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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GA

C3PO: A Lyα Emitting Galaxy at $z \sim 9$

Weida Hu, Casey Papovich, Taylor A. Hutchison, Rebecca L. Larson, Pablo Arrabal Haro, Steven L. Finkelstein, Nikko J. Cleri, Lu Shen et al.

We present deep, $>10$ hr, JWST NIRSpec G140M and G395M observations of a previously known galaxy C3PO-8447 at $z=8.99781$. Our new NIRSpec data from the Carbon-3 plus Oxygen (C3PO) survey detect Ly$α$ emission with an escape fraction of $1.5\pm0.3\%$ and a velocity offset of $210\pm80$ km s$^{-1}$, making C3PO-8447 the third Ly$α$ emitting galaxy confirmed at $z\gtrsim 9$. The galaxy has a low stellar mass of $2.2\pm0.1\times 10^7\ M_\odot$, a young stellar age of $1.6\pm0.2$ Myr, and a low oxy…

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astro-ph.EPastro-ph.GAastro-ph.SR

Trans-Neptunian Object dynamics even better explained by a stellar flyby after 4.5 Gyr of evolution

Susanne Pfalzner, Frank W. Wagner, Marco Bischoff

The Trans-Neptunian objects (TNOs) formed together with the planets from a flat disc of gas and dust but now orbit the Sun mostly on inclined, eccentric orbits. One explanation for the TNOs' orbits is a close flyby of another star. One with a mass of $M_p =$0.8 Msun at $q_p =$ 110 au and $i_p =$70° fits the observations. However, such close encounters were more frequent when the Sun was young and still part of its birth cluster. Assuming that the flyby happened then, we use numerical $N$-body si…

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astro-ph.EPastro-ph.IM

Effect of stellar spot-only spectral lines in high-resolution transit spectroscopy

W. Dethier, E. Cristo, O. D. S. Demangeon, J. P. Lucero, N. C. Santos, B. Tessore

We investigate how a representative single spectral line present only in a stellar spot can introduce distortions in high-resolution planetary absorption spectra. Specifically, we assess whether such spot-induced features may resemble planetary atmospheric absorption and the observational or stellar conditions under which they become significant. Using the SOAPv4 code, we simulated transit observations of an atmosphere-less planet across a star with a spot containing an additional absorption lin…

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astro-ph.EP

Dynamically favorable hosts for submoons around Jupiter and Saturn

Ryan Dahoumane, Valéry Lainey, Kevin Baillié

The long-term stability of small bodies orbiting natural satellites (submoons) in the Solar System has been previously investigated using an analytical approximation of a three-body problem, focusing mainly on tidal forces and neglecting other perturbations. This approach suggests that submoons around most of the regular satellites in the Solar System could be stable. However, no such object has been detected to date. In this work, we extend these previous results by numerically testing the surv…

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astro-ph.GAastro-ph.CO

Bright star-forming galaxies naturally forming at z>10 in the Shark semi-analytic model

Claudia D. P. Lagos, Angel Chandro-Gomez, Chris Power, Aaron S. G. Robotham

The James Webb Space Telescope (JWST) has unveiled the existence of numerous z>10 bright ultraviolet (UV) galaxies, potentially challenging galaxy formation models in a Lambda Cold Dark Matter (LCDM) universe. Modifications to star formation and stellar feedback models have been suggested to alleviate the tension. However, the fundamental challenge is to design a galaxy formation model that simultaneously reproduces observations from z=0 to those at the highest redshifts. Here, we present predic…

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astro-ph.GA

Magnetic Fields in Massive Star-forming Regions (MagMaR). XII. Radiative Torque Alignment and Disruption in NGC6334I

Vineet Rawat, Thiem Hoang, Patricio Sanhueza, Ian W. Stephens, Manuel Fernández López, Paulo Cortés, Jihye Hwang, Junhao Liu et al.

Intense radiation from high-mass stars is expected to significantly affect dust grain alignment and evolution through RAdiative Torques (RATs). We investigate this effect in a massive star-forming region, NGC6334I, using 1.2 mm dust continuum polarization observations from the Atacama Large Millimeter/submillimeter Array. The polarization fraction spans from $\lesssim1\%$ to $\sim10\%$ and decreases with increasing column density, remaining below $2\%$ in dense cores despite high temperatures ($…

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astro-ph.GA

Magnetic Fields in Massive Star-forming Regions (MagMaR). IX. Radiative Torque Alignment and Disruption in NGC6334I

Vineet Rawat, Thiem Hoang, Patricio Sanhueza, Ian W. Stephens, Manuel Fernández López, Paulo Cortés, Jihye Hwang, Junhao Liu et al.

