UchUchU

Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.IM

COS2035: Extending COS/FUV Operations Through the 2030s

Marc Rafelski, David Sahnow, Christian I. Johnson, Bethan James, Svea Hernandez, John Debes, Beverly Serrano, Kate Davis et al.

The far-ultraviolet (FUV) detector of the Cosmic Origins Spectrograph (COS) accumulates gain sag where photons land, and without continued mitigation this degradation would render the most used modes unusable. To extend COS FUV operations through the 2030s, the COS team developed the COS2035 strategy, which builds on the existing COS2025 rules with four technical breakthroughs and two new usage policies. First, SPLIT-wavecals decouple wavelength calibration from science exposures and open detect…

Read →
astro-ph.GA

Efficient Interstellar Grain Growth from High Sticking Coefficients on Amorphous Carbon Dust

Clarke J. Esmerian, Duncan Bossion, Francois Dulieu, Saoud Baouche, Alexey Potapov, W. M. C. Sameera, Tom J. L. C. Bakx, Susanne Aalto et al.

Cosmic dust is the solid phase of the interstellar medium (ISM), classically assumed to be composed of carbonaceous and silicate grains with size distributions spanning $\sim 5~Å$ to $\sim 1~μ$m (Weingartner & Draine 2001, Draine & Li 2007, Hensley & Draine 2023). While it constitutes at most order-of-magnitude $\mathbf{1\%}$ of the ISM mass, dust is second only to stars in importance for the observable properties of galaxies (Zavala et al. 2021). Large uncertainties in the efficiency of grain g…

Read →
astro-ph.HEphysics.plasm-ph

Ultra-long simulations of collisionless relativistic shocks in front-comoving frame: evidence for a steady state and its properties

Mikhail Garasev, Evgeny Derishev

We present a series of unprecedently long 2D3V PIC simulations of unmagnetized relativistic $e^{-}e^{+}$-pair shocks performed in a front-comoving frame. By implementing a moving-wall boundary condition in the downstream together with continuous injection at the upstream boundary, we maintain a fixed simulation domain size, opening the way to perform substantially longer simulations. Our longest runs extend beyond $100000\,ω_p^{-1}$, exceeding the duration of the previously published simulations…

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

Hierarchical Three-Body Problem at High Eccentricities = Simple Pendulum, IV: Octupole for Librating Kozai-Lidov Cycles

Ygal Y. Klein

We solve analytically the long-term octupole evolution of \textit{librating} Kozai-Lidov cycles - those with a negative Kozai constant, in which the argument of pericenter librates - in the double-averaged restricted hierarchical three-body problem. Librating cycles reach extreme eccentricities when the normal component of the orbital angular momentum vanishes, just as rotating cycles do, but their slow dynamics was left unsolved: as noted by Katz, Dong \& Malhotra (2011), the azimuth of the ecc…

Read →
astro-ph.EP

The Expected Yield of Venus Zone Terrestrial Planets from PLATO

Stephen R. Kane, Emma L. Miles, Colby M. Ostberg, Erika Kohler, James B. Garvin

The characterization of terrestrial exoplanets and the conditions that lead to divergent climate outcomes is a primary goal of exoplanetary science. The Venus Zone (VZ) provides a framework for identifying planets that may have experienced runaway greenhouse processes similar to Venus, and the statistical properties of such planets bear directly on models of planetary habitability. Here we present a quantitative estimate of the expected yield of VZ terrestrial planets from ESA's PLATO (PLAnetary…

Read →
astro-ph.GA

Chemodynamical evidence of the HR 1614 moving group as a bar resonance

Andreas J. Koch-Hansen, Vladislav Gulaev, Dominik H. Plonka, Camilla Juul Hansen, Andrew McWilliam, Victor P. Debattista, Zdenek Prudil

Moving groups (MGs) are ensembles of disk stars that clump in velocity and action space. A multitude of explanations as to their origin has been attempted, from dissolved star clusters to resonances with the Galactic bar, or other non-axisymmetric perturbations. The object of this work, the old HR 1614 group, has in the past already been shown to not be a disrupted cluster in terms of its broad age and metallicity distribution. Thus its stars have more likely been trapped by the Milky Way bar at…

