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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GA

Ripples in the OCEANS: Broad Line Variability of Little Red Dots

Madisyn Brooks, Kelcey Davis, Jonathan R. Trump, Raymond C. Simons, Erini Lambrides, Pablo Arrabal Haro, Bren E. Backhaus, Nikko J. Cleri et al.

Little Red Dots (LRDs) are a unique class of compact, red sources discovered in the JWST extragalactic deep fields. Determining if they are indeed powered by accreting supermassive black holes (SMBHs) is one of the main drivers of the intense study of these objects. Evidence for variability in these objects provides a direct test for the active galactic nucleus (AGN) nature of their central engine. In this study, we present a variability analysis of 6 LRDs observed by the $R \sim 2700$ OCEANS su…

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astro-ph.GA

CLASSY. XV. Kinematics and Spatial Distributions of Outflows in Local Highly Star-Forming Galaxies

Mason S. Huberty, Cody A. Carr, Claudia Scarlata, Alaina Henry, Matthew Hayes, Xinfeng Xu, Timothy Heckman, Karla Z. Arellano-Cordova et al.

Star-forming galaxies drive massive outflows that play an important role in galaxy evolution by regulating feedback and influencing the dynamics of surrounding media. Measuring galactic outflow rates is essential for quantifying feedback efficiency and the amount of mass, momentum, and energy deposited into the circumgalactic medium. In this paper, we examine 17 galactic outflows from the CLASSY survey with radiative transfer modeling of UV absorption lines presented in M. Huberty et al. (2024),…

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astro-ph.SR

Astronomical Cardiology II: A Search For Heartbeat Stars Using APOGEE and TESS

Jowen Callahan, D. M. Rowan, C. S. Kochanek, M. M. Fausnaugh

Stellar binaries in short-period, highly eccentric systems with significant tidal deformations near pericenter, also known as heartbeat stars, are a laboratory for studying dynamical tides and oscillations in stars. We identify 50 heartbeat stars using TESS light curves of stars identified as binaries using SDSS APOGEE. We fit their phase-folded TESS light curves with an analytic model to measure their orbital periods, eccentricities, inclinations, and arguments of periastron. We measure the mas…

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astro-ph.GA

Trace the Self-Gravitating Gas Using CO Isotopologues

Linjing Feng, Jingwen Wu, Sihan Jiao, Zhi-Yu Zhang, Junzhi Wang, Chao-Wei Tsai, Di Li, Hauyu Baobab Liu et al.

Recent studies have shown that the star formation rate (SFR) correlates tightly and linearly with the mass of gravitationally bound gas, which can be delineated from the power-law tail of the column-density probability distribution function ($N$-PDF) derived from dust emission observations. This relationship holds across four orders of magnitude within the Milky Way--spanning low-mass to high-mass star-forming regions and encompassing the extreme environment of the Central Molecular Zone. Buildi…

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astro-ph.GA

FLAGS II: Constraining Galaxy Formation Models with Dimensionality Reduction of Direct Observables

Jack C. Turner, Stephen M. Wilkins, William J. Roper, Aswin P. Vijayan

Comparisons between observations of galaxies and theoretical predictions are regularly performed using physical properties, which are inferred by the often slow and biased process of SED fitting. Forward modelling facilitates a reliable alternative, whereby models are evaluated using direct observables alone. However, these datasets become high-dimensional when collating observations from multiple telescopes, leading to sparse sampling, memory intensity and visualisation difficulties. We show th…

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astro-ph.IMstat.ML

Don't Cut Corners: How Training Outside the Prior Makes Simulation-Based Inference More Robust

Chaipat Tirapongprasert, Matthew Ho

Large astrophysical simulation campaigns often generate training data by sampling parameters across a Uniform prior box. Due to the proposal's sharp edge, neural posterior estimators struggle to learn accurate approximations near the boundaries. We propose Tailed-Uniform, a family of hybrid proposal distributions for sampling training simulations for robust simulation-based inference. By padding the original hard-truncated training box with decaying tails, Tailed-Uniform-trained networks yield m…