Intense radiation from high-mass stars is expected to significantly affect dust grain alignment and evolution through RAdiative Torques (RATs). We investigate this effect in a massive star-forming region, NGC6334I, using 1.2 mm dust continuum polarization observations from the Atacama Large Millimeter/submillimeter Array. The polarization fraction spans from $\lesssim1\%$ to $\sim10\%$ and decreases with increasing column density, remaining below $2\%$ in dense cores despite high temperatures ($…

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astro-ph.HEastro-ph.IM

Gamma-Ray Bursts and Optical Brightness: Insights from Swift Satellite

Istvan I. Racz, Yasmin Nehme, Lajos G. Balazs

During the examination of optical properties of gamma-ray bursts (GRBs) measured during the life of the Neil Gehrels Swift Observatory satellite, significant discoveries were made. While the satellite measures gamma, X-ray, and optical data simultaneously, in many cases, only an upper limit is established in the optical domain. Hence, survival analysis, a.k.a. dependability modelling, was necessary, serving as a tool for studying samples where some cases are bound only by the upper limit, as men…

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astro-ph.HE

The Jet Properties and Accretion Regime for the Blazar Sequence

Qingchen Long

The puzzling bimodality displayed by blazars on the broad-band spectral indices ($α_{\rm ro}-α_{\rm ox}$) plane is still an open question. To investigate its physical origin, we compiled a sample comprising 136 flat-spectrum radio quasars (FSRQs), 64 low-synchrotron-peaked BL Lac objects (LBLs), 39 intermediate-synchrotron-peaked BL Lac objects (IBLs), and 105 high-synchrotron-peaked BL Lac objects (HBLs). Our results show that (FSRQs+LBLs)$\rightarrow$IBLs$\rightarrow$HBLs follow a \reflectbox{…

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astro-ph.GAhep-ex

Constraints on mu-variations from the methanol CH3OH thermal lines in the Galaxy at galactocentric distances of 1.5 < D_GC < 13 kpc

A. I. Shtein, J. S. Vorotyntseva, S. A. Levshakov

In this study, constraints are set on hypothetical variations of the fundamental physical constant mu = m_e/m_p - the electron-to-proton mass ratio - based on thermal emission lines of E-methanol (CH3OH) in the 216-220 GHz frequency range. Molecular spectra toward seven massive clouds located across a wide range of galactocentric distances (1.5 = (0.5+/-0.5)*10^(-7) does not indicate statistically significant changes in mu at the 1 sigma confidence level of 5*10^(-8), which is in good agreement…

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astro-ph.IMhep-ex

Reconstruction of Shower-like Events in NEON Using Likelihood and Graph Neural Network Methods

Sujie Lin, Weiqin Huang, Yihan Liu, Chengyu Shao, Lili Yang, Huiming Zhang

The Neutrino Observatory in the Nanhai (NEON) is a proposed deep-sea neutrino telescope deployed in the South China Sea. Accurate reconstruction of shower-like events is crucial for neutrino energy measurements and multi-messenger astronomy, yet it poses significant challenges due to seawater optical attenuation, irregular detector geometry, and substantial $^{40}\mathrm{K}$ ambient background. In this work, we present the first comprehensive reconstruction framework for shower-like events in NE…

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astro-ph.GA

Search for intranight optical variability in a large sample of intermediate-mass black holes

Himanshu Sharma, Gopal-Krishna, Vibhore Negi, Hum Chand, Krishan Chand, Anshul Kumar Sharma

Using the extensive archival database of the Zwicky Transient Facility (ZTF) survey, we have investigated intranight optical variability (INOV) in a large sample of low-mass active galactic nuclei (LMAGN) powered by intermediate-mass black holes (IMBHs). After applying a sequence of well-motivated selection filters, we constructed an unbiased, representative sample of 62 IMBHs for which $r$-band intranight photometric sequences are available in the ZTF database, yielding 167 sessions with a mini…

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astro-ph.IM

Night-sky emission correction techniques for high-resolution spectroscopy: Demonstration with NIRPS

Avidaan Srivastava, François Bouchy, Xavier Dumusque, Étienne Artigau, René Doyon, Neil J. Cook, Danuta Sosnowska, Flavie Bélanger et al.