Read →
astro-ph.HE

Signatures of Black Hole Spin in Horizon-Scale Polarimetry

George N. Wong, Daniel C. M. Palumbo, Zachary Gelles, Andrew Chael

The angular momentum of a black hole, usually expressed in terms of a dimensionless "spin," both shapes the strong-field spacetime and provides a reservoir of rotational energy that can be exchanged with surrounding plasma. Very long baseline interferometry (VLBI) has now begun to resolve polarized emission on event-horizon scales. We distinguish polarimetric signatures of spin arising primarily from photon propagation in the Kerr spacetime from those mediated by horizon-threading electromagneti…

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

The topology of the magnetic field in Abell 2255 out to its virial radius. Results from the LOFAR Galaxy Cluster Ultra-Deep Field

A. Botteon, R. J. van Weeren, Y. Hu, F. Vazza, G. Brunetti, K. Rajpurohit, A. Lazarian, T. W. Shimwell et al.

We present the LOFAR Galaxy Cluster Ultra-Deep Field, in which 336 h of LOFAR observations at 120$-$168 MHz have been collected on the nearby ($z=0.080$) cluster Abell 2255. This massive and merging system is known to host spectacular radio emission from both cluster galaxies and the intracluster medium. Previous LOFAR observations revealed pervasive diffuse synchrotron emission extending from the cluster center to its dynamically active outskirts, tracing relativistic electrons propagating in l…

Read →
astro-ph.SRastro-ph.GA

The Open Cluster Chemical Abundances and Mapping Survey: IX. Measuring the Effects of Stellar Diffusion in the Open Clusters NGC 752 and Ruprecht 147 using APOGEE

Diogo Souto, Taylor Spoo, Peter M. Frinchaboy, Katia Cunha, Jamie Tayar, Alessa Ibrahim Wiggins, Natalie Myers

A growing understanding of stellar processes that alter surface chemical abundances over time has opened new avenues for using these changes as probes of stellar properties. On the main sequence and near the turnoff, stellar surface abundances are affected by gravitational settling and radiative acceleration, collectively known as atomic diffusion. In this work, we use SDSS/APOGEE DR17/DR19 data to investigate atomic diffusion in the open clusters NGC~752 and Ruprecht~147, thereby constraining h…

Read →
astro-ph.COastro-ph.GA

Measuring satellite galaxy subhalo masses in redMaPPer clusters with UNIONS weak lensing data

Roman Akhmetshyn, Jack Elvin-Poole, Michael J. Hudson, Isaac Cheng, Thomas de Boer, Sébastien Fabbro, Sam Farrens, Sacha Guerrini et al.

In this work, we present the observed galaxy-galaxy lensing signal of satellite galaxies in rich clusters obtained from the Ultraviolet Near-Infrared Optical Northern Survey (UNIONS). Such observations are crucial for understanding dark matter halo physics and interaction dynamics in the cluster environment. Our goal is to investigate the tidal stripping of cluster subhalos. Theoretical predictions, supported by recent studies, suggest that as satellite galaxies fall into clusters, their dark ma…

Read →
astro-ph.GA

Cold Stream Penetration of Virial Shocks: Fragmentation, Coagulation, and Disruption in the Hot Circumgalactic Medium

Zhiyuan Yao, Nir Mandelker, S. Peng Oh

Cold streams penetrating virial shocks of massive halos along cosmic web filaments are expected to fuel galaxy growth at high redshift, yet the physical processes governing their penetration remain uncertain. We investigate cylindrical cold streams penetrating a hot circumgalactic medium (CGM) using idealized three-dimensional simulations. We systematically vary the stream radius, Mach number, and initial pressure contrast between the stream and the CGM across three density contrasts, while cont…

Read →
astro-ph.GAastro-ph.CO

Investigating anomalous microwave emission near G107.2+5.20 in Ku-band with the Green Bank Telescope

Jordan E. Shroyer, Bradley R. Johnson, Dillon J. Bass, L. Ilsedore Cleeves, Anna Dignan, Stuart E. Harper, Brian S. Mason, Andrey Moore et al.

