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Research Trends

Latest preprints in space engineering and astrophysics.

hep-phastro-ph.HEhep-th

Radion/Dilaton portal freeze-in dark matter in extra-dimensional theories

Amrita Mukherjee, George Sanamyan, Dipan Sengupta

We perform a comprehensive analysis of a radion/dilaton portal freeze-in dark matter in models of stabilized warped extra-dimensions. We show that the relic abundance of a generic dark matter particle (scalars, vectors, or fermions) is obtained via the conformal coupling of the radial mode in a consistent model stabilized warped extra- dimensions; our calculations show that in scenarios where the reheating temperature is much smaller than the radion mass, keV-TeV scale dark matter particles can…

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astro-ph.GA

Barflow: Modeling Gas Kinematics of Bar-Driven Flows

Seungwon Baek, Woong-Tae Kim, Taehyun Kim, Dajeong Jang, SungWon Kwak

We present self-consistent $N$-body/hydrodynamical simulations of isolated, Milky Way-like galaxies with stellar and gaseous disks. By varying the initial gas fraction, we find that gas delays bar formation and, in the most gas-rich model, suppresses it by exciting higher-order spiral modes and promoting early central mass growth. Once a bar forms, continued gas inflow and gravitational torques weaken the bar and inhibit its secular slowdown, keeping bars in the gas-bearing models shorter and pr…

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astro-ph.IM

Optimal Design of Shaped Pupil Lyot Coronagraph for China's Large Segmented Telescope

Kaining Yang, He Sun, Bin B. Ren, Fabo Feng, Yiyun Wu, Jinxin Liu, Linbo Cao, Ruobing Dong et al.

China's next-generation large telescopes, such as the Expandable Aperture Segmented Telescope (EAST) and the Large Optical/Infrared Telescope (LOT), are being planned as flagship facilities for high-angular-resolution astronomy, including the direct imaging and characterization of exoplanetary systems (e.g., exoplanets, circumstellar disks). However, their segmented, centrally obscured apertures present significant challenges for coronagraph design: diffraction from segmented gaps and spiders se…

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astro-ph.GA

Simulations of Dust Content and Attenuation in $z=5-15$ Galaxies

Dhruv T. Zimmerman, Jed McKinney, Desika Narayanan, Caitlin M. Casey, John Chisholm, Alex M. Garcia, Michelle C. Jecmen, Jessica Kelley-Derzon et al.

Correctly modeling the dust attenuation law in galaxies is essential to properly inferring their growth and physical properties. With the rapid discovery of $z>6$ galaxies by JWST and lack of constraints on the properties of dust at these redshifts, we must turn to theoretical models to predict the properties of dust at these redshifts. In this paper, we develop a theoretical foundation for the nature of high-redshift attenuation laws. We analyze $107$ cosmological zoom-in simulations of galaxie…

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astro-ph.EP

Emission spectroscopy of KELT-2A b with Gemini-North/IGRINS-2: hints of a stellar C/O ratio and sub-stellar metallicity

Yuya Hayashi, Stevanus K. Nugroho, Shota Notsu, Changeat Quentin, Peter C. B. Smith, Krishna Kanumalla, Michael R. Line, Jorge A. Sanchez et al.

We present the results of high-resolution emission spectroscopy of the hot Jupiter KELT-2A~b using IGRINS-2 on the Gemini-North telescope, covering the $H$- and $K$-bands at a spectral resolution of $R \sim 45{,}000$. Observations were carried out over five nights, covering both pre- and post-eclipse orbital phases. Stellar and telluric contaminations are removed via singular value decomposition. We detect $\rm H_2O$ at a signal-to-noise ratio of {6.57}, confirming the previous result at a highe…

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astro-ph.SRphysics.plasm-phphysics.space-ph

Magnetic Reconnection Governs the Entire Lifecycle of Solar Eruptive Magnetic Flux Rope

Xinkai Bian, Chaowei Jiang, Qingjun Liu, Xueshang Feng, Pingbing Zuo, Yi Wang

While magnetic flux ropes (MFRs) are widely accepted to exist prior to many solar eruptions, the physical mechanism responsible for triggering and subsequently driving their eruptions remains debated. Classical models commonly attribute eruption onset to ideal magnetohydrodynamic instabilities, particularly the torus instability, while magnetic reconnection is often regarded as a secondary process. Using high-resolution three-dimensional MHD simulations, we investigate the eruption of an MFR tha…