Ground-based spectrographs operating in the near-infrared (NIR) regime are hampered by various absorption and emission features of Earth's atmosphere. While considerable attention has been paid to mitigating telluric absorption, correcting telluric emission features remains non-trivial and can significantly affect the observation of faint targets. We aim to develop and implement automated algorithms for sky background emission correction in the context of high-resolution spectroscopy. These empi…

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astro-ph.IM

3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper V. Key Scientific Mission: Compact-Object Time-Domain Science

Juhan Kim, Yong-Woo Kang, Sang Hyun Lee, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang et al.

An isolated compact object retains the point-source resolving power of the space-based slitless spectrograph. The baseline wavelength range is 0.2--1.5 $μ$m. The planning baseline uses $R \simeq 1000$ for broad and faint transient spectra and reserves selectable bands at $R \simeq 5000$ for accretion-disk profiles, velocity structure, and precision line ratios. Broad features can be measured after binning the native $R \simeq 5000$ data to lower resolution. Rapid-response spectroscopy follows gr…

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astro-ph.IM

3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper IV. Key Scientific Mission: Solar-System Small Bodies and Planetary Defense

Juhan Kim, Yong-Woo Kang, Sang Hyun Lee, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang et al.

The baseline 0.2--1.5 $μ$m observatory provides rapid-response astrometry, visible and near-infrared taxonomy, rotation and phase curves, recovery, and long-arc orbit improvement for near-Earth objects and other small bodies. The instrument study also evaluates calibrated throughput to 2.70 $μ$m with a 3.0 $μ$m operational band-edge goal. A reduction to 2.5 $μ$m remains the formal engineering off-ramp if thermal, detector, cooling, mass, power, or cost constraints require it. The 3.5-meter Segme…

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astro-ph.GA

Evolution of Virial Clouds - II: From the Formation of First Stars up to their Explosion

Noraiz Tahir, Asghar Qadir, Francesco De Paolis, Noor Fatima

The existence of cold gas and dust clouds close to the cosmic microwave background (CMB) temperature was proposed as a potential repository for a significant fraction of the missing baryons in galactic halos. While the evolution of the virial clouds from the last scattering surface (LSS) ($z=1100$) up to the formation of Population III (Pop III) stars ($z=48$) was studied in [N. Tahir, A. Qadir, M. Sakhi, \& F. De Paolis, The Euro. Phys. Jour. C 81, 827 (2021)] (Paper I), the subsequent evolutio…

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astro-ph.GAstat.ME

A Spatio-Temporal Self-Propagating Log-Gaussian Cox-Hawkes Process for Star Formation Modelling

Qihan Zou

Stochastic self-propagating star formation models describe galactic structure through local triggering and feedback but are commonly formulated using discrete spatial cells and time steps. We extend the spatio-temporal log-Gaussian Cox-Hawkes framework to obtain the Spatio-Temporal Self-Propagating Log-Gaussian Cox-Hawkes Process, a continuous point process model for the locations and times of star-forming events. The model combines spontaneous formation, correlated environmental effects, outwar…

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gr-qcastro-ph.HEastro-ph.IMcs.LGphysics.comp-ph

Introducing SINFONIA: Symplectic, slimplectic and Magnusian (Neural) Flows for Orbital Numerical Integration and Acceleration

Lidia J. Gomes Da Silva

Long-duration gravitational-wave modelling must resolve fast orbital motion together with slow dissipative evolution while preventing small numerical errors from accumulating into secular phase drift. Here we ask whether the finite-time evolution map itself can be learned as an explicit, differentiable, structure-preserving object and then repeatedly composed through a complete inspiral. We construct three neural-flow architectures: a symplectic and slimplectic flow on Galley's doubled phase spa…

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astro-ph.SRastro-ph.GA

NGC 1901: A new benchmark cluster for gyrochronology in the TESS Southern continuous viewing zone

Mara Bernizzoni, Timothy R. Bedding, Prasad Mani, Luke G. Bouma, Courtney L. Crawford, Jason Lee Curtis, Benjamin T. Montet, Samir Nepal et al.