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astro-ph.GA

Why is GN-z11 Bright, Compact, and Nitrogen Enhanced? Insights from UV Absorption and Emission Diagnostics

Minami Nakane, Masami Ouchi

We investigate the UV spectrum of GN-z11, a luminous, compact galaxy with strong nitrogen lines, at $z=10.60$, using deep JWST/NIRSpec high-resolution IFU and medium-resolution MSA spectra assembled from the JADES, SPURS, and GO programs. After optimized reduction and extraction of the IFU data including an evaluation of statistical and systematic uncertainties, we obtain mutually consistent spectra from the high- and medium-resolution observations. After carefully accounting for the data qualit…

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astro-ph.HE

Interacting Supernovae: a Radio and X-ray Strategy to Constrain the Structure of the Circumstellar Medium

Shunke Ai, Irene Tamborra, Leonardo Dinoi

The interaction of supernova (SN) ejecta with the dense circumstellar medium (CSM) converts shock kinetic energy into radiation across multiple wavebands. We investigate the dependence of the X-ray and radio emission on the CSM geometry, considering spherical, hourglass, and disk shapes for the CSM. We find that the spectral and light-curve properties, both in X-ray and radio, significantly differ for spherical and non-spherical CSM structures. For a non-spherical CSM, the radio light curve flat…

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astro-ph.GA

Why is GN-z11 Bright, Compact, and Nitrogen Enhanced? Insights from UV Absorption and Emission Diagnostics

Minami Nakane, Masami Ouchi

We investigate the UV spectrum of GN-z11, a luminous, compact galaxy with strong nitrogen lines, at $z=10.60$, using deep JWST/NIRSpec high-resolution IFU and medium-resolution MSA spectra assembled from the JADES, SPURS, and GO programs. After optimized reduction and extraction of the IFU data including an evaluation of statistical and systematic uncertainties, we obtain mutually consistent spectra from the high- and medium-resolution observations. After carefully accounting for the data qualit…

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astro-ph.GA

Recycled Gas Dominates the Metal-rich Fuel of Supermassive Black Holes

Dongyun Kwak, Ena Choi, Hannah Jhee, Rachel S. Somerville, Thorsten Naab, Michaela Hirschmann, Jaejin Shin, Jong-Hak Woo et al.

Understanding the origin and chemical properties of gas accreted by supermassive black holes (SMBHs) is essential for linking black hole growth to galaxy evolution. Using a suite of 30 high-resolution cosmological zoom-in simulations, we investigate the chemical properties of gas accreted onto SMBHs in massive galaxies with stellar masses of $10^{10.9-11.9}\,\rm M_\odot$ and black hole masses of $10^{8.5-9.7}\,\rm M_\odot$ at $z=0$. By tracing the full cosmological histories of individual gas pa…

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astro-ph.GA

The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. V. When Galaxies Glow with Industry

Olivia Curtis, Aidan J. Rowland, Jason T. Wright, Caryl Gronwall, Jakob M. Helton, Joel Leja

We present the most robust stellar population synthesis (SPS)-based search for galaxy-spanning technological waste heat to date, applied to 129 nearby galaxies spanning a wide range of spectral energy distribution (SED) types, including ultraluminous IR galaxies and MIR-luminous active galactic nuclei (AGN). We incorporate the AGENT Dyson sphere formalism into the Flexible Stellar Population Synthesis code at the stellar population level, so nebular and dust emission respond self-consistently to…

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astro-ph.EP

Climates of Gl 514 b

Héctor E. Delgado Díaz, Rory Barnes, Russell Deitrick, Mario Damasso, Nathaniel Brown

The continuous discovery of exoplanets, each with distinctive stellar and planetary properties, along with the development of higher resolution ground and space telescopes has positioned climate evolution as a fundamental component of the study of habitability. In particular, the planet Gl 514 b, located within the habitable zone of an M0.5 dwarf star 7.62 pc from Earth, is a candidate for direct observations with future ground and space-based telescopes and therefore worthy of climate modeling.…

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astro-ph.GA

From Cluster Cores to the Low-Density Field: Strong Environmental Quenching of Galaxy Star Formation at Low Redshift

