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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.HE

The angular structure of the GW170817 jet from prompt emission alone

R. Moradi, R. Ruffini

We determine the angular structure of the GW170817 jet by the prompt emission alone, without afterglow fitting, circumburst density or microphysical parameters. We assume that GRB 090510 and GW170817 have outflows of the same kind, observed respectively on-axis and at the interferometric viewing angle of $20^\circ$. We support this assumption with independent gravitational-wave data showing compatible binary masses and radiated energies. We show that for an observer whose beaming cone is filled…

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astro-ph.HE

Through a glass, darkly: a combined framework for estimating fast radio burst host galaxy and population properties in an era of uncertain host identification

C. W. James, B. C. Andersen, L. Marnoch, J. L. Hoffmann, N. Loudas, J. X. Prochaska, S. D. Ryder, M. Woodland et al.

The identification of fast radio burst (FRB) host galaxies, and subsequently their redshifts ($z$), has allowed the FRB dispersion measure (DM) to be used to probe the cosmological distribution of ionised gas, and study the properties of the FRB population itself. However, current methods cannot account for FRBs with uncertain host galaxy associations, leading to underutilisation of data, and potential biases towards nearby, bright hosts. In this work, we develop a methodology which can. We do s…

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astro-ph.HE

Evidence of Orbital Evolution of Gigahertz-Peaked Spectra in Binary Millisecond Pulsar

Rahul Sharan, Bhaswati Bhattacharyya

We present the first systematic investigation of the continuous orbital evolution of the Gigahertz-Peaked Spectum turnover frequency ($ν_{peak}$) in the binary millisecond pulsar, PSR J2144$-$5237. Using approximately 50 hours of densely sampled observations spanning the $\sim10$-day orbit with the Parkes Ultra-Wideband Low frequency receiver, we obtained continuous frequency coverage from 704 MHz to 4 GHz, enabling robust measurements of the spectral evolution throughout the binary orbit. We de…

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astro-ph.IM

Validating the SCALES DRP: A Performance Study of the Medium-Resolution IFS Mode

Athira Unni, Steph Sallum, Max Brodheim, Rosalie McGurk, Andy Skemer, Matthew Brown, Peyton Benac, Michael P. Fitzgerald et al.

We present a performance verification of the medium-resolution integral field spectrograph (IFS) mode of the SCALES Data Reduction Pipeline (SCALES-DRP) using data obtained during recent cryogenic cooldown testing. SCALES (Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy), scheduled for deployment on the Keck II Telescope in late 2026, will be the first facility-class high-contrast thermal-infrared IFS, operating over the 2-5 micrometer wavelength range. The SCALES-DRP, develope…

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astro-ph.HEcs.LGhep-ex

A Differentiable Neural Surrogate for Photon Propagation in Neutrino Telescopes

Felix J. Yu, Berthy T. Feng, Nicholas Kamp, Carlos A. Argüelles

Large-volume neutrino telescopes infer neutrino properties from Cherenkov light, but simulating the transport of billions of photons through highly scattering ice or water is computationally costly. We introduce candela, a differentiable SIREN neural field that learns the photon Green's function of the IceCube Neutrino Observatory, a cubic-kilometer detector embedded in Antarctic glacial ice. Given a point-like energy deposit and sensor, it predicts the expected photon yield and full arrival-tim…

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astro-ph.EPastro-ph.IM

Retrieving Ocean Glint Reflectance Signatures from Directly Imaged Earth-like Exoplanets

Eleanor Cornish, Tyler D. Robinson

Future space telescopes searching for extraterrestrial life require methods to detect environments that can potentially support life. Liquid water is considered essential for life as we know it and its presence is therefore an important observable when characterizing potentially Earth-like exoplanets. Remotely inferring the presence of surface liquid water on a world from spatially unresolved observations is an outstanding challenge where the detection of ocean glint could provide supporting evi…

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astro-ph.EPastro-ph.IM

A Cross-Laboratory Comparison Study of Titan Haze Analogs: Surface Energy II

Eric C. Austin, Xinting Yu, Chao He, Cara Pesciotta, Ella Sciamma-O'Brien, Joshua A. Sebree, Jose Raul Montes-Bojorquez, Adis Husić et al.

