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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.COastro-ph.GA

Morphological Bias: How Ellipticals and Spirals Trace the Cosmic Web Differently

Paula S. Ferreira, Carlos A. P. Bengaly, Renyue Cen

We present a data-driven measurement of galaxy bias and scale-dependent relative bias for elliptical and spiral galaxies using angular auto- and cross-power spectra from DES and DESI Legacy Imaging Surveys DR8. We introduce the cross-tracer clustering ratio (CTCR), which uses the ratio of auto- to cross-power spectra to isolate the relative clustering of morphological tracers as a function of angular multipole $\ell$. Across both surveys, ellipticals are more strongly clustered than spirals; the…

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astro-ph.GAastro-ph.HE

22 Newly Identified Repeating Changing-look AGNs and Evidence for Extreme Broad-line Region Breathing

Litao Zhu, Zhongxiang Wang, Alok C. Gupta, Yiyang Zeng, P. U. Devanand, Karan Dogra, Riya Bhowmick, Ju-Jia Zhang et al.

Changing-look active galactic nuclei (CL AGNs) show the appearance or disappearance of broad emission lines on timescales of years. Among them, the repeating CL (RCL) AGNs may provide a clear clue for our understanding of the CL transitions because the same nucleus crosses some physical boundaries more than once. We search for RCL AGNs in known CL-AGN samples using long-term multi-band light curves, and selected 34 candidates for spectroscopic follow-up. We confirm 25 RCL AGNs, including 22 newl…

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astro-ph.SR

Investigation of projected rotational velocities of Be-type stars in LAMOST DR7

Zhicun Liu, Jiao Li, Jiaming Liu, Xiao-Long Wang, Guozhen Hu, Wenyuan Cui

Stellar rotation plays a key role in the transfer of angular momentum, and a large sample of Be-type stars with reliable projected rotational velocities is crucial for understanding their formation and evolution. In this work, we derive the projected rotational velocities ($v$\,sin\,$i$) of 479 Be-type stars using the Fourier transform method, based on their LAMOST Medium-resolution Survey (MRS) spectra. Our results suggest that the Fourier transform method can provide reliable $v$\,sin\,$i$ val…

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astro-ph.SRastro-ph.EP

Silicate Clouds, SiO, and Molecular Trends across the L-T Sequence: A JWST/MIRI LRS Spectral Library of Brown Dwarfs

Sam Barber, Stanimir Metchev, Genaro Suárez, Samantha Lambier, Paulo A. Miles-Páez, Étienne Artigau, Beth Biller, Adam J. Burgasser et al.

We present the results of a survey program with JWST's MIRI LRS that obtained 5$-$14 $μ$m R~100 spectra of twenty-three L0$-$T6 dwarfs. This spectral type range spans the formation, growth, and sedimentation of silicate condensate clouds, as well as the appearance of methane and ammonia in the atmospheres of brown dwarfs. The initial onset of silicate absorption at spectral type L0 as well as the evolution of this feature with spectral type are both examined in unprecedented detail. We detect 7.…

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astro-ph.GA

Gas-Phase Metallicity and Nitrogen Abundances in Low-Mass Galaxies Down to $M_\star\simeq10^{5.7}\,M_\odot$ at $z\simeq4.5$--$10.1$ from JWST Lensing Cluster Surveys

Hiroya Umeda, Masami Ouchi, Kimihiko Nakajima, Kuria Watanabe, Yuichi Harikane, Yuki Isobe, Moka Nishigaki, Ono Yoshiaki et al.

We analyze 405 deep JWST/NIRSpec spectra of star-forming galaxies at $z=4.5$--$10.1$ from DREAMS and other lensing-cluster surveys to study chemical enrichment in intrinsically faint, low-mass galaxies. The sample covers $M_{\rm UV}\simeq-12$ to $-22$ and reaches $M_\star\simeq10^{5.7}\,M_\odot$, with 50\% of the sources at $M_{\rm UV}>-17.5$ magnified by $μ>3$. From individual spectra and mass-binned stacks, we derive the gas-phase metallicity together with nitrogen and carbon abundances using…

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hep-phastro-ph.COastro-ph.HE

PBH formation and Gravitational Waves as Multi-messenger Signals of First-order Phase Transitions