Anomalous microwave emission (AME) is 30 GHz-peaking continuum emission thought to arise from spinning dust grains. Observations suggest that the local environment shapes the AME spectral energy distribution (SED), so building a spatially resolved sample of AME regions is a key step towards understanding its emission mechanism. Using the Green Bank Telescope Ku-band receiver, we obtained a ~1 arcmin resolution map of radius 1.25 deg centered on G107.2+5.20. Our first objective was to constrain t…

Read →
gr-qcastro-ph.HEhep-th

Entropy release from Minkowski breaking in regular Schwarzschild black holes

Francisco S. N. Lobo, Manuel E. Rodrigues

The classical formation of a Schwarzschild black hole from a regular, non-singular configuration has recently been shown to be impossible within general relativity: the geometry inevitably develops a discontinuity at the origin, a phenomenon termed Minkowski breaking by Ovalle, Casadio, and Kamenshchik [PRD 113 (2026), 064042]. This obstruction signals that the transition to the Schwarzschild point mass must be a discrete, quantum event. We uncover the thermodynamic footprint of this transition.…

Read →
astro-ph.GA

Magnesium isotope ratios in Milky Way and dwarf galaxy stars

M. McKenzie, S. Monty, D. Yong, C. Kobayashi, A. I. Karakas, P. E. Nissen, J. E. Norris, A. Rains et al.

Under the assumption of hierarchical galaxy formation, dwarf galaxies are the closest existing analogues to the high-redshift protogalaxies that merged to form the Milky Way. These low-mass systems serve as unique laboratories for studying nucleosynthetic channels, given that the chemical compositions of their stars play a pivotal role in constraining their chemical enrichment history. To date, stellar abundances in dwarf galaxies have focused almost exclusively on elemental abundance ratios. Wh…

Read →
astro-ph.GA

The complex stellar system M 22: constraining the chemical enrichment from AGB stars using magnesium isotope ratios

M. McKenzie, D. Yong, A. I. Karakas, E. Wang, S. Monty, A. F. Marino, A. P. Milone, T. Nordlander et al.

The complex star cluster M 22 (NGC 6656) provides a unique opportunity for studying slow neutron-capture (s-process) nucleosynthesis at low metallicity due to its two stellar groups with distinct iron-peak and neutron-capture element abundances. Previous studies attribute these abundance differences to pollution from 3-6 solar-mass asymptotic giant branch (AGB) stars, which produce significant quantities of the neutron-rich Mg isotopes 25Mg and 26Mg. We report the first-ever measurements of Mg i…

Read →
astro-ph.GA

The complex stellar system M 22: confirming abundance variations with high precision differential measurements

M. McKenzie, D. Yong, A. F. Marino, S. Monty, E. Wang, A. I. Karakas, A. P. Milone, M. V. Legnardi et al.

M 22 (NGC 6656) is a chemically complex globular cluster-like system reported to harbour heavy element abundance variations. However, the extent of these variations and the origin of this cluster is still debated. In this work, we investigate the chemical inhomogeneity of M 22 using differential line-by-line analysis of high-quality (R = 110,000, S/N = 300 per pixel at 514 nm) VLT/UVES spectra of six carefully chosen red giant branch stars. By achieving abundance uncertainties as low as ~0.01 de…

Read →
physics.hist-phastro-ph.EP

The orientation of the Amazonian geoglyphs as a clue for their interpretation

Giulio Magli

Amazonian earthworks, also called geoglyphs, are thousands of man-made earthen structures, mostly of geometrical shape, which progressively emerged from the tropical forest due to progressive deforestation. They were probably built between the fifth century BC and the end of the first millennium AD, but archaeological investigation on the culture of their builders is yet at the beginning. Nevertheless, a ceremonial rather than practical function seems likely, at least for those having a very reg…

Read →
astro-ph.IM

Update on the Magellan InfraRed Multi-Object Spectrograph (MIRMOS)

Maren Cosens, Nicholas P. Konidaris, Gwen C. Rudie, Andrew B. Newman, Leon Aslan, Robert Barkhouser, Christoph Birk, Julia Brady et al.