The organic haze particles on Titan play important roles in atmospheric cloud formation and aerosol-lake interactions. These processes are strongly influenced by the surface energy of the haze particles, which controls cohesion and wetting behavior. This study presents a comparative analysis of 32 laboratory-produced haze analog samples ("tholins") synthesized across three laboratories. Using contact angle measurements, we determine the total surface energy and its dispersive and polar component…

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astro-ph.GA

Star Formation Evolution in Galaxy Pairs: Constraints from Morphological Disturbances and Recent Star Formation Histories

Shaoze Geng, Shuai Feng, Shuhao Chen, Yaotian Duan, Shiyin Shen, Cailu Shi, Linlin Li, Yijin Niu et al.

Galaxy interactions can enhance star formation, but how star formation evolves during galaxy interactions remains poorly constrained by observations. We combine pair separation, morphological disturbance, and recent star formation history to study this evolution. We measure morphological disturbance with the shape asymmetry parameter ($A_{\rm shape}$) using deep images from the DESI Legacy Surveys, and use Galaxy Zoo DESI classifications as an independent test. We infer recent star formation his…

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astro-ph.COastro-ph.IM

Implementation of frequency-correlated noise in CMB component separation: Method, Validation, and Early Applications

L. Zapelli, M. Bersanelli, L. P. L. Colombo, A. Mennella, L. G. Bachar, E. Battistelli, I. Bekkaoui, L. A. Bianchi et al.

Parametric component separation methods used in cosmic microwave background (CMB) analyses commonly assume instrumental noise to be uncorrelated between frequency channels. This approximation may become insufficient for experiments whose design naturally introduces cross-channel correlations, such as interferometric or multi-band bolometric systems. This work aims to provide a consistent framework to include frequency-correlated noise in Commander2 and to quantify its impact on component separat…

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nucl-thastro-ph.SR

Breakdown of the Plane-Wave Trojan Horse Analysis of the $^{12}\mathrm{C}+{}^{12}\mathrm{C}$ Fusion Reaction: Critical Role of Coulomb Distortions

Akram Mukhamedzhanov

Recently, a new Trojan Horse Method (THM) measurement of carbon-carbon fusion was reported by Li \textit{et al.} [Phys. Lett. B (2026) 140675]. The purpose of the present work is to demonstrate the breakdown of the plane-wave approximation used in the analysis of these data and the critical role of Coulomb distortions in the initial and final states. The reaction mechanism underlying the THM analysis of the $^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion reaction using the $^{16}\mathrm{O}+{}^{12}\ma…

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astro-ph.HE

Preferential accretion onto eccentric and unequal binary black holes

Stanislav DeLaurentiis, Zoltán Haiman, Magdalena Siwek

Supermassive binary black holes (SMBBHs) are expected to be surrounded by circumbinary disks (CBDs) which affect the binary through gravitational forces and accretion. It has been reported that the binary can experience ``preferential accretion'' where one black hole (BH) out-accretes the other for hundreds of orbits, but this asymmetry has yet to be fully described or understood. In this work, we utilize a suite of 80 SMBBH hydrodynamical simulations with varying mass ratios ($q_b$) and eccentr…

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astro-ph.IM

Identifying Casual SETI Transmissions and Ultra-Faint RFI with Cumulant Imaging

Miguel F. Morales

Techniques for identifying radio beacons transmitted by extra-terrestrial civilizations are well advanced. However, the casual broadband emission from standard radio communication is much harder to detect, and counter-intuitively casual Earth radio transmissions are becoming more difficult to identify as we more efficiently utilize the radio spectrum. In this paper we examine the electric-field statistics behind radio communication and re-conceptualize standard radio imaging as the first non-zer…

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astro-ph.EP

Circumbinary planets in coplanar triple-star systems: I. Minimum eccentricity variation region

Emmanuel Gianuzzi, Mario Sucerquia, Nicolás Cuello, Cristian Giuppone

We aim to determine the conditions under which Lidov-Kozai oscillations can arise for circumbinary planets in hierarchical triple-star systems, and to identify the orbital regions where competing secular perturbations minimize eccentricity excitation. We analyzed the statistical properties of hierarchical triples from the Multiple Star Catalog to construct representative synthetic configurations. We then performed N-body simulations of circumbinary planets embedded in these systems, systematical…