Bhaskar Dutta, Cash Hauptmann, Peisi Huang, Adrian Thompson

The collapse of false-vacuum domains during first-order phase transitions in the early Universe may lead to primordial black hole (PBH) formation whose signatures form a multimessenger complement to gravitational wave (GW) production. We focus on PBH formation through the gravitational collapse of false-vacuum domains, described using a junction condition formalism. This formalism develops the Schwarzschild collapse criterion dynamically, avoiding the usage of critical overdensity thresholds in…

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astro-ph.IMastro-ph.GA

Star formation, stellar evolution, and planets in high-resolution X-ray imaging

Hans Moritz Günther, Scott J. Wolk, Sean J. Gunderson, Ruchi Pandey, Keivan G. Stassun, Lynne Valencic

Stars set the conditions for planet formation, planet evolution, and habitability -- all major topics in astronomy today. Stars are also important in their own right as the most visible component of galaxies. In cool stars, X-ray emission is powered by magnetic fields, and so far our Sun is the only system in which those fields are spatially resolved. High-resolution X-ray (HiReX) imaging can track the origin and evolution of those fields, see how they connect young stars to their disks and outf…

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astro-ph.GAastro-ph.SR

A JWST, ALMA and VLA survey of the Ophiuchus-A star-forming region: Unveiling hidden dust mass and connecting infrared outflows to their radio origins

Isaac C. Radley, John D. Ilee, Gemma Busquet, Hauyu Baobab Liu, Klaus M. Pontoppidan, Alvaro Ribas, Marc Audard, Eleonora Bianchi et al.

We present an infrared, millimetre, and radio survey of 20 Class 0-III young stellar objects in the Ophiuchus A L1688 star-forming cluster, combining high-resolution (7-25 au) VLA and JWST observations with archival ALMA data. We implement physically motivated models to derive dust and ionised gas properties, spectral behaviour and their relative contributions through the millimetre-centimetre radio spectral energy distribution. Our models reveal circumstellar dust disks that are, on average, te…

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astro-ph.HEastro-ph.SR

Implications of the UV/optical Plateau of AT2018cow

Wenbin Lu, Anthony L. Piro

AT2018cow, the prototypical luminous fast blue optical transient (LFBOT), shows a slowly fading plateau in the UV/optical light lasting at least 5 years after the explosion. The plateau SED is blackbody-like with temperature $\gtrsim$ 2e4 K and an emission radius ~40 Rsun, which has been attributed to a geometrically thin accretion disk around a compact object. Viscously powered disk models, however, require an unusually massive black hole $\gtrsim$ 200 Msun (for viscosity parameter $α$ > 0.01).…

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astro-ph.HE

Assessing the waveform systematics from parameter estimation to population inference with eccentricity

Muhammad Zeeshan, Richard O'Shaughnessy, Natalie Malagon, Katelyn J. Wagner

While masses and spins are routinely used to constrain compact binary formation channels, eccentricity provides an additional and potentially powerful diagnostic of binary origin, particularly for dynamically assembled systems. Recent advances in eccentric waveform modeling now make it possible to search for eccentric signatures in gravitational wave data; however, differences between waveform models can introduce systematic effects that may propagate into astrophysical population inference. In…

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astro-ph.HE

Triple radio flares from tidal disruption events: jet-wind collisions and the discovery of a third radio flare from AT2020vwl

Andrew Mummery, Adelle Goodwin, Colin Christy, Kate Alexander, Noah Franz

Radio flares from tidal disruption events (TDEs) are observed on two distinct timescales: prompt (around the time of optical peak) and delayed (hundreds to thousands of days after optical peak). A recent framework put forward to explain this diversity suggests that super-Eddington winds produce prompt flares while jets launched during a disk state transition at low accretion rates produce delayed flares. A unique observational prediction of this framework is that individual sources showing both…

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astro-ph.HE

A Multiwavelength Study of a Long-Duration VHE Flare from BL Lacertae with VERITAS

Atreya Acharyya, Avery Archer, Priyadarshini Bangale, Joshua Bartkoske, Wystan Benbow, James Buckley, Yu Chen, Jodi Christiansen et al.

