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Research Trends

Latest preprints in space engineering and astrophysics.

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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astro-ph.GA

Search for a Globular Cluster whose Passage through the Galactic Disk could Trigger the Radcliffe Wave

V. V. Bobylev, A. T. Bajkova

Using a catalog of 152 globular clusters (GCs), their orbits were constructed to determine their intersections with the Galaxy's plane of symmetry. Young open star clusters (OSCs) were selected from the selection zone characteristic of the Radcliffe wave. The Hunt and Reffert catalog served as the source of data on these OSCs. A grouping of 17 OSCs with an average age of 32.7 million years was found. It is compact in coordinate, velocity, and age space. This grouping is shown to be a good candid…

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astro-ph.HEastro-ph.GA

Constraining the gamma-ray efficiency of LINER outflows with Fermi-LAT and MEGARA

Alberto Domínguez, Alejandra León, Adithiya Dinesh, Armando Gil de Paz

Low-Ionization Nuclear Emission-line Regions (LINERs) commonly host ionized gas outflows, but their role as high-energy particle accelerators remains debated, particularly following the very-high-energy $γ$-ray detection of NGC 4278, which implied extreme radiative efficiencies. We empirically determine the $γ$-ray radiative efficiency of a local sample of LINERs to test whether their high-energy emission can be powered by extended ionized outflows or requires compact nuclear jets. We combine sp…

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physics.plasm-phastro-ph.SRcond-mat.stat-mech

The Ambipolar electric field in multispecies plasma atmospheres: effects of alpha particles and stochastic heating

Luca Barbieri, Pascal Démoulin, Daniel Verscharen

We investigate stationary states of a collisionless, gravitationally stratified plasma atmosphere composed of electrons, protons, and alpha particles by extending Pannekoek--Rosseland theory to multispecies and multi-temperature plasmas. Starting from Liouville's theorem, we derive the self-consistent ambipolar electric field from kinetic equilibrium and charge neutrality. For a single-temperature atmosphere, we obtain analytical expressions for the ambipolar field, show its dependence on alpha-…

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astro-ph.HE

Identification of a Large-Scale Diffuse Gamma-Ray Structure in the Southern Galactic Hemisphere

Zhen Xie, Xiaoyuan Huang, Bing Liu, Ruizhi Yang

We identify and characterize a large-scale diffuse gamma-ray structure in the Southern Galactic Hemisphere using 17 yr of Fermi-LAT data. An energy-dependent likelihood analysis, including alternative Galactic diffuse-emission models, isotropic emission, the Fermi bubbles, and resolved 4FGL sources, reveals an extended excess that persists across the tested background models and spans tens of degrees. The excess broadly follows the X-ray-defined southern eROSITA Bubble (eB) region, while also ov…

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astro-ph.EP

Evolutionary tracks of giant planets formed by disk instability

Mirco Bussmann, Ravit Helled

The evolution of giant planets depends on their formation history. While several evolutionary models self-consistently link planet formation by core accretion to long-term evolution, such models for planets formed by disk instability are lacking. We simulate the evolution of giant planets formed by disk instability and follow their evolution including the pre-collapse phase, dynamical collapse, and long-term contraction in a unified numerical framework. The evolution is simulated using the MESPA…

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astro-ph.SR

Deep MUSE observations of SNR 0509-67.5 reveal a double degenerate merger progenitor

Priyam Das, Ivo R. Seitenzahl, Gilles Ferrand, Rudiger Pakmor, Simon J. Murphy, Ashley Ruiter, Brian P. Schmidt, Friedrich K. Roepke et al.