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hep-phastro-ph.SRcond-mat.stat-mechnlin.AO

Stability of Collective Neutrino Oscillations -- A Distributional Approach

Rupak Majumder, Dwaipayan Mukherjee, Shamik Gupta, Basudeb Dasgupta

We study the stability of collective neutrino oscillations using a distributional approach motivated by the statistical mechanics of Kuramoto synchronization. Treating the ensemble of neutrino flavor polarization vectors in the thermodynamic limit $N\to\infty$, we derive an exact nonlinear Fokker--Planck (continuity) equation for the one-body distribution $F(\vec{\mathbf{S}},ω,t)$ on the flavor sphere. This equation admits a two-parameter family of azimuthally symmetric stationary solutions, who…

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astro-ph.GA

KKR 18: A Late Arrival Galaxy?

R. Brent Tully, Valentina E. Karachentseva, Igor D. Karachentsev, Gagandeep S. Anand, Maksim I. Chazov, Serafim S. Kaisan, Ehsan Kourkchi, Lidia N. Makarova et al.

KKR 18 is a dwarf irregular galaxy in the Local Void at a distance of 9.46 Mpc. It is gas rich and was experiencing vigorous star formation 20 - 100 Myr ago. Its metallicity is 4% of Solar from an emission spectrum, qualifying is as extremely metal poor (XMP). Its most remarkable characteristic is an extremely deficient Red Giant Branch. This feature is shared with a small number of other dwarf galaxies and it is inferred that they lack ancient stellar components. It is suggested that these are…

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astro-ph.GA

Linking orbital history to the quenching of isolated dwarf galaxies

Sophia Um, Devontae C. Baxter, Ethan O. Nadler

Recent discoveries of isolated dwarf galaxies (${M}_{\star}\sim 10^{7-9}~{\rm M}_{\odot}$) with no signs of ongoing star formation have challenged the prevailing notion that these solitary systems are exclusively star-forming. Investigating the origins of isolated quenched dwarfs provides important clues into the dominant processes driving galaxy quenching as a function of environment and stellar mass. In this study, we identify central dwarf galaxies in the Illustris-TNG50 cosmological simulati…

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astro-ph.GA

Hint of bimodal Mg-Al anticorrelation in the metal-poor Globular Cluster NGC 4372

Camila Beltrand, Macarena Uribe, Sandro Villanova, César Muñoz

We present a detailed chemical abundance analysis of seven red giant branch stars in the very metal-poor globular cluster NGC~4372, based on high-resolution UVES spectra. Our study aims to characterize the chemical evolution of NGC~4372 and investigate the presence of multiple populations. We derived abundances for 17 elements, including light, iron-peak, $α$, and heavy elements, using both equivalent width and spectral synthesis methods. We find a mean cluster metallicity of [Fe/H]=$-$2.36 $\pm…

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astro-ph.GA

Extending the Stellar-to-Halo Mass Relation to Dwarf Galaxies with DESI DR1

Z. Shao, Y. Zu, A. Salcedo, Y. Lin, Z. Chen, X. Xu, J. Hua, Z. Zhai et al.

Constraining the dark matter halos of the smallest galaxies offers fundamental insights into the nature of dark matter and stellar feedback. Using the Dark Energy Spectroscopic Instrument (DESI) Data Release 1, we infer the stellar-to-halo mass relation (SHMR) down to the dwarf scale ($M_\star < 10^9\,M_\odot$), without extrapolation from the higher mass range. Leveraging the unprecedented depth of the DESI Bright Galaxy Survey at $0.01 < z < 0.2$, we construct 12 samples spanning nearly four or…

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astro-ph.GAastro-ph.CO

H I Absorbers as Beacons of Hidden Structure at $z \sim 3$: Multi-Component, Metal-Rich Absorption System near a Protocluster

Kentaro Koretomo, Nobunari Kashikawa, Toru Misawa, Jun Toshikawa, Yoshihiro Takeda, Hisakazu Uchiyama, Junya Arita, Shunta Shimizu et al.