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astro-ph.HEgr-qc

Search for Sub-Solar Mass Binaries in the First and Second Part of LIGO's Fourth Observing Run O4a-O4b

Keisi Kacanja, Kanchan Soni, Alexander H. Nitz

The observation of sub-solar mass neutron stars and black holes would signify a new class of astrophysical objects since these systems are not expected to form via standard stellar evolution. We present the first sub-solar mass search for binaries consisting of neutron star or black holes that uses the data from both the second part (O4b) and first part (O4a) of the fourth observing run of the Advanced LIGO detectors. The search covers primary masses 0.1 to 2 $M_\odot$ and secondary masses 0.1 t…

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astro-ph.EP

ExoEcho: Exoplanet Ephemerides Change Observations. III. A JWST Survey for Transit Timing Variations of 37 Exoplanets

Yunke Wu, Zixin Zhang, Xinyue Ma, Wenqin Wang, Siqi Guo, Cong Yu, Shang-Fei Liu, DiChang Chen et al.

Transit timing variations (TTVs) provide a powerful probe of planetary dynamics and orbital evolution. We extend the ExoEcho project by incorporating James Webb Space Telescope (JWST) transit observations and analyze 84 light curves of 37 exoplanets, including 20 hot Jupiters, 11 Neptune-like planets, and 6 super-Earths. We derive updated transit ephemerides and conduct a systematic search for long-term and periodic TTV signals. We identify two strong TTV candidates, including HATS-6~b and HAT-P…

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astro-ph.GA

Large-scale Environmental Dependence of AGN Activity Revealed by JWST Pa$α$ Emitters

Danyang Jiang, Linhua Jiang, Shuqi Fu, Zijian Zhang, Jie Chen, Chenxi Bao, Yihe Wang, Junya Arita et al.

The role of the large-scale environment in regulating AGN activity remains an open question. We investigate the Mpc-scale environments of 70 AGNs at $z=1.1$-$1.5$ using a highly complete sample of 3,419 Pa$α$ emitters with accurate spectroscopic redshifts from JWST slitless spectroscopic survey. This dataset allows us to robustly trace the environments and quantify the environmental dependence of AGN properties. We measure the eighth-nearest-neighbor surface density of Pa$α$ emitters around each…

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astro-ph.GA

Hot Molecular Hydrogen in Galaxies at Redshift ~ 0.2-1.5 Revealed by JWST

Jie Chen, Linhua Jiang, Shuqi Fu, Zijian Zhang, Danyang Jiang, Jing Wang, Ran Wang, Darshan Kakkad et al.

Molecular hydrogen (H$_2$) is the fundamental component of the molecular gas reservoir that fuels star formation and black hole growth. While prominent hot H$_2$ emission ($\gtrsim 1000$ K) has been explored in nearby galaxies, its excitation mechanisms at higher redshifts remain poorly constrained. We present a systematic study of hot molecular gas traced via ro-vibrational H$_2$ emitters at z~0.2-1.5 using JWST slitless spectroscopy. Exploiting JWST's great sensitivity to near-infrared H$_2$ r…

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astro-ph.GA

A JWST View of Cosmic Star Formation from $z\sim0$ to 9 with Hydrogen Recombination Lines in the COSMOS and GOODS-N fields

Shuqi Fu, Linhua Jiang, Christopher J. Conselice, Zijian Zhang, Danyang Jiang, Jie Chen, Louis Quilley, Fengwu Sun et al.

We combine wide-area COSMOS-3D observations with deeper GOODS-N data from JWST/NIRCam F444W wide-field slitless spectroscopy to trace cosmic star formation over $z\sim0$--9. The observations cover approximately $0.33~\mathrm{deg}^2$ in COSMOS and $60.9~\mathrm{arcmin}^2$ in GOODS-N, with typical $3σ$ integrated line-flux limits of $3.2\times10^{-18}$ and $1.04\times10^{-18}~\mathrm{erg\,s^{-1}\,cm^{-2}}$, respectively. The common $3.9$--$5.0\,μ$m wavelength window probes Br$α$, Br$β$, Pa$α$, Pa$…

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astro-ph.GAastro-ph.HE

Deep X-ray View of a Distant Protocluster Anchored by a Quasar at $z=6.63$: No Evidence for Enhanced X-ray AGN Activity

Shouyi Wang, Feige Wang, Jinyi Yang, Bin Luo, Xiangyu Jin, Fan Zou, Jaclyn B. Champagne, Xiaohui Fan et al.