Deep MUSE observations of SNR 0509-67.5 reveal that the coronal [Fe\,\textsc{xiv}] $\mathrmλ$5303 emission line appears with either one or two velocity components across the entire remnant, arising from reverse-shocked ejecta moving toward and away from the observer. A supervised dense neural network classifies each spaxel and fits Gaussian profiles plus a linear function to the observed line emission. We measure a bulk Doppler velocity of $-1000\pm60~~\mathrm{km~s^{-1}}$, interpreted as the lin…

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astro-ph.HEastro-ph.GAmath-phphysics.comp-ph

Spiral structure from the interference of gravitational eigenmodes in ultralight dark matter halos

Jacob Reinach, Hubert Bray

We use a variety of analytic and numerical techniques to approximate the geometry of individual dark matter halos when modeled as collections of ultralight scalar bosons (ULDM), followed by an analysis on the future directions and implications of this work. Ultimately, we aim to understand the morphology and creation of complex structures (like spirals) in galaxies from a geometric standpoint and to investigate the connection between dark matter and baryonic matter in galaxies. We find that supe…

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astro-ph.HE

Discovery of 27 new Rotating Radio Transients by MeerTRAP

S. Singh, J. Tian, B. W. Stappers, K. Shaji, K. M. Rajwade, L. Levin, J. D. Turner, M. C. Bezuidenhout et al.

We present the discovery of 27 new Galactic transients made by the commensal MeerTRAP single pulse search programme at the MeerKAT telescope. We determine the location of 14 of these discoveries with arcsecond accuracy by imaging the data captured in the dedicated transient buffer. A preliminary estimate of the period was made for 8 sources using the arrival times of several pulses detected by MeerTRAP. The periods of these transients range between 0.78 s and 4 s. For the previously published Me…

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astro-ph.SR

New constraints on the binary system HD 327083 and its gaseous and dusty environments

L. Cidale, P. Marchiano, M. Kraus, I. Andruchow, M. L. Arias, M. Cure, M. Borges Fernandes, Y. Aidelman et al.

Binary systems with circumbinary molecular and dust rings are of great interest because they provide insights into the dynamics and evolution of stellar systems and the chemistry of the surrounding material. We aim to elucidate the nature of the B[e] binary system HD 327083 and the physical properties of its circumstellar and circumbinary envelopes. We combined multi-epoch high-spectral resolution optical and near-IR observations with VLTI/MIDI observations and ASAS-3 photometry. The data were a…

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astro-ph.SRastro-ph.HE

Chemical fingerprints of binary mass transfer in massive stars

Harim Jin, Norbert Langer

The majority of massive stars are born in close binary systems. As stars expand when they age, mass transfer or even a merger with their companion is inevitable. However, most binary interaction products appear as single stars, such that the main evidence of their exciting past is lost. In a comprehensive grid of detailed massive binary evolution models we find systematic trends in chemical surface abundances that allow identifying the past mass gainers. We develop an analytic framework which is…

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astro-ph.GA

Classifying Quasar Types Without a Spectrum

Adrien Hélias, Pauline Barmby, Sarah C. Gallagher, Shahram Abbassi, Matthew J. Graham

Distinguishing between Type 1 and Type 2 quasars is important because it helps us understand accretion regimes, black hole mass scaling, disk instabilities and feedback processes in active galaxies. Although spectroscopy provides robust classification, it does not scale well with the millions of quasars observed in modern surveys, as it requires substantial time and resources to acquire a good spectrum. On the photometry side, quasar light curves are always irregularly sampled and affected by th…

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astro-ph.SR

1.5D investigation of the Hanle effect in the Ca I 4227 line using partial frequency redistribution. Comparison of synthetic Stokes profiles in Bifrost and MURaM-ChE rMHD models

Devang Agnihotri, L. S. Anusha, D. Przybylski, R. H. Cameron, S. K. Solanki

Modeling scattering polarization in the Ca I 4227 Å line is important for diagnosing chromospheric magnetic fields. We investigate the relative influence of formation heights and magnetic fields, through the Hanle effect, on spatially averaged synthetic Stokes profiles using realistic solar atmospheres. We employ 1D vertical columns from 3D radiative magnetohydrodynamic simulations of the solar chromosphere performed with the Bifrost and MURaM-ChE codes, and solve the 1.5D non-local thermodynami…

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