UchUchU

Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.SRastro-ph.GAastro-ph.HE

Ejecta clumps revealed by study of reverse-shocked ejecta through MUSE integral field spectroscopy of SNR 0509-67.5

Priyam Das, Ivo Seitenzahl, J. Martin Laming, Gilles Ferrand, Simon J. Murphy, Ashley Ruiter

We report the discovery of a spatially resolved clumpy ejecta structure in the reverse-shocked ejecta of SNR 0509-67.5, revealed through multiple faint and broad forbidden coronal emission lines in deep MUSE observations. We also identify two new broad coronal emission lines not reported before in this remnant, [Fe xi] 7894 A and [Fe x] 6374.5 A , which extend the set of previously reported [Fe xv] 7059.59 A, [Fe xiv] 5302.86 A , [Fe ix] 8236.55 A , [Ca xv] 5695 A, and [S xii] 7611.0 A. Near-con…

Read →
nucl-thastro-ph.HEastro-ph.IMhep-phnucl-ex

Generative artificial intelligence for reconstructing neutron-star matter

Julia Yu. Panteleeva, Herzallah Alharazin, Evgeny Epelbaum

Neutron-star cores hold the only known matter in the universe that is simultaneously cold and strongly interacting, compressed beyond nuclear density into a state of unknown composition. The equation of state links stellar masses, radii and tidal deformabilities to this regime, but recovering this key quantity from sparse observations is an ill-posed inverse problem. Existing analyses bury a prior in a fixed functional form, unevenly weighting admissible solutions and biasing the result. We reco…

Read →
astro-ph.IM

EON-SII: Design of a transportable picosecond stellar intensity interferometer for compact-star astrophysics

Thomas Schweizer, Josef Eder, Jürgen Besenrieder, Razmik Mirzoyan, Carina Haider, Olaf Reimann, Derek Strom, Roland Walter et al.

Stellar intensity interferometry (SII) measures correlations in photon-arrival fluctuations recorded by telescopes observing bright celestial sources. It can resolve angular scales far smaller than those accessible to a single optical telescope and is largely insensitive to atmospheric turbulence. After the first demonstration of SII on Sirius in 1956, Hanbury Brown and Twiss used the technique to measure the diameters of 32 stars. More recently, VERITAS, MAGIC, H.E.S.S., and CTAO's LST-1 have r…

Read →
astro-ph.SRastro-ph.GAastro-ph.HE

Formation of heavy double neutron stars II: the role of heavy first-born neutron stars and low metallicity

Ashwathi Nair, Simon Stevenson

The high total mass of GW190425 challenges our understanding of double neutron star (DNS) formation, as no such heavy ($\ge 3$\, M$_\odot$) DNS system has been observed in the Milky Way disk. Numerous formation scenarios have been proposed to explain its formation. We test these within a self-consistent binary evolution framework calibrated to the Galactic DNS population. In Paper~I of this series, we studied the evolution of a $1.4$\,M$_\odot$ neutron star (NS) in a binary with a $2.5$--$10$\,M…

Read →
astro-ph.HEhep-phnucl-th

Density-induced dark-baryon conversion in $Δ-$admixed hypernuclear neutron stars

Niyar Prabhat Kalita, Vivek Baruah Thapa, Bhanu Prakash Pant, Anil Kumar, Partha Konar

We investigate density-induced conversion of neutrons into a neutral dark baryon $χ$ in cold, charge-neutral, $β$-equilibrated neutron-star matter containing hyperons and all $Δ(1232)$ quartet. The hadronic sector is modeled within a density-dependent covariant density-functional framework using the DDME2 parametrization. A scalar Higgs portal is included as a possible interaction channel between the visible and dark sectors, although its mean-field contribution is negligible for the couplings a…

Read →
astro-ph.EP

Discovery of an Eccentric Hot Super-Jupiter Leaving the Transiting Geometry of the Early-A-type star TOI-1355

Noriharu Watanabe, Norio Narita, Akihiko Fukui, Bun'ei Sato, Keisuke Isogai, John H. Livingston, Jerome P. de Leon, Daniel Huber et al.