H I gas traces the large-scale structure and provides the primary fuel for star formation. High-$z$ protoclusters are ideal laboratories to study how H I gas is accreted and consumed during the formation of the most massive structures in the Universe. However, much remains unknown about the distribution and physical state of their H I gas. We examine a rare configuration in which a protocluster candidate is located in front of a quasar at $z=3.09$. Our spectroscopic campaign confirms a protoclus…

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gr-qcastro-ph.HE

Waveform models for the gravitational-wave memory effect: III. Phenomenological frequency-domain model for nonspinning binaries

Arwa Elhashash, David A. Nichols

We present a phenomenological frequency-domain model for the gravitational-wave (GW) memory signal from nonspinning binary-black-hole mergers on quasicircular orbits. We develop separate amplitude and phase models for the dominant $(l,m)=(2,0)$ spherical-harmonic mode of the GW memory signal. The amplitude and phase models are built from superpositions of elementary and transcendental functions, which can be evaluated efficiently. Both portions of the model are calibrated against a numerical-rel…

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astro-ph.GAastro-ph.CO

Widespread Inflows Reveal Baryonic Cycling in Star-forming and Quiescent Galaxies

Hassen M. Yesuf, Ravi Joshi, Yuxuan Zou, Feng Yuan, Luis C. Ho, Lin Lin, Lei Hao, Shiyin Shen et al.

Cool-gas inflows, required to sustain star formation, have been fundamental in simulations yet remained observationally elusive. Using DESI spectroscopy of ~30,000 galaxies, we identify coherent inflowing gas (~100 km/s) in 20-50% of the sample, yielding a population-level census of gas flows. We uncover a striking inversion: inflows are detected in quiescent galaxies, whereas star-forming systems are dominated by gravitationally bound outflows. At fixed age, galaxies with inflows, outflows, or…

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astro-ph.GA

Recovering Ionizing Photon Escape and Galaxy Scaling Relations in the LzLCS via Si II and C II Absorption Lines and Mock Spectra from a Radiation-Hydrodynamic Simulation

John Trevino, Simon Gazagnes, Danielle A. Berg, Kaelee S. Parker, Valentin Mauerhofer, Jeremy Blaizot, Anne Verhamme, Sophia R. Flury et al.

In this work, we use a radiation-hydrodynamic simulation of a single $\sim10^9M_{\odot}$ virtual galaxy to study Si II and C II line profiles seen in stacked HST/COS spectra of 58 galaxies from the LzLCS+ sample. We compare stacks across three mass bins ($M_{\star} \leq 10^8M_{\odot}$, $10^8$-$10^9M_{\odot}$, and $M_{\star} \geq 10^9M_{\odot}$) and three stacking methods (mean, median, and weighted average) to a library of 22,500 mock spectra. We investigate whether the simulation can accurately…

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astro-ph.SR

Improvements to Asteroseismic Fitting of White Dwarfs in the Gaia Era

Andrew H. Dublin, Keaton J. Bell, Agnès Bischoff-Kim

White dwarf asteroseismology aims to constrain the interior structures of pulsating white dwarf stars by fitting observed pulsation periods to those computed for stellar models. However, there remain several obstacles for achieving reliable results with the model grid-fitting approach. We simulate data for a parameter recovery experiment in one and two dimensions (mass and effective temperature) to demonstrate improved methodologies that address challenges for characterizing degenerate asterosei…

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astro-ph.GAastro-ph.HE

AGN-DB: A Unified Multi-Wavelength Database of Active Galactic Nuclei

Alessandro Peca, Nico Cappelluti, C. Megan Urry, Zhongtian Hu, Jerry R. Bonnell, Jack McKeown, Giulia Cerini, Xulei Sun et al.

