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Research Trends

Latest preprints in space engineering and astrophysics.

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…

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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…

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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.…

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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…

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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…

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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…

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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…

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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'…

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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…

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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…

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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…

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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…

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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…

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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,…

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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…

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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…

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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…

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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…

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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…

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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…

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astro-ph.SRastro-ph.HEphysics.space-ph

Long-Baseline VLF Observations of Solar Flares from Antarctica

Kamen Kozarev, Peter Petkov, Ivaylo Nachev, Veselka Radeva, Momchil Dechev, Galin Borisov, Anton Atanasov

We present long-baseline Very Low Frequency (VLF) observations of solar flare-induced ionospheric disturbances obtained at the Bulgarian Polar Astronomical Observatory (St. Kliment Ohridski Base) on Livingston island, Antarctica. Using continuous VLF transmissions at 21.4 kHz (NPM, Hawaii) and 24.0 kHz (NAA, Maine), propagating over trans-hemispheric paths exceeding 11000 km, we analyze observations of solar flares during the period 24 January--8 February 2025. After removing the strong diurnal…

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astro-ph.SR

A Homogeneous Spectroscopic and Evolutionary Study of cool HgMn and hot Metallic A Stars

F. Kahraman Aliçavuş, E. Çelik, E. Niemczura

We present a homogeneous spectroscopic and evolutionary analysis of chemically peculiar stars, focusing on HgMn and metallic A (Am) subclasses. Particular emphasis was placed on the coolest HgMn stars and the hottest Am stars, motivated by the long-standing hypothesis that these objects may represent consecutive evolutionary stages of a similar stellar population. High-resolution spectra of 13 HgMn and 14 Am targets were analyzed to derive atmospheric parameters and detailed chemical abundances.…

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astro-ph.GA

Mapping Dust Attenuation at Kiloparsec Scales. IV. A Dust-model Interpretation of Attenuation Curves in Nearby Galaxies

Ruonan Guo, Cheng Li, Tao Jing, Shuang Zhou, Niu Li, Zhuo Cheng

In this fourth paper on kiloparsec-scale dust attenuation, we ask whether the empirical trends found in Papers I--III can be translated into effective dust properties. Using attenuation curves for 2487 high-continuum-S/N spaxels in 91 SwiM v4.2 galaxies, we construct a grid of uniform-screen dust models composed of astronomical silicate and graphite grains with MRN-like size distributions. We fit the normalized attenuation-curve shape to constrain model parameters and then use the attenuation am…

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astro-ph.SRastro-ph.EPastro-ph.GAastro-ph.IM

Cradle of Life: From the Formation of Stars to Habitable Worlds with the SKAO

Eleonora Bianchi, Joseph R. Callingham, the Cradle of Life working group

This chapter provides an overview of the different science cases covered by the "Cradle of Life" working group, which aims to leverage the capabilities of the Square Kilometre Array Observatory (SKAO) to trace the physical and chemical pathways toward stars and planets formation, how such stars impact their planets, and whether life could exist in such conditions. At its highest frequencies, the SKAO will probe the earliest stages of the raw material fuelling planet formation, while enabling dee…

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astro-ph.IM

Fabrication of focusing optics for TA-MOONS: Micro-MOONS

Ceiwynn Longworth, Megan Delamer, Suvrath Mahadevan, Joe P. Ninan, Kathleen Gehoski, Krushna Jadhav

Understanding star and planet formation requires optical to near-infrared spectroscopic observations of a large number of young stellar objects. The TIFR-ARIES Multi-Object Optical to Near-infrared Spectrometer's (TA-MOONS) primary objective is to preform a large spectroscopic survey of young stellar objects across wavelengths of 360 nm to 2.5 microns, with the multiplexed capability of observing up to eight sources simultaneously. Multiplexity is achieved by moving pickup mirrors on robotic arm…

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astro-ph.SRastro-ph.IM

The SKA as a Probe of Heliospheric Turbulence and Radio-wave Propagation Effects

Nicolina Chrysaphi, Eduard P. Kontar, Hamish A. S. Reid, Sophie Musset, Shilpi Bhunia, Kamen Kozarev

Density turbulence in the heliosphere can impact traversing radio photons originating from anywhere in the universe, leading to distortions of both the spectroscopic and imaging properties of the radio sources. Extra-solar radio sources exhibit scintillation and angular broadening, while monochromatic signals from spacecraft are spectrally broadened. It was recently demonstrated that such impacts, referred to as radio-wave propagation effects, are particularly significant in observations of sola…

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astro-ph.EP

Reflation: redox-driven atmospheric inflation as tracer of super-Earth geochemistry

Lorenzo Cesario, Tim Lichtenberg, Mara Attia, Harrison Nicholls, Imre Kisvardai, Quentin Changeat

We demonstrate that the redox-sensitivity of mantle outgassing can trigger transient episodes of atmospheric re-inflation in highly irradiated and geochemically-reduced super-Earths, a mechanism we term reflation. Mantle redox governs the outgassing and speciation of CHONS volatiles, setting the background secondary atmospheric composition during extended photoevaporation at highly irradiated conditions. Using simulations of the coupled atmosphere-interior evolution of irradiated super-Earths, w…

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astro-ph.GA

RABBITS IV: Stellar feedback and SMBH merging time-scales in the sub-Milky Way mass regime

Ruby J. Wright, Roosa Heiskanen, Shihong Liao, Alexander Rawlings, Peter H. Johansson, Max Mattero, Fiona H. Panther, Atte Keitaanranta et al.

Merging supermassive black holes (SMBHs) in low- and intermediate-mass galaxies are important sources for future millihertz gravitational-wave observatories such as LISA. Predicting the delay between galaxy coalescence and SMBH merger is therefore critical for modelling the observable SMBH merger population. Using the KETJU code, we perform 16 equal-mass galaxy merger simulations as part of the Resolving supermAssive Black hole Binaries In galacTic hydrodynamical Simulations (RABBITS) series to…

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astro-ph.SR

Unveiling the nature of G6096: a likely hierarchical triple system

Yinghao Xu, Xinlin Zhao, Song Wang, Guang-Yao Xiao, Zikun Lin, Xue Li, Hao-Bin Liu, Henggeng Han et al.

G6096 (Gaia DR3 609651611028044544) was recently reported as a wide ($P\sim 450$ days) and eccentric ($e\sim0.18$) binary possibly hosting a massive white dwarf or neutron star. In this work, through analyses of the projected rotational velocity between the blue and red bands, spectral disentangling, joint radial velocity and astrometric fitting, and X-ray emission, we suggest that the system contains additional visible component(s) rather than a compact object. We develop a new approach to reve…

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hep-phastro-ph.HEgr-qc

High-Energy Neutrinos from Black Hole Evaporation in Neutron Stars

Ioannis Dalianis

We investigate the production of high-energy neutrinos from microscopic black holes formed through the gravitational collapse of asymmetric dark matter accumulated inside neutron stars. When Hawking evaporation dominates over accretion, long-lived, feebly interacting particles beyond the Standard Model escape the neutron star and subsequently decay into high-energy neutrinos. We analyze the repeated cycle of dark matter capture, black hole formation, and evaporation, identifying two distinct reg…

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