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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.IMeess.SP

Radio Interferometric Calibration with the Exponential Map

L. Cabral, M. Fernandez-Corazza, G. Gancio, P. Benaglia

The antenna-elements that make up a radio interferometer form a spatial filter that samples components of the Fourier transform of a target radio astronomical source brightness. Along the signal path, there are multiplicative and additive perturbation effects that alter the signal and that should be corrected. The process of mitigating these perturbation effects is called calibration. In this work, we develop a new and fast Maximum Likelihood based estimator of these perturbation effects using t…

astro-ph.HE

Recycling serendipitous observations of XRISM for dark matter searches

Lidiia Zadorozhna, Denys Malyshev, Oleg Ruchayskiy

Searches for radiative decays of keV-mass dark matter have been limited by energy resolution. We propose a strategy for the XRISM/Resolve low count rate observations, and search the 3.48-3.56 keV band for a decay line from the Milky Way halo. Despite a lower exposure, our bounds are stronger than those from XRISM observations of galaxy clusters. We also identify a residual at E = 3.5311 keV with ~3sigma local significance, coincident with the previously reported unidentified feature, and having…

astro-ph.IMastro-ph.CO

hyprfine: simulating the 21-cm signal from the Dark Ages through to the Epoch of Reionization on a GPU

Harry T. J. Bevins

hyprfine is an analytic simulation of the sky-averaged 21-cm signal from $z=1100 - 6$ written using JAX and Python for native GPU capabilities. It models the average temperature of the 21-cm signal over cosmic time as a function of the $Λ$-CDM cosmology parameters and the astrophysics of the first stars and galaxies. As far as we are aware, the code is the first analytic GPU native simulation of the 21-cm signal. It runs in a fraction of a second, parallelises efficiently across a GPU and is dif…

astro-ph.IMastro-ph.CO

hyprfine: simulating the 21-cm signal from the Dark Ages through to the Epoch of Reionization on a GPU

Harry T. J. Bevins

hyprfine is an analytic simulation of the sky-averaged 21-cm signal from $z=1100 - 6$ written using JAX and Python for native GPU capabilities. It models the average temperature of the 21-cm signal over cosmic time as a function of the $Λ$-CDM cosmology parameters and the astrophysics of the first stars and galaxies. As far as we are aware, the code is the first analytic GPU native simulation of the 21-cm signal. It runs in a fraction of a second, parallelises efficiently across a GPU and is dif…

astro-ph.HE

Slingshot on compact binaries in the nuclear region of galaxies as the origin of large offset gamma-ray bursts

Juan C. Rodríguez-Ramírez, Viviane Alfradique, Clécio R. Bom, Davi C. Rodrigues

A growing number of gamma-ray bursts (GRBs) have been observed at large projected offsets from the centres of their putative host galaxies, sometimes extending to several tens of kiloparsecs. When the GRB is associated with a kilonova, a compact binary with at least one neutron star is expected to be involved, and the cause of the offset can be attributed to the neutron star natal kick. In this work, we explore an alternative mechanism: the gravitational scattering of compact binaries populating…

astro-ph.GA

Diverse Protoclusters at $z\sim3$ Disclosed by Systematic Spectroscopy

Jun Toshikawa, Kentaro Koretomo, Nobunari Kashikawa, Stijn Wuyts, Marcin Sawicki, Malcolm N. Bremer, Yoshiaki Ono, Mariko Kubo et al.

We present the results from follow-up spectroscopy of three protocluster candidates at $z\sim3$, selected as overdense regions of $U$-dropout galaxies in the wide-field imaging of the Hyper SuprimeCam Subaru Strategic Programme. All three targets exhibit tight clustering in three-dimensional space, i.e. on the sky ($>4σ$ overdensity) and in redshift ($>98.4\%$ confidence), making for clear evidence of genuine protoclusters. Since these three protoclusters are identified by the same dataset and t…

astro-ph.GA

Galaxy Protoclusters as Drivers of Cosmic Reionization: II. Te-Based Metallicities of Lyman-α Emitters

C. Moya-Sierralta, C. L. Martin, L. F. Barrientos, L. Infante, J. González-López, W. Hu, A. L. Faisst, Y. Harikane et al.