The Magellan InfraRed Multi-Object Spectrograph (MIRMOS) will be a next generation multi-object (MOS) and integral field spectrograph (IFS) for the 6.5m Magellan telescopes at Las Campanas Observatory in Chile. MIRMOS will perform R~3700 spectroscopy over a simultaneous wavelength range of 0.886-2.404um (Y, J, H, and K bands) in addition to imaging over the range of 0.7-0.886um. Target selection in the MOS mode is achieved through a cryogenic mechanism capable of making up to 92 slits over a 13'…

Read →
astro-ph.IM

Update on the slicer IFU for the Magellan InfraRed Multi-Object Spectrograph (MIRMOS)

Maren Cosens, Patricio Schurter, Nicholas P. Konidaris, Gwen C. Rudie, Andrew B. Newman, Leon Aslan, Robert Barkhouser, Christoph Birk et al.

The Magellan InfraRed Multi-Object Spectrograph (MIRMOS) is a planned next generation multi-object and integral field spectrograph for the 6.5m Magellan telescopes at Las Campanas Observatory in Chile. MIRMOS will perform $\rm R\sim3700$ spectroscopy over a simultaneous wavelength range of 0.886 - 2.404um (Y, J, H, K bands) in addition to imaging over the range of 0.7 - 0.886um. The integral field mode of operation for MIRMOS will be achieved via an image slicer style integral field unit (IFU) l…

Read →
astro-ph.SR

Observational Evidence for Counter-helicity Magnetic Reconnection in a Solar Eruption

Jinrui Chang, Yi Bi, Bo Yang, Junchao Hong, Jiayan Yang, Qingmei Wang

Magnetic reconnection between coronal magnetic systems carrying opposite self-helicity may play a role in solar eruptions, but observational evidence remains limited. We investigate an M7.0 flare in NOAA Active Region 13615 on 2024 March 28 using multiwavelength observations and nonlinear force-free field extrapolations. The reconstructed coronal field reveals a low-lying positive-helicity core field beneath an overlying magnetic system of opposite sign. During the eruption, the footpoint connec…

Read →
astro-ph.IM

Development and characterization of a millimeter-wave cold load prototype

Ruya Cong, Junjie Zhou, Yu Xu, Xuefeng Lu, Jianrong Cai, Haoxuan Gao, Kang Zhang, Xingyuan Hou et al.

Superconducting transition-edge sensors (TESs) are crucial detectors for cosmic microwave background (CMB) observations and require stable and tunable millimeter-wave cold loads for optical-efficiency calibration. This work presents the design, fabrication, and preliminary characterization of a 4-20 K millimeter-wave cold load prototype intended for integration into the 1 K stage of a dilution refrigerator and subsequent 40/90 GHz CMB TES calibration experiments. Two absorber prototypes based on…

Read →
astro-ph.IM

phoptic -- a Python package for reducing astronomical images

Zackery A. Irving, Noel Castro Segura, Diego Altamirano, Federico Vincentelli, Angel Castro, Romina P. Petrucci, Raul Michel, Adam B. Hill et al.

Publicly-available photometry pipelines make astronomical data reduction accessible to non-experts, reduce the margin for human error, and enable reproducible reduction. In many cases, bespoke reduction software is written on a per-instrument basis; this results in rigid pipelines that cannot be straightforwardly applied to data from other instruments. To alleviate this problem, we present phoptic, an open source photometry pipeline written in Python. phoptic began as a dedicated pipeline for th…

Read →
astro-ph.SRastro-ph.GA

The potential broader complex linked to the key Cepheid SV Vul

Daniel Majaess, Ignacio Negueruela, Leonid N. Berdnikov, Charles J. Bonatto, David G. Turner, Dante Minniti, Vittorio F. Braga, Giovanni Carraro et al.

A new distance was established to the Cepheid SV Vul ($P\simeq45^{d}$) and its host cluster Alicante 13, and is tied in part to deeper UKIDSS-DR6 photometry and Gaia DR3 observations ($d=2.30\pm0.13$ kpc). SV Vul and Alicante 13 possibly belong to a broader coeval stellar complex, which could include Liu-Pang 1738. The clusters and Cepheid share comparable astrometry (e.g., $σ_π\simeq0.02$ mas, $σ_{μ_δ}\simeq0.06$ mas yr$^{-1}$), and similar cluster turnoffs (ages) exist as indicated by ultravio…