We report the first observations of a long-duration very-high-energy (VHE; $E > 100$ GeV) flare from BL Lacertae (VER J2202+422), taken with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). On October 15, 2022, the Fermi-Large Area Telescope (LAT) detected elevated GeV activity originating from this blazar. This triggered a multiwavelength campaign, which includes observations from VERITAS, Swift, NuSTAR, and select optical and radio observatories. VERITAS observed the sour…

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astro-ph.HE

Uncovering Hierarchical Sub-Population of Binary Black Holes

Muhammad Zeeshan, Richard O'Shaughnessy

Enabled by improved instruments with increasing sensitivity, the ongoing gravitational wave census now contains 259 binary black holes, numerous enough to unveil trends, substructure, and subpopulations which may provide key clues to their underlying formation mechanisms. In this work, motivated by evidence for multiple formation channels including hierarchical formation, we build a natively multi component mixture model for the binary black hole population, in which each component has an indepe…

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astro-ph.SR

Pre-main Sequence B Stars Surrounding the Orion Nebula

P. H. F. B. Braz, A. Roman-Lopes, W. J. B. Corradi, E. B. Amôres, M. S. Angelo, F. S. S. Maia, J. F. C. Santos, A. E. Piatti et al.

Pre-main sequence (PMS) early-type stars are rare due to their rapid evolution. Confirming PMS B stars is accordingly valuable for constraining higher mass star formation scenarios. Although the Orion Nebula (ON) region offers an ideal laboratory for such studies, its population of B stars remains poorly characterized. We aim to determine spectral types, masses, and ages of B and early A stars surrounding the ON, to identify robust PMS candidates. We combine optical and near-infrared spectroscop…

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astro-ph.HE

Large-scale emission from gamma-ray binaries: the case of LS 5039

J. R. Martinez, V. Bosch-Ramon

Abridged abstract: Context: Gamma-ray binaries hosting a non-accreting neutron star and a massive star exhibit multi-wavelength emission on different spatial scales. The interaction between their winds produces an outflow that can inflate a bubble or form a bow shock as it interacts with the surrounding medium. LS 5039 shows extended (1 pc-scale) X-ray emission that may arise from one of these large-scale structures. Aims: We explain and predict the large-scale emission from LS 5039. Methods: We…

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hep-phastro-ph.HEastro-ph.SRnucl-th

Solar-System Abundances of $p$-Nuclides Probe Collective Neutrino Oscillations in Supernovae

Alexander Friedland, Derek J. Li, Giuseppe Lucente, Payel Mukhopadhyay, Ian Padilla-Gay, Amol V. Patwardhan

Direct evidence for collective neutrino oscillations in core-collapse supernovae remains elusive. We show that this quantum phenomenon leaves a footprint on the abundance pattern of proton-rich nuclides in the solar system. Modeling the $νp$-process using a $20\,M_\odot$ progenitor, we map out the dependence of the total yields on the starting radius of the oscillations, self-consistently coupling hydrodynamics and nucleosynthesis. The oscillations boost key $p$-nuclides ($^{92,94}\text{Mo}$, $^…

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astro-ph.EP

Ephemeris Refinement for Qatar-4 b, HAT-P-18 b, and CoRoT-1 b with Small Telescope and TESS Observations

Heather B. Hewitt, Mikaela Chamlee, Trinity Hockman, Annalise Igyarto, Dan van der Burg, Federico R. Noguer, Ira Bell, Jeremie Abides et al.

We present updated transit timing measurements for three hot Jupiters (Qatar-4 b, HAT-P-18 b, and CoRoT-1 b) by leveraging data collected from the MicroObservatory Telescope Network, a network of small, robotic ground-based telescopes, and the NASA Transiting Exoplanet Survey Satellite (TESS). By combining these data with archival published results, we present the most precise orbital solutions to date for all three systems, allowing for precise transit time predictions for future missions. We r…

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astro-ph.SRastro-ph.HE

Luminous Red Novae as shock-powered transients I: Electron-scattering wings and deviations from Case B

Albert Sneppen, Kenta Hotokezaka, Christopher M. Irwin

Luminous red novae (LRNe) are a class of optical transients resulting from the mergers of binary stars or common envelope events. The population displays heterogeneous light curves with extended luminosity plateaus and/or secondary peaks, suggested to be powered by hydrogen recombination or shocks between pre- and post-merger ejecta. However, much of their spectroscopic behaviour remains unexplained. Using a sample of six LRNe, we identify telltale spectral evidence for shock processes across th…

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astro-ph.IM

Assembly, integration, and verification of MITESI: an optical testbed for simulating the ELT in the laboratory

Daniel J Ahrer, M. Concepción Cárdenas Vázquez, Thomas Bertram, Peter Bizenberger, Armin Huber, Raphaël Pourcelot, Silvia Scheithauer, Horst Steuer et al.