We use Gaia DR3 astrometry and TESS time-series photometry to study NGC 1901, a sparse open cluster in the TESS Southern continuous viewing zone, that has been neglected due to its proximity on the sky to the Large Magellanic Cloud. We refine its membership list and measure rotation periods for 32 high-confidence rotating stars. By applying the gyro-interp empirical model, we calculate a gyrochronal age of 830 $\pm$ 50 Myr. Because NGC 1901 possesses a sub-solar metallicity of [Fe/H]$\approx -0.…

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astro-ph.SRphysics.space-ph

Bifurcations in the Heliosphere: Global-scale Coronal Pseudostreamer Evolution and the Creation of Secondary Heliospheric Current Sheets

Lizet S. Casillas, Benjamin J. Lynch, Victor Réville, Olga A. Panasenco, Marco Velli

The heliospheric current sheet (HCS) is the boundary between open magnetic fields of opposite polarity in the solar wind that connect back to their respective open flux regions in the corona. The HCS is often described as a disc-like sheet warped by the combined effects of the inclination of the magnetic equator on the Sun, solar rotation, and solar wind expansion. The HCS is an extension of the helmet streamer belt-the closed-flux region resulting from the global dipole component of the observe…

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astro-ph.GA

Turbulent gas-rich discs at high redshift: the origin of early massive stellar bars

Joss Bland-Hawthorn, Thor Tepper-Garcia, Chris Hamilton, Johan M. Villa-Alatorre, Oscar Agertz, Takafumi Tsukui, Ken Freeman

Recent observations combining the power of ALMA and JWST have revealed large ($3-7$ kpc), massive ($3-10\times10^{10}\,\mathrm{M}_\odot$) stellar bars at $z=4-5$ when the Universe was only 1.2-1.6 Gyr old. At this early epoch, the host galaxy was baryon-dominated (typically 75\% gas, 25\% stars) within the observed extent of the disc ($8-15$ kpc). Using NEXUS $N$-body/hydrodynamic simulations, we show that such bars can form promptly (400$-$800 Myr), provided the disc mass fraction is high ($f_{…

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astro-ph.HE

Radiative Efficiency Enhancement by Electromagnetic Energy Dissipation in Strongly Magnetized Supercritical Accretion Flows around Kerr Black Holes

Hiroyuki R. Takahashi, Ken Ohsuga, Ryohei Kobayashi, Akihiro Inoue, Yuta Asahina, Akira Nukada, Taisuke Boku

We investigate how black hole spin and the amount of magnetic flux affect electromagnetic energy dissipation and radiation transport in supercritical accretion flows. For this purpose, we perform general relativistic radiation magnetohydrodynamic simulations of MAD and SANE accretion flows with different black hole spins. In the high-spin MAD model, we find that a fraction of the electromagnetic energy extracted by the Blandford--Znajek mechanism is dissipated near the disk surface in the vicini…

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gr-qcastro-ph.HE

Non-extensive entropy signatures in compact star

B. N. Jayawiguna, M. H. Al Ghifari, A. Rohim, A. Sulaksono

The non-extensive entropy models applied to the black-hole horizon are connected to the generalized Einstein--Hilbert action, $f(R)$, via the Wald entropy formalism. We demonstrate that quark star configurations characterized by the MIT bag model under this modified gravity approach conform to the observational lower and upper bounds established for compact objects linked to HESS J1731$-$347 and GW190814. Furthermore, we assess the effective energy conditions and corresponding speed of sound to…

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astro-ph.GA

CLAS+: A large catalog of Changing-Look AGN candidates selected through S-PLUS narrow-band photometry

L. Nakazono, L. L. Oliveira, R. R. Valença, P. Sánchez-Sáez, G. Oliveira-Schwarz, N. M. Cardoso, A. L. O'Mill, S. Panda et al.