Whether dense environments accelerate SMBH growth during cosmic reionization remains uncertain because X-ray constraints on $z>6$ protoclusters are rare. We analyze $\sim865$ ks of Chandra observations of J0910-0414 quasar field, a massive protocluster at $z=6.63$. We construct a catalog of 251 X-ray sources and search for AGN among 21 spectroscopically confirmed members, excluding the central quasar. This is the first systematic X-ray AGN census in a $z>6$ protocluster; none of the members is i…

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astro-ph.SRastro-ph.GA

Transients and Stellar Activity as Revealed by Ultraviolet Diagnostic Tracers

Richard de Grijs, Martin A. Barstow, Deepak Chahal, Fabio Favata, Xiaoting Fu, Ana I. Gómez de Castro, Sipra Hota, Firoza Sutaria et al.

Ultraviolet (UV) observations offer unique insights into transient and variable astrophysical phenomena, from the Sun and nearby stars to supernovae and star-forming galaxies. Here, we summarise and review the diagnostic power of the UV spectrum for probing the physical conditions, dynamics and energetics of these events. We trace the historical development of UV astronomy from early satellite missions to the current landscape shaped by the Hubble Space Telescope, the GALaxy Evolution eXplorer,…

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astro-ph.GAastro-ph.CO

The Contribution of Mergers and Accretion to Dark Matter Halo Assembly: An Excursion Set Theory Approach

Hamed Kameli

We study the relative contributions of mergers and accretion to the assembly of dark matter haloes within the framework of Excursion Set Theory (EST). We extend a variance-discretized merger-tree algorithm, which recursively reconstructs all branches of a complete merger tree and introduces a merger-ratio criterion for distinguishing mergers from accretion. The method is validated by comparing the resulting progenitor distributions with the analytical conditional first up-crossing distribution,…

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astro-ph.SRastro-ph.GA

Twisted Pseudodisk and Asymmetric Mass Accretion on the Circumstellar Disk II: Parameter Survey

Masahiro N. Machida, Shingo Hirano, Shantanu Basu

Using three-dimensional magnetohydrodynamic simulations accounting for ohmic dissipation, we investigate the long-term evolution of the infalling envelope for $\sim 100,000$\,yr after protostar formation. The primary control parameter is the initial misalignment angle $θ_0$ between the rotation axis and the magnetic field, varied from $0^\circ$ to $90^\circ$. In all misaligned models ($θ_0 \ne 0^\circ$), the pseudodisk (or infalling envelope) surrounding the circumstellar disk develops a highly…

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astro-ph.EP

The Limits of Tidal Circularization and Atmospheric Escape for Mini-Neptunes and Super-Earths: The Case of TOI-2257 b

M. K. A. Olohoy, Y. A. D. Gelani, R. Barnes

With a 35-day orbital period and $\sim$0.5 eccentricity, TOI-2257 b occupies a sparsely populated corner of transiting mini-Neptune parameter space and may lie near the orbital distance at which tidal and atmospheric escape process become negligible. To test this hypothesis, we performed simulations of the combined stellar, tidal, and atmospheric evolution and confirmed that TOI-2257 b does lie near this boundary, regardless of whether it formed with or without a primordial hydrogen envelope. In…

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astro-ph.SRastro-ph.GA

Tracing Accretion and Inner-Disk Gas Evolution in the Orion Nebula via Br-alpha and CO

Konstantin V. Getman, Maria Claudia Ramirez-Tannus, Jenny Frediani, Kevin L. Luhman, Eric D. Feigelson, Bayron Portilla-Revelo, Christian Rab, Valentin Brunn et al.

We present a systematic spectroscopic study of hydrogen Brackett-alpha (Br-alpha) and carbon monoxide (CO) fundamental-band (4.3-5.2 micron) emission from a homogeneous sample of 0.2-1.5 Msun pre-main-sequence (PMS) stars in the Orion Nebula observed with JWST/NIRSpec-MOS as part of our Chandra-JWST project. Using 73 Br-alpha and 46 CO spectra, we investigate correlations between warm-gas emission, stellar properties, accretion, and environment with censored correlation and regression analyses a…

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astro-ph.EP

Paleo-heat flux estimates across Enceladus derived from flexural response of the ice shell

Chelsea Eakins, Francis Nimmo, Paul Schenk

Saturn's moon Enceladus has active plumes suggestive of locally high heat fluxes at present, and the present-day heating is reasonably well characterized. However, the moon's thermal history is not well understood. In this study, we model flexural deformation of chasmata and dorsae in various regions of Enceladus to find the effective elastic thickness of the ice shell and constrain temporal and spatial variations in heat flux. We find paleo-heat fluxes of 60-$\geq$350 mWm$^{-2}$, with most clus…

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astro-ph.SRastro-ph.EPhep-ph

Chandra-JWST Probing the Effects of Moderate X-Ray Superflares on Protoplanetary Disks

Konstantin V. Getman, Kevin L. Luhman, Bayron Portilla-Revelo, Christian Rab, Valentin Brunn, Eric D. Feigelson, Arjan Bik, Jan Forbrich et al.