Hot Jupiters orbiting hot stars ($T_\mathrm{eff} > 7000$ K) are suggested to have experienced high-eccentricity migration, often evidenced by the tendency for misaligned orbits, despite their circular orbits. In this paper, we present the discovery of TOI-1355 b: an eccentric ($e\sim0.22$) hot Jupiter with a mass of $m_{\mathrm{p}}\sim5.8M_J$ and a radius of $R_{\mathrm{p}}\sim 1.4R_J$ orbiting an A-type star with a period of about $2.17$ days, identified from the TESS transit survey and subsequ…

Read →
astro-ph.GAastro-ph.SR

Candidates for the most [$O_{III}$] $\lambda5007$-luminous planetary nebula in the Milky Way. I. Integrated light properties of NGC 6572, NGC 6884, and M 1-71

Azlizan A. Soemitro, Martin M. Roth, Jeremy R. Walsh, Ana Monreal-Ibero, Brigitte G. A. Pruijt, Nicholas Chornay

The bright-end cutoff of the planetary nebula luminosity function (PNLF) serves as an extragalactic standard candle. However, the physical properties of planetary nebulae (PNe) at the PNLF cutoff have been studied only in nearby galaxies, where the PNe appear mostly as point sources. Galactic PNLF is further poorly constrained, primarily due to uncertainties in Galactic PN distances. Following a recent Galactic PNLF survey based on Gaia distances, we aim to characterise PN candidates at the Gala…

Read →
astro-ph.GA

Diffuse Dwarf Galaxies in Galaxy Clusters: I. Stellar Populations and Radial Gradients

Arsen Levitskiy, Duncan A. Forbes, Jonah S. Gannon, Yimeng Tang, Anna Ferré-Mateu, Aaron J. Romanowsky, Jean P. Brodie, Warrick J. Couch et al.

We use Keck/KCWI spectroscopy to study one ultra-diffuse galaxy (UDG) and five Nearly-UDGs (NUDGEs) in the Perseus cluster, together with an additional UDG in the Coma cluster. As the first paper in a series, we focus on the global and radial stellar population properties of our sample. We find that these galaxies host intermediate-to old stellar populations, with typical ages of ~7 Gyr, low metallicities ([M/H]$\simeq$ -0.9 dex), and enhanced [Mg/Fe] abundances (~0.3 dex), consistent with previ…

Read →
astro-ph.IMastro-ph.EP

The Roman Coronagraph Community Participation Program: calibration strategy for the Mueller matrix using on-sky sources

Toshiyuki Mizuki, Justin Hom, Bertrand Mennesson, Ramya M. Anche, Maxwell A. Millar-Blanchaer, Vanessa P. Bailey, Koji Kawabata, Mitsuhiko Takeuchi et al.

The Nancy Grace Roman Space Telescope Coronagraph Instrument will provide space-based polarimetric observations of circumstellar disks and exoplanetary systems. Accurate reconstruction of the linear polarization fraction requires calibration of the instrumental Mueller matrix using polarized and weakly polarized standard stars. We constructed a candidate catalog by combining published optical polarimetry with Gaia DR3 astrometry and photometry and selected separate samples for coronagraphic cali…

Read →
astro-ph.IMastro-ph.EP

The Roman Coronagraph Community Participation Program: early calibration plan and pilot observation of a companion

Julien H. Girard, Eric Cady, Neil T. Zimmerman, Clarissa R. Do Ó, Jingwen Zhang, Guillermo Gonzalez, Bijan Nemati, Vanessa P. Bailey et al.

Roman is set to launch in weeks! The Coronagraph Instrument - technology pathfinder for future direct imaging missions - is ready to fly too. According to predictions, laboratory tests and high fidelity simulations, it will open a new contrast regime enabling the imaging of mature, giant planets in visible reflected light. The Community Participation Program is responsible for preparing a comprehensive observing program with associated data processing software and calibrations. We give a brief u…

Read →
physics.plasm-phastro-ph.HEastro-ph.IMastro-ph.SRphysics.space-ph

The FLARE Facility

Hantao Ji, Jongsoo Yoo, Peiyun Shi, Euichan Jung, Kush Maheshwari, Adam Robbins, Sunghyun Son, Adam Stanier et al.

