temperature diagnostic is a p…

Read →
astro-ph.SRphysics.plasm-ph

The Diagnostic Temperature Discrepancy as a Kinetic Measurement: Shape, Transport, and Termination of the Suprathermal Electron Tail

Victor Edmonds

Two standard thermometers applied to the same quiet-Sun corona disagree by a stable factor: radio brightness reads about 0.6 MK while ionization- and scale-height-based diagnostics read about 1.5 MK, a ratio of 2.4 +/- 0.3 over eight years. We argue this discrepancy is not an anomaly awaiting reconciliation but a kinetic measurement, and we read it three times: for the shape of the electron distribution, for its origin, and for the energy where it must end. First, a temperature diagnostic is a p…

Read →
astro-ph.HE

Same explosion, many faces: numerical modeling reveals viewing angle as a driver of diversity for core-collapse SNe in binary systems

Soham Mandal, Raphael Baer-way, Shazrene Mohamed, Irene Salmaso, Poonam Chandra, Maryam Modjaz

Observable properties of core-collapse supernovae (CCSNe) depend sensitively on the circumstellar material (CSM) formed by pre-explosion mass loss from the progenitor star. Since a large fraction of CCSN progenitors reside in binaries, both the progenitor structure and surrounding CSM can be significantly impacted by binary interaction. Yet, its impact on the observed CCSN landscape remains poorly constrained. In this work, we investigate CCSNe from binary systems undergoing stable Roche lobe ov…

Read →
hep-phastro-ph.COastro-ph.GA

Dynamical flattening of halo density cusps by Q-ball dark matter

Alexander Libanov, Sergey Troitsky

Cold, collisionless dark matter successfully explains a wide range of observations, including the formation of large-scale structure. Nevertheless, tensions remain on small, galactic scales, most notably the cusp-core, or inner-mass-deficit, problem and the diversity of inner rotation-curve shapes and central densities at fixed halo mass. These observations suggest that additional dark-sector physics may affect the inner structure of halos, although no generally accepted explanation has yet emer…

Read →
physics.hist-phastro-ph.IMphysics.class-phphysics.ed-ph

De mora luminis: Roemer's discovery 350 years later

Fabio Falchi, Riccardo Furgoni, Paolo Gattillo, Maurizio Francesio

350 years from the 1676 announcement of the Roemer's discovery that light propagates with finite speed, we present our observations using eyes with telescopes having similar resolution compared to those in the late 17th century. We confirmed that Roemer's method is valid and gives reasonable values for the speed of light c, within about 10 per cent of the modern value for our measurements, even with the simplest modelling technique, using uniform circular motions. We found that increasing the co…

Read →
astro-ph.HEastro-ph.IM

Uncertainty-Aware Tidal Disruption Event Classification : A Host-Agnostic Probabilistic Random Forest Approach

Vysakh Anilkumar, Sjoert van Velzen, Marek Kowalski, Simeon Reusch

The classification of Tidal Disruption Events in large-scale photometric surveys is challenging because deterministic machine learning models produce overconfident misclassifications under varying data quality and low signal-to-noise conditions. Existing lightcurve-based approaches fail to incorporate measurement uncertainties, consequently generating brittle outputs. We present a host-agnostic, uncertainty-aware classification framework using a Probabilistic Random Forest (PRF). Our pipeline ex…

Read →
astro-ph.SR

PRICM3: A novel Polarization Ratio framework for three-dimensional CME reconstruction

Yara De Leo, Manuela Temmer, Fernando M. López, Sarah E. Gibson, Hebe Cremades, Leonardo Di Lorenzo, Roberto Susino, Marco Romoli et al.

Coronal mass ejections (CMEs) are inherently three-dimensional (3D), but traditional white-light coronagraphs provide only two-dimensional (2D) projections. While the Polarization Ratio Technique (PRT) utilizes Thomson scattering to infer proxy 3D plasma locations, its results are typically limited to 2D topographical maps, hindering geometric interpretation. To address this, we introduce PRICM3 (Polarization Ratio Integrated CME Mapper in 3D), a framework that converts PRT-derived maps into exp…

Read →
astro-ph.GAastro-ph.HE

X-ray Absorption Variability in NGC 1142: Another Constraint on the Nature of the Torus/Broad-Line Region in Active Galactic Nuclei

Isaiah S. Cox, Núria Torres-Albà, Stefano Marchesi, Vittoria E. Gianolli, Xiurui Zhao, Marco Ajello, Indrani Pal, Andrealuna Pizzetti et al.