Read →
gr-qcastro-ph.HE

DARK-HIDE: Dark matter versus hidden dimensions in black hole images

Mohsen Fathi

Dark matter near a black hole and effective extra-dimensional corrections can change the same horizon-scale observables. This creates a simple but important question: if an image differs from Kerr, what caused the difference? We study this problem with DARK-HIDE. The dark-matter branch is described by rotating metrics with radial mass functions, while the hidden-dimensional branch is a rotating braneworld metric with a non-electromagnetic tidal charge. We compare photon regions, critical curves,…

Read →
astro-ph.HEhep-phhep-th

The Origin of Multi-TeV Gamma-rays in LHAASO J0341+5258 via Cosmic Ray Illumination of Molecular Clouds

Abhijit Roy, Alan Sunny, Martina Cardillo, Jagdish C. Joshi, Ritabrata Sarkar

We investigate the origin of the ultra-high-energy $γ$-ray emission detected by the Large High Altitude Air Shower Observatory (LHAASO) from the source LHAASO J0341+5258, which has not yet been associated with any known astrophysical object within the detector's field of view. The observed UHE emission is modelled within two independent frameworks: initially with a time-dependent, source-independent hadronic scenario implemented with the numerical package GAMERA, where particles propagate throug…

Read →
astro-ph.COastro-ph.GA

A Universal Relation Between Primordial Density-Potential Cross-correlation Coefficient and Spin Factor Distribution

Jun-Sung Moon, Jounghun Lee, Juhan Kim

Recent studies have revealed that the key properties of visible galaxies like their optical sizes, stellar ages, star formation rates and morphologies are closely linked with the angular momenta of their host dark matter halos. According to the linear tidal torque theory, the halo angular momentum, as a conserved quantity, is directly proportional to the primordial spin factor, $τ$, defined as the degree of misalignment between the principal axes of the initial density and potential Hessian matr…

Read →
astro-ph.GA

Even central galaxies feel their environment: cosmic siphoning of cool gas accretion

Ke Xu, Tao Wang

Identifying the key processes regulating cool gas accretion in galaxies is essential for understanding the baryon cycle within galactic ecosystems. Recent studies indicate that the most fundamental internal process is likely the competition between halos and central black holes. This is revealed through a universal relation between increasing black hole masses and decreasing cool gas fraction ($μ_{\rm HI} \equiv M_{\rm HI}/M_{\star} \propto M_{\rm BH}^{-0.6}$). Here we further explore the primar…

Read →
cs.CVastro-ph.IM

PlumeQuant: Uncertainty-aware consistency assessment of methane plume masks and emission-rate estimates

Parisa Masnadi Khiabani, Wolfgang Jentner, Alireza Rangrazjeddi, Michael C. Wimberly, Binbin Weng, David Ebert, Charles Nicholson

Imaging spectrometers increasingly distribute source-resolved methane plume products in which the plume mask, integrated mass enhancement (IME), plume length, emission rate, and uncertainty are physically and algorithmically linked. Using 63 EMIT-derived Carbon Mapper plume records from 27 scenes, we show that these published scalar quantities do not uniquely constrain the plume boundary: substantially different yet plausible masks reproduce the same IME, plume length, and emission rate. Genetic…

Read →
astro-ph.GA

The dynamical environment of the high-mass star-forming region G28.288$-$0.364

Jyotirmoy Dey, Devendra K. Ojha, Jagadheep D. Pandian

Massive stars form within deeply embedded dust cores, and the development of hypercompact and ultracompact H II regions characterizes their early evolution. Identifying and analyzing such regions is essential for understanding the physical processes that govern massive star formation and the transitions between early evolutionary stages. In this article, we investigate the physical and kinematic properties of the massive star-forming region G28.288$-$0.364 to constrain the evolutionary stages of…

Read →
nucl-thastro-ph.HEphysics.comp-ph

NNStar: An end-to-end AI agent for nuclear matter and neutron star physics

Yao Ma, Yong-Liang Ma, Jia-Ying Xiong

Constraining the equation of state of dense matter requires confronting effective models with massive data that spans many orders of magnitude in scale, from sub-saturation nuclear matter properties to the masses, radii, and tidal deformabilities of neutron stars. Exploring the high-dimensional coupling space of such a model and fine tuning it against all of these constraints is a labor- and time-intensive task. We present \textsc{NNStar}, an end-to-end artificial-intelligence agent that automat…

Read →