Context. Protoclusters at reionization are thought to host a significant fraction of the cosmic star formation rate density, making them crucial for the timing and topology of reionization. The gas-phase metallicity, a key tracer of galaxy evolutionary stage, can now be measured directly in the early Universe with JWST. Aims. We measure the gas-phase metallicity of Lyman-$α$ emitters (LAEs) in the LAGER-z7OD1 protocluster at $z\approx6.93$ via the direct ($T_e$-based) method using the [O III]$λ$…

astro-ph.EPcond-mat.mtrl-sci

Pressure-induced desalting of NaCl-bearing ice VII: A compositional filter in water-rich planets

Alasdair Nicholls, Tomasz Poreba, Xi Zhu, Richard Gaal, Stefan Klotz, Gabriel Tobie, Henrik M. Ronnow, Razvan Caracas et al.

Sodium chloride is a major component of extraterrestrial oceans, but it is generally assumed to be excluded from the high-pressure ice mantles of water-rich planets. Here we show that a concentrated NaCl solution, when quenched in an amorphous state before compression, crystallises in a metastable NaCl-bearing ice VII phase. Synchrotron x-ray diffraction and neutron diffraction reveals an expanded and strongly disordered ice VII lattice with no detectable crystalline NaCl. Ab initio calculations…

astro-ph.SR

Ensemble pulsational characteristics of eclipsing binaries containing $β$ Cep stars observed by the TESS mission

C. I. Eze, G. Handler, M. Vanrespaille, A. Kemp, A. Tkachenko, D. M. Bowman, C. Aerts

Massive pulsators in eclipsing binaries provide precise, model-independent stellar parameters that, combined with asteroseismic constraints, provide powerful probes of interior properties and angular-momentum transport in massive stars. This study investigates the pulsational characteristics and their impact on the structure and evolution of $β$ Cep pulsators in eclipsing binaries. We analyse an ensemble of 65 $β$ Cep stars in eclipsing binaries, identify rotationally split modes where possible,…

astro-ph.SR

Delayed, Line-dependent Reorganization of Pore Oscillations Following a Compact C8.2 Flare Observed by Sunrise III/SUSI

Shahin Jafarzadeh, David B. Jess, Marco Stangalini, Lyndsay Fletcher, Ryan O. Milligan, Paulo J. A. Simões, Peter H. Keys, Sami K. Solanki et al.

Magnetic oscillations permeating the solar atmosphere can be altered by flares. This could be due to changes in the atmospheric magnetic waveguide, the thermodynamic stratification, or both. To investigate this, we examine oscillations in a magnetic pore crossed in part by the ribbon of a C8.2 flare, using observations from the Sunrise Ultraviolet Spectropolarimeter and Imager (SUSI) aboard Sunrise III. We track the core intensities of eight spectral lines between 327-329 nm and show that oscill…

astro-ph.GAastro-ph.CO

Weighing Galaxies Inside-Out: Small-Scale Lensing and the Stellar Mass Problem

Divya Rana, Henk Hoekstra, Konrad Kuijken, Alessandro Sonnenfeld, Maryam Tajalli

Small-scale galaxy-galaxy weak lensing provides an independent way to probe the stellar initial mass function by constraining the matter distribution within galaxies. We forecast the potential of upcoming \textit{Euclid} observations using realistic mock catalogues designed for a DESI-like Bright Galaxy Survey, which is expected to cover approximately $9000\,\mathrm{deg}^2$ of the \textit{Euclid} wide survey area. We assess the impact of foreground lens light, which introduces significant scale-…

astro-ph.EPastro-ph.IM

Constraining Particle Stiffness in Asteroid Regolith from Early-Time High-Speed Penetrator Dynamics under Local Granular Variability

Zichen Wang, Yang Yu, Chenyang Huang, Zhijun Song, Yutian Wu, Xiaojing Zhang, Xuhui Zhang

Mechanical properties of rubble-pile asteroid regolith remain poorly constrained because contact responses depend on both material properties and local particle configuration. This study examines whether early-time high-speed penetrator dynamics can constrain particle stiffness, represented by the particle Young's modulus E, within a controlled discrete-element model. A bidirectionally coupled EDEM-Adams discrete-element-multibody model is used to screen six parameters: Young's modulus, Poisson'…

astro-ph.HE

Disk-Like Matter Outflow from a Kerr-Type Wormhole: Possible Observational Manifestations and Magnetic Effects

Mikhail Piotrovich, Stanislava Buliga, Tinatin Natsvlishvili

We present a phenomenological study of a hypothetical compact object with a traversable 2 Kerr-type wormhole geometry connecting two asymptotically distinct regions. One mouth of the wormhole is assumed to reside in an active galactic nucleus (AGN) environment with ongoing accretion, while the second mouth is located in a comparatively quiescent galactic nucleus without accretion activity. In such a configuration, matter accreted near the AGN-side mouth may traverse the wormhole throat and emerg…

astro-ph.GA

Constraining the density distribution of the cold Circumgalactic Medium of quasars at z>2 through Lya, HeII and Ha emission

Andrea Travascio, Sebastiano Cantalupo, Titouan Lazeyras, Naveen A. Reddy, Charles C. Steidel, Yongming Liang, Gabriele Pezzulli, Massimo Gaspari et al.