Mohamed H. Abdullah, A. E. Abdelaziz, Gillian Wilson, Ahmed M. Abdelbar, M. M. Beheary, Y. H. M. Hendy

We investigate how galaxy star formation activity depends on environment using a sample of 81,647 SDSS galaxies selected over $0.03\leq z\leq0.075$ and $9.7\leq\log_{10}(M_\star/h^{-2}M_\odot)\leq11.0$, including 18,426 members from 572 clusters in the \texttt{GalWCat19} catalog. We characterize environment in two complementary ways: (1) nearest-neighbor density for the full sample, and (2) clustercentric radius and host halo mass for \texttt{GalWCat19}. The sSFR distribution remains bimodal acr…

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astro-ph.GA

CHANG-ES XL: Magnetic Field Structures in the Disk and Halo of NGC 891

N. Pourjafari, J. M. Stil, R. -J. Dettmar, P. Kamphuis, R. Beck, J. English, V. Heesen, J. Irwin et al.

We present new Karl G. Jansky Very Large Array S-band (2-4 GHz) observations of the edge-on spiral galaxy NGC 891, complemented by C-band data, to investigate the structure of its radio continuum halo. Using rotation measure synthesis we detected an extended polarized halo, with most spatially extended polarized emission confined to Faraday depths within +/- 150 rad m-2. We identified a localized region in the north-east side of the galaxy that shows an enhancement in polarized intensity (not in…

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astro-ph.SR

Hemispheric Asymmetry of Solar Active Regions Arises from a Nested Population

Aimee A. Norton

We investigate the longitude--time distribution of NOAA active regions (ARs) during Solar Cycles 22--24 and find statistically significant North--South asymmetry in AR emergence. Using an activity-nest identification algorithm, we show that this asymmetry is concentrated in the subset of ARs that participate in nests. Nest-member ARs exhibit substantially larger hemispheric asymmetry than either the full AR population or the non-nest population, and the asymmetry is largely removed when nest-mem…

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astro-ph.SR

Hemispheric Asymmetry of Solar Active Regions Arises from a Nested Population

Aimee A. Norton

We investigate the longitude--time distribution of NOAA active regions (ARs) during Solar Cycles 22--24 and find statistically significant North--South asymmetry in AR emergence. Using an activity-nest identification algorithm, we show that this asymmetry is concentrated in the subset of ARs that participate in nests. Nest-member ARs exhibit substantially larger hemispheric asymmetry than either the full AR population or the non-nest population, and the asymmetry is largely removed when nest-mem…

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astro-ph.GA

The Delay Time Distribution of Quasi-Periodic Eruptions

Margaret Shepherd, K. Decker French, Jason T. Hinkle, Ferdinand, Samaresh Mondal, Yashasvi Moon, Margaret E. Verrico

Quasi-periodic eruptions (QPEs) are quasi-periodic X-ray bursts observed in the nucleus of a galaxy. Multiple pieces of observational evidence link QPEs to tidal disruption events (TDEs), which occur when stars are disrupted after approaching a supermassive black hole too closely. Post-starburst galaxies are overrepresented among the host galaxies of both TDEs and QPEs, though the mechanism causing this overrepresentation is unknown. While their physical origin is unclear, the delay time distrib…

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astro-ph.GA

A systematic comparison of green valley selection criteria across multiparameter spaces using a homogeneous ultraviolet-optical dataset

Pius Privatus, Umananda Dev Goswami

We present a systematic comparison of commonly adopted green valley (GV) selection criteria by examining their distributions across multiple observational and physical parameter spaces. Using a homogeneous ultraviolet-optical dataset constructed from the Galaxy Evolution Explorer (GALEX) and the Sloan Digital Sky Survey (SDSS), we construct GV samples based on rest-frame $u-r$ and NUV$-r$ colours, specific star formation rate, and the $D_n(4000)$ spectral index. These samples are analysed in col…

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astro-ph.GAastro-ph.CO

Evidence for the First Globular Cluster Stellar Stream beyond the Milky Way

Julie Kiel Holm, Sarah Pearson, Jacob Nibauer, David J. Sand, Adrian M. Price-Whelan, Tjitske Starkenburg, David Hendel, Catherine Fielder et al.