The Facility for Laboratory Reconnection Experiments (FLARE) has been constructed to study magnetic reconnection in multiple X-line regimes relevant to space, astrophysical, and fusion plasmas. Building upon the successful design of the Magnetic Reconnection Experiment (MRX), FLARE features a larger physical volume, stronger magnetic fields, and an independent ohmic heating drive to significantly extend the accessible parameter space, targeting Lundquist numbers up to S ~ 10^5 and normalized sys…

Read →
astro-ph.HE

Sudden emergence of a low-frequency hard X-ray lag in the Seyfert 1 galaxy Mrk 1044

Jia-Lai Kang, Jun-Xian Wang

Hard X-ray lags, where low frequency variations in the hard X-ray band lag behind those in the soft band, have been detected in many active galactic nuclei (AGNs) and are generally attributed to the inward propagation of accretion-flow fluctuations through an extended corona. In a long XMM-Newton observation of the Seyfert 1 galaxy Mrk 1044, we found a remarkable transition in the lag behavior within a single exposure, while the X-ray flux and spectral shape remained largely unchanged. During th…

Read →
astro-ph.GA

The VariableTNG project: how baryonic mechanisms shape galaxy properties

Kexin Liu, Hong Guo, Luis C. Ho, Tao Wang, Yikai Liu, Volker Springel

We use 50 Sobol-sampled VariableTNG simulations, varying eight subgrid parameters at fixed cosmology and initial conditions, to determine which baryonic processes regulate galaxies and black holes at $z=6$ and $z=8$. We compare the simulations with recent high-redshift measurements of the stellar mass function, star-forming main sequence, stellar and gas-phase mass-metallicity relations, stellar mass-size relation, and black-hole host and accretion properties. The simulations reproduce several b…

Read →
astro-ph.IMastro-ph.EP

The Roman Coronagraph Community Participation Program: corgisim - a simulation suite for the Nancy Grace Roman Space Telescope Coronagraph Instrument

Jingwen Zhang, Sophie Noiret, Maxwell A. Millar Blanchaer, Jason Wang, Alexis Lau, Neil Zimmerman, Jessica Gersh-Range, Eric Shen et al.

NASA's Roman Space Telescope will feature a pathfinder Coronagraph Instrument to demonstrate advanced high-contrast imaging from space, paving the way for future missions like the Habitable Worlds Observatory. The Coronagraph Instrument could obtain imaging, polarimetry and spectroscopy of Jupiter analogs in reflected visible light for the first time. We present the development of an open-source simulation package ``corgisim'' as part of the Roman Coronagraph Community Participate Program. Built…

Read →
astro-ph.HEastro-ph.CO

AT 2020afjz (TSS2020a): The First Fast Extragalactic Transient Discovered by TESS

Ryan Ridden-Harper, Hugh Roxburgh, Clarinda Montilla, Lancia Hubley, James Freeburn, Brayden Leicester, Andrew Moore, Zachary G. Lane et al.

We report the discovery of AT 2020afjz (TSS2020a): the first hour-scale extragalactic transient discovered in optical wavelengths whose complete evolution -- from explosion onset to decay -- is temporally resolved, and the first such transient discovered by TESS. AT 2020afjz was identified as a $>10σ$ detection in the pilot HiLaTS program run within the TESSELLATE Sky Survey, which blindly searches for transient phenomena in TESS data with the TESSELLATE pipeline. Through cross-matching with leg…

Read →
astro-ph.HE

Surface gravity wave on a neutron star ocean trapped around a magnetic pole

Shin'ichirou Yoshida

A warm neutron star is expected to have a fluid "ocean" of heavy elements at its outermost part of the outer crust. As is on the terrestrial ocean, the neutron star ocean also has surface gravity waves. Around a magnetic pole of a star, the ocean may have a dip due to the strong magnetic pressure coming into play in the hydrostatic balance of the ocean. The dip enables the surface gravity wave to be trapped around the magnetic pole to form eigenmodes. The frequency of the mode is much lower than…

Read →
astro-ph.EPastro-ph.SR

JWST-MIRI's multi-dimensional view of mass loss in the irradiated disks of NGC 1977

Alice S. Booth, Qijia Zhou, Jinyoung Serena Kim, Karin Öberg, Jenny Calahan, Klaus Pontoppidan, Thomas J. Haworth, Ilaria Pascucci et al.

The evolution of protoplanetary disks, and consequently the outcomes of planet formation, are thought to be significantly altered in regions containing massive stars. Extreme cases in the Orion Nebula Cluster (ONC) demonstrate the impact of external irradiation (FUV$\gtrsim10^{4}$ G$_{0}$) on disk evolution, but intermediate environments remain less observationally constrained. We present JWST/MIRI Medium Resolution Spectroscopy (MRS) observations of seven proplyds in NGC 1977 exposed to an exte…

Read →
astro-ph.EP

Atmospheric Reconnaissance of TRAPPIST-1 f with JWST NIRISS SOSS: No Evidence for the Transit Light Source Effect

Olivia Lim, René Doyon, Ryan J. MacDonald, Étienne Artigau, Michael Radica, Mykhaylo Plotnykov, Alexandrine L'Heureux, Caroline Piaulet-Ghorayeb et al.