Extended Lya emission is routinely detected around high-redshift quasars, revealing large reservoirs of cool circumgalactic medium (CGM). Its resonant nature complicates interpretation of gas density, ionization state, and kinematics, making non-resonant tracers such as HeII and Ha essential. Extending previous analytical models, we use CLOUDY photo-ionization simulations to predict HeII/Ha in quasar-illuminated gas over a broad parameter range, including log-normal density distributions. The ra…

astro-ph.HEastro-ph.GA

Detection of kilosecond hard lags in the new pulsating ULX candidate NGC 7456 ULX-1

W. Leone, F. Pintore, C. Pinto, N. O. Pinciroli Vago, A. Sanna, A. Wolter, T. Di Salvo, R. Iaria et al.

Context. Ultraluminous X-ray sources (ULXs) are thought to be powered, in many cases, by super-Eddington accretion onto compact objects. While soft X-ray lags have been detected in several ULXs, hard lags remain rare and poorly understood. Aims. We investigate the temporal and energy dependence of X-ray lags in NGC 7456 ULX-1 to constrain their physical origin and probe the super-Eddington accretion flow. Methods. We analyzed the two deepest XMM-Newton observations, taken in 2018 and 2023. Hard…

astro-ph.GA

Resolving the physics of Quasar Ly$α$ Nebulae (RePhyNe): II. The dense and clumpy CGM of Quasars at $z \sim$ 3.5

Titouan Lazeyras, Sebastiano Cantalupo, Andrea Travascio, Nicolas Ledos, Joop Schaye, Gabriele Pezzulli, Federico Baraggioni, Alessandro Lupi et al.

The small scale density distribution of the cold circumgalactic medium (CGM) plays a central role in galaxy evolution, yet it is still poorly understood. We provide new constraints on the cold CGM density distribution by comparing the CGM emission from MUSE observations of quasar (QSO) nebulae at $z \sim 3.8$ with mock observations generated from the new DaLya simulation suite under the assumption of maximal fluorescence. These are further complemented by mock observations generated from the COL…

astro-ph.SRastro-ph.HEastro-ph.IM

Solarprop 2.0: Modern charge-sign dependent solar modulation for everyone

Henning Gast

I present a greatly improved version of SOLARPROP, an open source framework for building models of charge-sign dependent solar modulation of cosmic rays in the heliosphere. The transport equation of charged particles is solved by converting it to a set of stochastic differential equations (SDEs). The code now includes the full set of SDEs in two spatial dimensions, allowing for magnetic fields with latitudinal components, and it has been generalized to accommodate models in three spatial dimensi…

astro-ph.IM

Comment on: "The Preprint Evolution: The Rise of Unreviewed Drafts on arXiv and its Implications for Astronomy"

Noam Soker

I argue against the proposal of arXiv:2609.35787 to divide arXiv astrophysics submissions into two streams: peer-reviewed papers and pre-review discussion drafts. I contend that such a division would threaten open scientific discussion and could lead to increasingly restrictive categories based on journal impact factor or mainstream versus non-mainstream papers. Instead, readers who want only peer-reviewed work can use AI or other tools to filter papers, while others can continue monitoring the…

physics.ins-detastro-ph.GA

State of the Art in Direct Dark Matter Detectors: Technologies, Performance, and Future Directions