The dark matter content of ultra-diffuse galaxies is the subject of considerable debate. Stellar streams, which form when a host galaxy tidally strips stars from an orbiting stellar system, provide a powerful technique to constrain the dark matter content of external galaxies. The stripped stars form long, thin leading and trailing tidal arms that persist for billions of years. Stellar streams from globular clusters are particularly sensitive probes of dark matter halos and substructure. Globula…

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astro-ph.HE

High-energy neutrino signatures of embedded GRB jets in AGN disks: a dynamic jet-propagation framework

Wei-Cheng Long, Yun-Wei Yu

Relativistic jets embedded in active galactic nucleus (AGN) accretion disks are promising high-energy neutrino sources, but their emission is often estimated from a single representative jet state. We develop a time-dependent framework that follows jet-head propagation, evolving reverse-shock conditions, and particle cooling until the jet chokes or breaks out, and apply it to the SG and TQM disk models. For the representative choked cases, neutrino emission is dominated by the high-dissipation p…

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astro-ph.IMgr-qc

LIGO Detector Characterization in the Second and Third Parts of the Fourth Observing Run

J. Glanzer, A. F. Helmling-Cornell, A. Calafat, S. R. Callos, E. Capote, A. Effler, T. A. Ferreira, E. Goetz et al.

LIGO detector characterization efforts enabled the confident detection of gravitational waves from hundreds of compact binary coalescences during the fourth observing run. Reliable production of high quality detector data and rapid noise mitigation efforts allow the extraction of the most in-depth knowledge of gravitational wave sources and their progenitors. In this paper we describe LIGO detector characterization activities during the second and third parts of O4-O4b and O4c. We summarize chan…

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astro-ph.SRastro-ph.GA

Nascent Embedded-protostar Survey in Taurus (NEST) I: Protostellar Multiplicity

Aislinn C. Plante, John J. Tobin, Patrick D. Sheehan, Noshin Yesmin, Nicholas P. Ballering, Tyler L. Bourke, Josh Eisner, Zhi-Yun Li et al.

We present new ALMA 0.9 mm and VLA 9 mm observations in the Taurus Molecular Cloud (TMC) of 25 protostellar systems, containing 40 protostars, observed at 0.3" (~20 au) resolution. Within separations of 18-10,000 au, the ALMA/VLA-observed Taurus sample has a multiplicity fraction (MF), defined as the fraction of systems with at least one companion, of 0.50 +/- 0.07, and a companion fraction (CF), defined as the average number of companions per system, of 0.58 +/- 0.20. To build a more complete c…

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astro-ph.HE

Impact of Neutrino Flavour Conversion on the Diffuse Neutrino Background from Neutrino-dominated Accretion Flows

Yun-Feng Wei, Tong Liu

Neutrino-dominated accretion flows (NDAFs) are believed to form during the fallback accretion phase of some core-collapse supernovae (CCSNe). Such systems produce copious neutrino emission, whose cumulative contribution over cosmic history forms the diffuse NDAF neutrino background (DNNB). As neutrinos propagate from the source to Earth, flavour conversion can significantly modify the observed neutrino spectra and consequently the detectability of the DNNB. In this work, based on fallback CCSN s…

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astro-ph.GAastro-ph.IM

The Shape of the Vertical Action Distribution Locates the Scatterers that Heat the Galactic Disc

Yuan-Sen Ting, Hans-Walter Rix

The Milky Way's stellar disc is thicker than the cold gas layer from which its stars form. What scatters stars onto orbits with greater vertical motion remains unresolved. Scatterers could fill the disc volume, as bending waves or dark substructure would, or could be confined to the midplane, as giant molecular clouds are. Scattering from a midplane layer occurs only during the fast plane-crossing phase and becomes less effective as that speed increases, whereas a volume-filling perturbation rem…

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astro-ph.IMastro-ph.SR

Voltage-to-temperature calibration of the High Altitude THz Solar telescope acquisition system