Powerful X-ray flares from young stars may rapidly alter the physical and chemical conditions of their planet-forming disks, but direct observational tests remain scarce. We present a Chandra-JWST/NIRSpec study of infrared spectral variability associated with pre-main-sequence (PMS) X-ray flares in the Orion Nebula. Combining six Chandra/ACIS-I observations with three NIRSpec-MOS visits, we analyze two-epoch spectra of 10 X-ray Flare stars and 12 matched non-flaring Controls among 84 observed di…

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astro-ph.IM

Studying the Near-horizon Jet of M87 using Millimeter Balloon-borne VLBI stations

Felix M. Thiel, Dominic W. Pesce, Mayukh Bagchi, Laura M. Fissel, Lindy Blackburn

In this paper we present synthetic Very Long Baseline Interferometry (VLBI) observations of M87 between a near-future configuration of the Event Horizon Telescope (EHT) and one or multiple 2.5 m-class balloon-borne VLBI stations on a northern transatlantic flight trajectory launching from Kiruna, Sweden. These balloon-borne VLBI stations have the advantage of operating above 99.5% of the atmosphere and their motion allows for efficient sampling of the uv-plane. Assuming frequency phase transfer…

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astro-ph.GA

Galactic Outflows and Star-Formation Quenching: A JWST Perspective

Rebecca L. Davies, Sirio Belli

Outflows driven by active galactic nuclei (AGN) are widely considered a key mechanism for regulating and quenching star formation in massive galaxies. However, direct observational evidence linking outflows to quenching has remained elusive for decades. This article reviews recent findings for massive galaxies at cosmic noon ($z\sim 2$), based on sensitive James Webb Space Telescope (JWST) observations tracing both star formation histories (through Balmer absorption lines) and neutral outflows (…

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astro-ph.GAastro-ph.IM

Emergence of high-mass stars in complex fiber networks (EMERGE) VII. Multi-Tracer Column Density Synthesis

Alvaro Hacar, Andrea Socci, Mario Tafalla, Francesca Bonanomi

Obtaining accurate estimates of the gas column density $\mathrm{N(H_2)}$ is crucial to determine the physical conditions of the molecular gas in the Interstellar Medium. This paper introduces the "Multi-Tracer Column Density Synthesis" (MT-CDS) technique, a new empirical approach to derive high dynamic-range column density maps with interferometers such as ALMA. We have compared the integrated intensity maps of two density selective tracers, namely HNC (1-0) and $\mathrm{N_2H^+}$ (1-0), obtained…

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astro-ph.GA

SQuIGGLE: Radio AGN Found Predominantly in Young, Gas-rich Post-starburst Galaxies at z ~ 0.7

Vincenzo R. D'Onofrio, Justin S. Spilker, Krista L. Smith, Rachel Bezanson, Robert Feldmann, Alex J. Geiger, Andy D. Goulding, Jenny E. Greene et al.

The processes that rapidly quench massive galaxies and maintain their quiescence remain poorly understood. Substantial molecular gas reservoirs can survive this shutdown in post-starburst galaxies, raising the question of what prevents the remaining gas from efficiently forming stars. We present deep, subarcsecond VLA 6 GHz observations of 52 massive SQuIGGLE post-starburst galaxies at $z\sim0.7$ to test the prevalence and mechanical impact of radio activity during the gas-rich post-burst phase.…

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astro-ph.GA

Are Broad Mg II Galaxies Fading AGN?