MITESI is an optical testbed which simulates key characteristics of the ELT, ultimately producing an artificial natural guide star. It was designed primarily to enable testing of the METIS instrument's SCAO system in closed loop. In this contribution, we discuss the assembly, integration and verification process of the testbed, taking the project from design to assembled hardware.

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astro-ph.SR

Stellar heavy-element slope index

Gerd Roepke, Friedrich K. Roepke, David Blaschke

The distribution of heavy elements in stars is described using a phenomenological approach, in which Lagrange parameters related to temperature and the chemical potentials of protons and neutrons are introduced within a freeze-out concept. Slope parameters are considered which describe the gross behavior of the distribution of the heavy elements. Universality and deviations from universality are discussed, and various examples are provided. These slope parameters may be of interest for character…

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astro-ph.HEgr-qc

Multimessenger prospects of quasi-periodic eruptions

Vojtěch Witzany, Alessia Franchini, Matteo Bonetti, Luca Broggi

Quasi-Periodic Eruptions (QPEs) are recurring soft X-ray transients that may be generated by inspirals of stellar-mass objects spiraling into supermassive black holes, known as extreme mass ratio inspirals (EMRIs). Independently, EMRIs and the gravitational-wave signals they generate are one of the key targets for the Laser Interferometer Space Antenna (LISA). What is the potential of a coincident detection of EMRIs both as a QPE and by LISA? Electromagnetic counterparts to LISA events would pro…

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astro-ph.HEastro-ph.GA

Observations of X-ray quasi-periodic eruptions

Thomas Wevers, Joheen Chakraborty, Erwan Quintin, Michal Zajaček, Margherita Giustini

Quasi-periodic eruptions (QPEs) are a novel class of repeating nuclear transients, discovered exclusively in the X-ray band to date. Since their initial discovery in 2019, the QPE sample has grown to 13 sources, exhibiting large amplitude, quasi-regular eruptive variability patterns that are distinct from previously known modes of massive black hole variability. In this chapter, we provide a comprehensive overview of their observational characteristics. We review the X-ray spectral and timing pr…

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astro-ph.GAastro-ph.CO

Non-Thermal Physics Drives Compact, Self-Regulated Galaxy Morphologies at Cosmic Dawn

Michelle S. Park, Sergio Martin-Alvarez, Risa H. Wechsler

James Webb Space Telescope (JWST) has discovered unexpectedly bright, rapidly growing galaxies in the early universe, which were not predicted by most previously existing galaxy formation models. Using synthetic JWST observations of the Azahar simulation suite, we show that comprehensive non-thermal physics ("Full-Physics") produces compact, self-regulated galaxies that match observations from $z = 12$ to $z = 3$. This model also produces broad surface brightness distributions, where the bright…

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astro-ph.EPastro-ph.GA

Very Large Telescope observations of interstellar comet 3I/ATLAS III: High-resolution monitoring of CN and forbidden oxygen emission across the perihelion passage with ESPRESSO

Baltasar Luco, Thomas H. Puzia, Rohan Rahatgaonkar, Juan Pablo Carvajal, Prasanta K. Nayak

3I/ATLAS is only the third known interstellar object to traverse the Solar System. We obtained high-resolution ($R\simeq 140000$) spectroscopy of 3I/ATLAS on 23 nights with VLT/ESPRESSO ($r_{h}=1.67-2.45$au). CN production rates were derived by fitting the $B^2Σ^+-X^2Σ^+$ band, using CometSpec, a publicly released Python package for flexible fluorescence modeling. The three forbidden [OI] lines were modeled to derive the green-to-red (G/R) flux ratio and a CO$_2$/H$_2$O proxy. We fit $Q_{CN}=a(r…