In just over three years of operation, JWST has observed all seven planets of the TRAPPIST-1 system. The two innermost planets were found to have little to no atmosphere, barring the presence of high-altitude aerosols. Here we present the first JWST transit spectra of the habitable-zone exoplanet TRAPPIST-1 f, which were obtained with NIRISS SOSS over the course of five transits. At least one stellar flare occurred in each visit, but unlike observations of closer-in TRAPPIST-1 planets, no eviden…

Read →
astro-ph.IM

On-sky demonstration of dual-field interferometry at the CHARA Array

Narsireddy Anugu, John D. Monnier, Douglas R. Gies, Jeremy Jones, Robert Klement, Stefan Kraus, Rainer Köhler, Karolina Kubiak et al.

Dual-field interferometry uses a bright reference star for real-time fringe tracking, allowing a second beam combiner to record long coherent integrations on a fainter off-axis science target. At the Center for High Angular Resolution Astronomy (CHARA) Array, we implement this mode using the six-telescope MIRC-X and MYSTIC beam combiners in the H and K bands, respectively. We first demonstrated this capability in summer 2025 on the hierarchical triple $α$~Piscium. MIRC-X tracked component A in t…

Read →
astro-ph.IM

The Roman Coronagraph Community Participation Program: target database and tools

Dmitry Savransky, Rifah Tasnim, Saanika Choudhary, Hovik Grigoryan, Justin Hom, Bijan Nemati, Neil Zimmerman, Ramya Anche et al.

The Nancy Grace Roman Space Telescope, set to launch in Fall 2026, will carry the Coronagraph Instrument, which will, for the first time, demonstrate high-contrast imaging with active wavefront control in visible wavelengths from space. In preparation for execution of the Coronagraph's commissioning and observing programs, the Roman Coronagraph Community Participation Program (CPP) has developed a target database and associated ecosystem of publicly accessible tools for observation planning and…

Read →
astro-ph.IMastro-ph.EP

The Roman Coronagraph Community Participation Program: Observation planning and data reduction for polarimetric mode

Ramya M Anche, Toshiyuki Mizuki, Justin Hom, Alexis Lau, Saanika Choudhary, Jaren N. Ashcraft, Clarissa Do O, Tsutsumi Nagai et al.

Reflected-light polarimetry of exoplanets constrains and resolves degeneracies in atmospheric properties, while polarized light observations of debris disks enable the characterization of dust-grain properties. The best-effort polarimetric mode of the Roman Coronagraph Instrument will be able to perform multi-wavelength observations of planetary systems using both the Hybrid Lyot Coronagraph (HLC) and the Shaped Pupil Coronagraph (SPC). This paper presents an overview of observation planning, si…

Read →
gr-qcastro-ph.GA

Exact black hole solutions with semi-symmetric vectorial torsion

Lehel Csillag, Tiberiu Harko

Semi-Symmetric metric gravity extends general relativity by introducing a semi-symmetric connection with vectorial torsion. The modified field equations contain extra contributions from the torsion vector and its derivatives. Assuming a purely radial torsion vector consistent with spherical symmetry, we derive two exact vacuum solutions. The metric depends on two integration constants, defining the Schwarzschild radius and a new cosmological-type length scale. Classical Solar System tests, inclu…

Read →
astro-ph.IM

Simulating Zernike-based CWFS with HCIPy

Klaus Subbotina Stephenson, Kate Jackson

This work explores optimal sensing distances in Zernike-based Curvature WaveFront Sensing (CWFS). By using HCIPy, an open-source Python package, we simulate the first 100 Zernike modes at a variety of propagation distances (1 to 20,000 m) to explore the relationship between the propagation of a wavefront and its spatial complexity to understand an idealized CWFS' sensitivity to individual modes. We find that there exist distinct optimal sensing distances for low-spatial-order-modes, with high-sp…

Read →
astro-ph.IM

Simulating Zernike-based CWFSing with HCIPy

Klaus Subbotina Stephenson, Kate Jackson

This work explores optimal sensing distances in Zernike-based Curvature WaveFront Sensing (CWFS). By using HCIPy, an open-source Python package, we simulate the first 100 Zernike modes at a variety of propagation distances (1 to 20,000 m) to explore the relationship between the propagation of a wavefront and its spatial complexity to understand an idealized CWFS' sensitivity to individual modes. We find that there exist distinct optimal sensing distances for low-spatial-order-modes, with high-sp…

Read →
astro-ph.IM

The Roman Coronagraph Community Participation Program: trials and triumphs of designing an observing program for a technology demonstration instrument

Schuyler G. Wolff, Vanessa P. Bailey, Justin Hom, Beth Biller, Dmitry Savransky, Julien H. Girard, Ellis Bogat, Óscar Carrión-González et al.