Stephanie M. LaMassa, Michael Eracleous, Jessie Runnoe, Benny Trakhtenbrot, Gisella de Rosa

We analyzed a sample of 494 galaxies from the Sloan Digital Sky Survey (SDSS) I-IV that have unusual properties. They display broadened Mg II $λ$2798 line emission, as would be expected of Type 1 active galactic nuclei (AGN). However, they have weak or absent broad Balmer lines though broadened Balmer lines often accompany broadened ultraviolet lines in Type 1 AGN spectra. We performed a spectral decomposition of these "broad Mg II galaxies'' to assess whether they can be considered fading AGN.…

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astro-ph.SRastro-ph.HE

A Distinct Type of Standstill in Ultra-Compact White Dwarf Binaries

Jan Kára, Liliana Rivera Sandoval, Iwona Kotko, Jean-Marie Hameury, Luis E. Salazar Manzano, Ryan J. Oelkers

AM CVn stars are ultra-compact, semi-detached binaries consisting of a white dwarf primary and a hydrogen-poor secondary. In this work, we analyse the AM CVn-type systems MGAB-V270, ZTF18aaxuusk and ASASSN-19ct, which have similar properties and show unusual post-superoutburst behaviour. We focus on the occurrence of standstill-like phases. In MGAB-V270, superoutbursts are followed by a series of echo outbursts that evolves into a standstill-like phase before the system returns to quiescence. ZT…

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astro-ph.SR

Understanding the Complex Morphology of a Coronal Mass Ejection. III: How to Create a Severe Geomagnetic Storm

Cecilia Mac Cormack, Abril Sahade, Erika Palmerio, Evangelia Samara, Phillip Hess, Robin C. Colaninno, Teresa Nieves-Chinchilla

On April 21, 2023, a complex filament eruption produced an Earth-directed coronal mass ejection (CME) that triggered the first severe geomagnetic storm of solar cycle 25. The primary objective of this work is to understand the physical origin of the severe impact of this CME on Earth. We explore the CME's complex morphology by simulating the eruption using the thermodynamic magnetohydrodynamic (MHD) model CORHEL-CME. We model the pre-eruptive structure as two intertwined magnetic flux ropes and…

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astro-ph.EPastro-ph.IM

Science-Driven Performance Requirements for UV Coronagraph Design: Implications for O$_3$ Detection in Earth-like Atmospheres

Amber V. Young, Giada Arney, Shawn Domagal-Goldman, Tyler D. Robinson, Roser Juanola-Parramon, Christopher Stark, Renyu Hu, Armen Tokadjian et al.

Detecting biosignatures on Earth-like exoplanets from the Proterozoic era requires instrumentation capable of probing near-ultraviolet (NUV) spectral features, particularly ozone (\ce{O3}), which serves as an indirect proxy for molecular oxygen (\ce{O2}) when direct detection is challenging. Using a combination of photochemical-climate modeling and atmospheric retrieval simulations, we quantify fiducial instrument performance requirements for robust \ce{O3} detection and assess the risk of spect…

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astro-ph.GA

MOSS III: MeerKATs view on the galaxy populations in two massive galaxy clusters

Robert Kincaid, Mark Sargent, Pascale Jablonka, Bruno Slaus, Viral Parekh, Shishir Sankhayan, Sameer Salunke, Jean-Paul Kneib et al.

The MeerKAT Observations of the Saraswati Supercluster (MOSS) is an ongoing project attempting to study the radio and optical properties of the core region of the Saraswati supercluster (z = 0.28) and will eventually entail a full survey of the entire supercluster region. Here we use radio catalogs from previous deep pilot MeerKAT L-band (1.28 GHz) observations (angular resolution of 8 arcsec) of the core region of the Saraswati supercluster. The region hosts two galaxy clusters representing dis…

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hep-thastro-ph.HEhep-ph

Coherent states of neutrinos in rotating matter

Alexander Breev, Maxim Dvornikov

We study coherent states of neutrinos electroweakly interacting with rotating matter. We start with the Dirac equation for a massive neutrino propagating in background matter with a coordinate dependent effective potential. Then, we consider the limit of massless particles and the specific matter velocity profile. It allows us to reduce the neutrino Hamiltonian to the harmonic oscillator form. We find the exact solutions of the Dirac equation and construct the creation and annihilation operators…

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astro-ph.IM

Neural networks applied to forecasting the astroclimatic and meteorological parameters in an operational context

C. Weinberger, E. Masciadri, M. De Sepibus, A. Otarola, S. Miesske, C. Veillet, S. Ragland

Forecasting optical turbulence and atmospheric parameters is crucial for science operations of present and new generation ground-based telescopes (ELT) as well as for free-space optical communication (FSOC). These forecasts are also useful to optimize the AO use, particularly in the ELT framework too. Recent research has demonstrated that the AR technique currently provides the best performances in predicting atmospheric and astroclimatic parameters on a time scale of 1 hour (e.g., RMSE 0.1" for…

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