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astro-ph.GA

The first three-dimensional map of thermal phases in the local interstellar medium

Jonathan Shelest, Shmuel Bialy, Troy A. Porter, Mark Wolfire, Matan Berko, Margarita Grinberg

The thermal state of interstellar gas controls whether it remains warm and diffuse or cools into dense clouds. Twenty-one centimetre observations have established a statistical picture of neutral-gas phases, but their three-dimensional architecture has not previously been mapped. Here we present $\mathcal{P}_{\rm 3D}$, a three-dimensional reconstruction of thermal phase in the local interstellar medium (ISM), covering a 1 kpc-diameter region centred on the Sun and sampled on a 2 pc Cartesian gri…

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astro-ph.SRphysics.flu-dyn

Polarization geometry of magnetohydrodynamic turbulence

Raphael Skalidis

We introduce a geometric framework that organizes the second-order statistics of the Elasser fields into polarization states on generalized Poincaré spheres. In this representation, energy, cross-helicity, residual energy, and the phase lag between counter-propagating wave packets emerge as complementary polarization parameters. We derive a Bloch-analogue equation governing the evolution of polarization states and show that distinct polarization geometries are associated with different cascade d…

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astro-ph.GAastro-ph.CO

The Azahar Project: Non-Thermal Physics Drives Star Formation Burstiness and the Evolution of the UV Luminosity Density at Cosmic Dawn

Sergio Martin-Alvarez, Risa H. Wechsler, Debora Sijacki

JWST observations, which have pushed the discovery and characterization of galaxies to cosmic dawn, have revealed significant deficiencies in state-of-the-art galaxy formation simulations, motivating the need for novel, physically grounded models. We present the first results from the Azahar suite of ten high-resolution ($\sim$20 pc), large-volume zoom-in cosmological simulations, which follow the formation of thousands of galaxies and progressively incorporate radiative transfer (RT), cosmic ra…

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astro-ph.HE

Ultraviolet to Infrared Spectroscopy of the Type Ibn SN 2023tsz Suggests a Lower-mass Progenitor

Sergiy S. Vasylyev, Griffin Hosseinzadeh, Luc Dessart, Ori Fox, David J. Sand, Alexei V. Filippenko, Qinan Wang, D. Andrew Howell et al.

Type Ibn supernovae are stripped-envelope explosions whose spectra indicate interaction with dense, helium-rich and hydrogen-poor circumstellar material (CSM), making them important probes of late-stage mass loss and progenitor stripping. We present extensive ultraviolet-to-near-infrared spectrophotometry of the Type Ibn SN 2023tsz, including two epochs of HST/STIS ultraviolet (UV) spectroscopy and ground-based optical and near-infrared follow-up observations. The spectra are dominated by interm…

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astro-ph.GA

How large can galaxies be? Ultra-deep imaging of IC 1101, the most extended known galaxy

Carlos Marrero-de la Rosa, Ignacio Trujillo, Ignacio Ruiz Cejudo, Mireia Montes, Fernando Buitrago, Giulia Golini, Sergio Guerra Arencibia, Andrés Asensio Ramos et al.

The maximum physical extent that galaxies can reach is poorly understood. In this regard, IC 1101, one of the most extended and massive galaxies known, provides a valuable opportunity to constrain the upper limit of galaxy sizes at the present epoch. Previous deep imaging of the system confirmed its enormous extension, but did not indicate whether it has an edge. We explore this issue using the deepest images ever taken of this galaxy; ultra-deep g- and r- band imaging from the INT/WFC, reaching…

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astro-ph.GAastro-ph.COgr-qc

Tighter Dark Matter Constraints from the Projected Mass Method: A Neural Network Enhanced Method for Galaxy Groups and Clusters

Yinbo Huang, David Benisty

Measuring the total mass of the Milky Way and nearby galaxy groups is difficult because classical dynamical estimators rely on assumptions about satellite orbital geometry that are rarely satisfied in practice, and because only a handful of satellite galaxies are typically available as kinematic tracers. We present a new framework that corrects the well-known Projected Mass Estimator (PME) using a residual neural network trained on thousands of simulated galaxy groups from the IllustrisTNG cosmo…

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