We present the Active Galactic Nuclei Database (AGN-DB), a comprehensive, multi-wavelength catalog compiled from more than 100 publicly available AGN catalogs and samples released by the end of 2025, spanning radio to $γ$-ray wavelengths. The database contains approximately 8.1 million unique sources, approximately 7.8 million of which remain after flagging stellar contaminants, and approximately 6.8 million of these are classified as AGN. Source cross-matching across catalogs is performed using…

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astro-ph.EP

Composition gradients in sub-Neptunes: K2-18 b and TOI-270 d as case studies

Luca Morf, Ravit Helled

Structure models of sub-Neptunes commonly assume purely adiabatic interiors with distinct layers of homogeneous composition. We assess how allowing for more complex interiors with composition gradients affects the inferred internal structure and bulk compositions of the sub-Neptunes K2-18 b and TOI-270 d. We compare purely adiabatic models with distinct layers against models that include composition gradients and stable non-convective regions. We present solutions that are consistent with the ob…

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astro-ph.GA

Resolved Dust-Gas-Metallicity relations in nearby spiral galaxies

Vidhi Tailor, Viviana Casasola, Francesco Calura, Francesca Pozzi, Jacopo Fritz, Maritza Lara-López, Marco Palla, Simone Bianchi et al.

Context: Understanding the interstellar medium (ISM) requires high-resolution, multi-component mapping to capture its complex physical structure. Nearby spiral galaxies, with their abundant and diverse ISM, provide an ideal laboratory for such a comprehensive analysis at sub-galactic scales. Aims: We investigate dust-to-gas (DGR) and dust-to-metal (DMR) ratios as a functions of gas-phase metallicity (Z), on spatial scales ranging from 0.6 to 2.3 kpc, in a sample of 10 nearby spiral galaxies, spa…

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astro-ph.HEastro-ph.GA

A Kinematic Measurement of the Effective Viscosity of the Intracluster Medium: The Cold Front of A3667 Seen by XRISM

Yutaka Fujita, Yuki Omiya

Constraints on the effective viscosity of the intracluster medium (ICM) come almost exclusively from imaging: the power spectrum of X-ray surface brightness fluctuations, and the morphology of Kelvin-Helmholtz rolls at cold fronts. Both indicate a viscosity below the isotropic Spitzer value. XRISM/Resolve opens a complementary, purely kinematic route, in which the viscosity is inferred from the thickness of the viscous shear layer that develops at a sliding contact discontinuity. We apply it to…

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astro-ph.GAastro-ph.HE

Super-Eddington Accretion and Early-Stage Feedback in Ton S180

Pierpaolo Condò, Giacomo Venturi, Eleonora Parlanti, Marco Berton, Enrico Congiu, Alessia Tortosa, Stefano Carniani, Francesco Tombesi et al.

Narrow-line Seyfert 1 (NLSy1) galaxies are key laboratories for studying rapid supermassive black hole (SMBH) growth and active galactic nucleus (AGN) feedback at high accretion rates. We investigate the nearby NLSy1 Ton S180 with VLT-MUSE optical integral field spectroscopy to connect its nuclear accretion properties with the spatially resolved ionized gas and host-galaxy kinematics. We modeled the unresolved nuclear spectrum and applied a custom point spread function subtraction to recover the…

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astro-ph.IMastro-ph.CO

ALPACA I: Controlling source and PSF systematics in JWST time-delay cosmography with differentiable lens modeling

Hrvoje Krizic, Martin Millon, Aymeric Galan, Sydney Erickson, Phil Marshall

Time-delay cosmography provides an independent probe of the Hubble constant ($H_0$), but exploiting the high-resolution imaging of the James Webb Space Telescope (JWST) requires strong-lens models that capture complex source-galaxy morphologies and the point spread function (PSF) with high fidelity. Flexible source and joint PSF reconstruction are computationally expensive, motivating more rigid parameterizations that can bias the inferred time-delay distance $D_{Δt}$. We present ALPACA, a semi-…

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astro-ph.GA

JWST/NIRSpec Reveals Diverse Nuclear Environments in Dwarf Galaxies Hosting AGN

Thomas Bohn, Archana Aravindan, Gabriela Canalizo, Aditya Togi, Shobita Satyapal, Tohru Nagao, Matthew Malkan, Thomas S. Y. Lai et al.

Dwarf galaxies, in the $Λ$CDM framework, are expected to dominate the galaxy number density at all redshifts. As such, studying AGN in these systems, including characterizing their local environments and emission properties, is essential in obtaining a comprehensive view of the AGN population and their influence on their host galaxy. To this end, we present JWST/NIRSpec IFU observations of four dwarf galaxies (M$_\star<$10$^{9.5}\;$M$_\odot$) with evidence of AGN activity. Utilizing the improvem…

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