The Coronagraph Instrument onboard the Nancy Grace Roman Space Telescope serves as a crucial technology pathfinder for the Habitable Worlds Observatory, with on-sky verification of high-contrast imaging techniques and the potential to image a Jupiter analog in reflected light for the first time. Together with the Roman Project Team, the Community Participation Program (CPP) is responsible for target selection, preparatory observations, developing an exposure time calculator, target database, dat…

Read →
astro-ph.IMastro-ph.EPastro-ph.SR

The Roman Coronagraph Community Participation Program: pre-launch reference star list and impact of reference star properties on post-processing performance

Justin Hom, Schuyler G. Wolff, Jessica Gersh-Range, Ramya M. Anche, Vanessa P. Bailey, Jean-Philippe Berger, Beth A. Biller, Wolfgang Brandner et al.

The upcoming Roman Coronagraph will be the first high-contrast instrument in space capable of high-order wavefront sensing and control technologies, a critical technology demonstration for the proposed Habitable Worlds Observatory (HWO) that aims to directly image and characterize habitable exoEarths. The nominal Roman Coronagraph observing plan involves alternating observations of a science target and a bright, nearby reference star for both wavefront calibration and reference differential imag…

Read →
astro-ph.IM

pynucastro 3: A community library for nuclear astrophysics

Zhi Chen, Khanak Bhargava, Eric T. Johnson, Reth Lopes, Melissa Rasmussen, Alexander Smith Clark, Michael Zingale, Brendan Boyd et al.

We describe the latest release of pynucastro: a community python library for nuclear astrophysics. The goal of the pynucastro project is to build the tools needed to interactively explore nuclear properties, reaction rates, and networks, and to export these networks to a variety of simulation codes. Major changes in pynucastro since the last major release include new rate approximations, a stellar equation of state, support for the StarLib library and rate uncertainties, and new tools for explor…

Read →
astro-ph.IM

The Roman Coronagraph Community Participation Program: data reduction pipeline design and implementation

Jason J. Wang, Maxwell A. Millar-Blanchaer, Marie Ygouf, Julia Milton, Jürgen Schreiber, Kevin J. Ludwick, Ellis Bogat, Amanda Chavez et al.

The Roman Space Telescope Coronagraph Instrument will demonstrate a series of technologies and techniques to enable the direct detection of reflected-light planets with space-based observatories. To characterize and validate the performance of the Coronagraph Instrument, the Community Participation Program is developing corgidrp, an open-source Python-based data reduction pipeline. The pipeline can process data from the required and best-effort observing modes and their associated calibration se…

Read →
astro-ph.EPastro-ph.IM

Astro-Hunters: Machine Learning for Exoplanet Transit Detection in TESS Photometry

Fatimah Emad Eldin

Finding planets beyond the Solar System is now largely a data-analysis problem: photometric surveys return far more stellar light curves than can be inspected by eye, and machine learning is increasingly asked to recognise the faint, periodic dimming of a transiting planet. Whether such a detector works turns on a choice that is seldom reported: how its training labels were made. No catalogue disposes the individual measurements a per-cadence detector must classify, so the annotation has to be d…

Read →
astro-ph.HEastro-ph.GA

The X-Ray Continuum Emission Region in the Lensed Quasar SDSS J133907.23+131038.6 is Much Smaller than the Accretion Disk

Christopher W. Morgan, James B. Margeson, Gilberto Garcia, Xinyu Dai, Luis J. Goicoechea, Vyacheslav N. Shalyapin, George Chartas

We analyze microlensing variability in 15 seasons of optical monitoring data and 4 epochs of new X-ray observations of the doubly-imaged gravitationally lensed quasar SDSS J133907.23+131038.6 to place empirical constraints on the size and structure of that system's X-ray and optical continuum emission regions. Employing a Bayesian Monte Carlo method, we analyzed ground-based optical light curves to constrain the half-light radius of the far-UV source $\log(r_{\rm 1/2, FUV}/{\rm cm})=15.78^{+0.26…

Read →