The physics, geometry, and kinematics of the gas and dust surrounding the central engine of active galactic nuclei (AGN) are not well understood. In some sources, this material obscures the coronal X-ray emission, allowing its line-of-sight column density ($N_H$) to be measured. Many sources display $N_H$ variability across multiple epochs. Studying this variability can provide information about the distribution and dynamics of the obscuring material. Particularly, previous works have shown that…

Read →
astro-ph.IM

DB-Bench: Benchmarking Deblenders for LSST DESC Using the Blending ToolKit

Aidan Berres, Grant Merz, Xin Liu, the LSST Dark Energy Science Collaboration

Blending will be a major source of systematic uncertainty in downstream science analyses of LSST data. We benchmark the performance of several deblenders, leveraging the Blending ToolKit (BTK) to perform rigorous, end-to-end testing. This benchmark incorporates key deblending algorithms, including SourceExtractor, SCARLET, and DeepDISC, with the goal of comparing their effectiveness in handling blended galaxy images from LSST/Rubin simulations. A key focus is characterizing algorithm performance…

Read →
astro-ph.IM

DB-Bench: Benchmarking Deblenders for LSST DESC Using the Blending ToolKit

Aidan Berres, Grant Merz, Xin Liu, Éric Aubourg, Cécile Roucelle, the LSST Dark Energy Science Collaboration

Blending will be a major source of systematic uncertainty in downstream science analyses of LSST data. We benchmark the performance of several deblenders, leveraging the Blending ToolKit (BTK) to perform rigorous, end-to-end testing. This benchmark incorporates key deblending algorithms, including SourceExtractor, SCARLET, and DeepDISC, with the goal of comparing their effectiveness in handling blended galaxy images from LSST/Rubin simulations. A key focus is characterizing algorithm performance…

Read →
astro-ph.IM

Statistical treatment of searches for counterparts of positionally-uncertain astrophysical sources: from flux upper limits to detection

Julian Sitarek, Abelardo Moralejo, Juan Jiménez Quiles, Giacomo D'Amico, Andrea Simongini, Antonio Stamerra

Rapid growth of the multimessenger and multiwavelength astrophysics had led to an increasing number of observations of the same events with instruments with different point spread functions. In particular pointing instruments with good angular resolution are used to pin-point the source of poorly-localized alert. In case no clear detection of the source counterpart is reached, the interpretation of the results requires statistical analysis. We investigate two approaches using the probability den…

Read →
astro-ph.SR

Magnetic Reconnection Process in Partially Ionized Fluids: Insights from the Solar Chromosphere

Adrian R. Montañez-Lobo, Fabio D. Lora-Clavijo

Magnetic reconnection converts stored magnetic energy into kinetic energy, heat, and radiation. While extensively studied in fully ionized plasmas, observations show that ionization and recombination also play a role by modifying the local plasma resistivity and enabling additional heating channels. This study examines magnetic reconnection in the partially ionized solar chromosphere, analyzing its morphology and energy releases with attention to elastic collisions, ionization, and recombination…

Read →
astro-ph.HEastro-ph.COnucl-th

Binary neutron stars in the next-generation era: Multi-messenger detection prospects and constraints on the equation of state, mass distribution, and cosmology

Hauke Koehn, Thibeau Wouters, Gilad Sadeh, Peter T. H. Pang, Mattia Bulla, Chris Van Den Broeck, Michael W. Coughlin, Tim Dietrich et al.

Next-generation gravitational-wave (GW) observatories will provide crucial insights into the nature of neutron star (NS) matter and the cosmological expansion history. We estimate the number of multi-messenger detections from binary neutron stars (BNS) with the Einstein Telescope (ET) and Cosmic Explorer (CE), and project the resulting constraints on the equation of state (EOS), BNS mass distribution, and cosmology via joint hierarchical Bayesian inference. Assuming a local merger rate of 106.6…

Read →