Gedeane G. S. Kenshima, Daniel R. Sousa, Tiago Giorgetti, Paulo J. A. Simões, C. Guillermo Giménez de Castro

The THz range has been under-explored for solar astronomy, mainly due to technological limitations. Only recently, a few new telescopes, such as the High Altitude Terahertz Solar (HATS) photometer, have been monitoring the solar activity in this range of the spectrum. This paper presents the experimental characterization and voltage-to-temperature calibration of the HATS acquisition system. HATS uses a Golay cell for capturing the incoming radiation, modulated by a 20 Hz fork chopper. The amplit…

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astro-ph.GA

The effect of galaxy interactions on star formation rates in the COLIBRE simulations

Quinten W. E. van Zegveld, Evgenii Chaikin, Joop Schaye, David R. Patton, Sara L. Ellison, Alejandro Benítez-Llambay, Filip Huško, Robert J. McGibbon et al.

Observations and theory indicate that galaxy interactions enhance star formation rates (SFRs). However, the degree of enhancement and its dependence on the properties of the interacting galaxies vary across different studies. In this work, we use the COLIBRE simulations of galaxy formation to investigate the effect of interactions on the SFRs of star-forming galaxies at redshift $z\approx0$. The COLIBRE simulations capture the multiphase nature of the interstellar medium and have volumes up to $…

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astro-ph.COastro-ph.GA

CIBER $\times$ galaxy cross-correlations reveal a bright, low-redshift NIR background

Richard M. Feder, Grigory Heaton, James J. Bock, Yun-Ting Cheng, Yi-Kuan Chiang, Phillip M. Korngut, Shuji Matsuura, Jordan Mirocha et al.

We perform the first tomographic analysis of near-IR extragalactic background light (EBL) anisotropies, cross-correlating CIBER 1.1 and 1.8 $μ$m imager data with photometric galaxy catalogs from DESI Legacy Survey DR8 and Hyper-Suprime-Cam Ultra-Deep Survey. We measure significantly higher cross-power than expectations from an integrated galaxy light (IGL) model on scales $\ell < 2000$, concentrated at low redshift ($z\lesssim 0.6$). Cluster member galaxies and associated structure account for 1…

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astro-ph.IM

Updates to WFC3/UVIS Encircled Energy Values in Select Filters

Anne O'Connor, Jennifer Mack, Varun Bajaj

We present updated encircled energy (EE) curves for a subset of UVIS filters. These are derived from a reanalysis of the drizzled Point Spread Function (PSF) data underlying the current EE calibration together with new measurements from deep observations of the PSF wings. Improved centroiding and analysis techniques applied to the drizzled PSFs produce more accurate EE values at small radii ($r \le 10$ pixels), bringing the results into closer agreement with a large archival PSF study (Huynh et…

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nucl-thastro-ph.HEhep-ph

Transport properties in binary neutron star mergers: Effect of magnetic field

Pranjal Tambe, Debarati Chatterjee

In extreme environments such as binary neutron star mergers, temperatures as high as $50$ MeV and magnetic fields up to $10^{17}$ G, reach a regime where neutrino transport governs the macroscopic thermodynamic and chemical evolution. Existing merger simulations rely on zero magnetic field neutrino emissivity and opacity, potentially missing critical transport physics in highly magnetized neutron star cores. We present an exact framework for computing charged current Urca emissivity and neutrino…

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astro-ph.IM

Automation and Modernisation of Legacy BiSON Solar Observatories with the BiSON:NG Platform

S. J. Hale, E. Murray, W. J. Chaplin, Y. P. Elsworth, R. Howe, P. L. Pallé, E. J. Rhodes

The Birmingham Solar Oscillations Network (BiSON) provides long-term, high-precision Sun-as-a-star radial-velocity observations for helioseismology. While most BiSON sites operate autonomously, two observatories at Observatorio del Teide, Tenerife, and at Mount Wilson Observatory, USA, have historically required daily on-site operation. We present the automation of these sites using the BiSON:NG next-generation observing platform, incorporating compact fibre-fed instrumentation and a modular, mi…

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