Changing-look active galactic nuclei (CLAGN) exhibit rapid spectral transitions on timescales of months to years, challenging standard AGN unification models and providing unique insight into accretion-disk variability and obscuration processes. Despite their scientific importance, systematic searches for CLAGN remain limited by the scarcity of multi-epoch spectroscopy and the difficulty of constructing large samples efficiently. We introduce CLAS+, a catalog constructed by comparing synthetic p…

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astro-ph.GA

Multi-tracer exploration of molecular gas in main sequence galaxies at z~4.5

M. Dessauges-Zavadsky, M. Béthermin, M. Ginolfi, L. Vallini, A. Faisst, M. -Y. Xiao, F. Pozzi, P. Cassata et al.

Molecular gas masses in high-z galaxies are inferred from indirect tracers, whose respective reliability remains poorly constrained. In particular, the bright [CII] 158$μ$m line is now widely used as a molecular gas tracer at z>4, yet direct observational tests against CO remain scarce. We search for CO(4-3), CO(5-4), and [CI](1-0) lines in three of the most [CII]-luminous galaxies at z~4.5 from the ALPINE survey to assess the detectability of these lines in high-z main-sequence (MS) galaxies an…

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astro-ph.IM

The Accretion Explorer Interferometer (AEI) Phase I NASA Innovative Advanced Concepts Final Report

Kimberly A. Weaver, Jenna M. Cann, Kenneth Carpenter, Maurice Leutenegger, Takashi Okajima, Scott Rohrbach, Liz Matson, Craig Stevens et al.

We must create superb X-ray images to understand the detailed physical processes behind some of the most powerful astronomical objects. The need to achieve this capability has been known for decades. But as time proceeds, X-ray astronomy falls further behind other wavebands that are steadily increasing their imaging capacity. Radio astronomy in particular has reached an angular resolution on the order of micro arcseconds via aperture synthesis interferometry, using the interference of electromag…

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astro-ph.HEgr-qc

Observational selection effects on radio pulsars are minimal for masses, but significant for orbits and spins

Lisa V. Drummond, Katerina Chatziioannou, Emmanuel Fonseca

The masses of Galactic pulsars in binaries measured through radio timing point to structure in the mass distribution with implications for dense matter and astrophysical formation processes: a bimodal shape with peaks at ${\sim} 1.3\,M_\odot$ and ${\sim} 1.6\,M_\odot$, with a cutoff above ${\sim}2\,M_\odot$. However, this observed population of radio pulsars is shaped not only by intrinsic pulsar properties, such as birth masses, binary evolutionary pathways and dense-matter constraints, but als…

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astro-ph.EPphysics.ao-ph

Evolutionary pathways toward survival of a thick CO2- or SO2-rich atmosphere on the lava world TOI-561 b

Emma Postolec, Tim Lichtenberg, Johanna K. Teske, Harrison Nicholls, Mara Attia, Anjali Piette, Lisa Dang, Nicole L. Wallack et al.

Rocky planets evolve through the exchange of volatiles between their interiors and atmospheres, an interplay still poorly constrained by observations. Remarkably, highly irradiated ultrashort-period (USP) exoplanets may offer a window into this exchange -- some retain low bulk densities compatible with volatile-rich envelopes surrounding rocky interiors, indicating possible secondary atmospheres. TOI-561 b is a prime example, with a bulk density of $4.3\pm0.4$ g cm$^{-3}$ and recent JWST observa…

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astro-ph.HE

Thermal and non-thermal emission from supermassive black hole circumbinary disks: Disks, Coronae, Streams, and Cavities

Chris Nagele, Julian H. Krolik, Brooks E. Kinch, Jeremy D. Schnittman, Scott Noble

The search for electromagnetic signals from supermassive black hole (SMBH) binary systems is one of the cornerstones of multi-messenger astrophysics, complementing gravitational wave observations of such systems by pulsar timing arrays and LISA. Although extensive simulations have been run to understand the time variability of the bolometric luminosity from accreting binary SMBH systems, comparatively few spectral predictions have been made, and none that go beyond simple emission models. In thi…

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astro-ph.SRastro-ph.EPastro-ph.GA

Infrared-excess sources in VVV: candidate debris discs, SED characterization, and variability analysis

P. Esteves, R. K. Saito, C. Chavero, V. Fermiano, D. Minniti, B. W. Borges, C. Cáceres, Z. Guo et al.

Debris disks around main-sequence stars provide important insights into planetary formation and evolution; however, identifying these systems in the Galactic plane, where high interstellar extinction and source crowding are significant, remains challenging. Deep, wide-area surveys such as the VISTA Variables in the Via Lactea (VVV) ESO Public Survey provide multi-epoch infrared observations, enabling systematic searches in these environments. We present a method to construct a refined sample of…

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