Muad Ghaith, Khaled Obaideen

Identifying the particle nature of dark matter remains one of the most significant challenges in modern physics. Direct detection experiments aim to observe rare scattering events between dark matter particles and terrestrial targets, a task that demands extreme background suppression and sensitivity to minute energy depositions. This review critically assesses the current experimental landscape, organizing detector technologies by the fundamental physical trade-offs that define their scientific…

astro-ph.SRmath-phphysics.ins-det

Towards solar many-line inversions

Johannes Hölken

The Sun's atmosphere is significantly influenced by events that often measure only tens of kilometres in the horizontal direction. They happen in both quiet and active regions and are determined by magneto-hydro-dynamic processes. Their origins often lie in the lowest layers of the solar atmosphere. To improve the understanding of chromospheric and coronal heating, the solar dynamo and its activity cycle, or to improve the prediction of space weather events we must therefore enhance our understa…

astro-ph.SRastro-ph.HE

Structure of Convective-Reactive Zone in a Supernova Progenitor

M. Mocak, C. Meakin, F. Rizzuti, S. W. Campbell, V. Varma, R. Hirschi, C. Georgy, W. D. Arnett et al.

Convective-reactive events are phases of stellar evolution where turbulent mixing and nuclear burning directly compete, since their timescales become similar within convection zones. During these events the convection zone structure is shaped by a complex and dynamic interaction of convective transport and nuclear burning of individual chemical elements, with plasma streams connecting the entrainment regions with the burning layers. Here we analyse a 3D hydrodynamic simulation of an oxygen--neon…

astro-ph.SR

Probing Accretion and Outflow in V1180 Cas through High-Resolution Optical Spectroscopy

Tarak Chand, Saurabh Sharma, Koshvendra Singh, Joe P. Ninan, Arpan Ghosh, Devendra K. Ojha, Jyotirmoy Dey, Manojit Chakraborty et al.

We present an analysis of a high-resolution optical spectrum of V1180 Cas obtained with HIRES at the W. M. Keck Observatory during a bright photometric state of the source. The spectrum is dominated by strong emission lines, including H$α$, the Ca II infrared triplet, He I, and O I, along with numerous Fe I and Fe II transitions and several forbidden lines such as [O I] and [S II], indicating ongoing accretion and mass-loss activity. A weak Li I $λ$6708 absorption feature confirms the youth of t…

astro-ph.HEastro-ph.GA

25 Years of Mrk 421 with XMM-Newton: Unveiling Structured Jets and Energy-Dependent Escape

Tek P. Adhikari, Gopal Bhatta, Sangeetha Kizhakkekalam, Navaneeth P K, Alex Markowitz, Zhicheng He, Santanu Mondal

We present a long-term X-ray spectral and timing analysis of the TeV blazar Mrk~421 based on nearly a quarter century of archival \textit{XMM-Newton}/pn observations obtained between 2000 and 2025. Our sample comprises 76 epochs obtained with the pn instrument in both IMAGING and TIMING modes, allowing us to trace the source's variability and spectral evolution. Mrk~421 exhibits flux variations by approximately an order of magnitude, with prominent flaring periods interspersed with low-activity…

astro-ph.GAastro-ph.HEastro-ph.SR

Chemical complexity in feedback from supernova remnants: first detection of PO+ in IC443 and W44

G. Cosentino, F. Priestley, S. Scibelli, F. Fontani

Supernova remnant (SNR) may shape the physical and chemical properties of star formation. By releasing refractory elements into the gas phase, they inject material of pre-biotic relevance into molecular clouds. Such elements may be inherited by planetary systems and become relevant for the emergence of life. We investigate the presence of P-bearing species in molecular clouds impacted by SNR-shocks. P is a crucial biological element, but its presence and reservoir in molecular clouds remain elus…

astro-ph.GAastro-ph.CO

Do Submillimeter Galaxies Trace Megaparsec Large-scale Structures? -- An Overdensity Analysis of 449 Submillimeter Galaxies in COSMOS

Canze Deng, Daizhong Liu, Helmut Dannerbauer, Gianluca Castignani, Rosa Calvi, Lauro Moscardini, Benjamin Magnelli, Sylvia Adscheid et al.

We present an environmental analysis and overdensity catalog for a large sample of submillimeter galaxies (SMGs) in the COSMOS field in order to understand whether SMGs are signposts of megaparsec-scale overdensity structures. We apply the Poisson Probability Method (PPM) protocluster finder to characterize the significance ($σ$) and overdensity value ($δ$) of any overdense structures surrounding specific 'beacon' galaxies. These beacons include 449 SMGs from A3COSMOS (including 168 with spectro…

astro-ph.HE

Superorbital Phase Evolution and Identification of New Anomalous Low State Candidates for Her X-1

Yi Chou, Jun-Lei Wu

The 35-day superorbital modulation of the X-ray binary Her X-1 was systematically investigated using a 35-year multi-instrument X-ray observational baseline. We developed a Rank-Searching method using the peak intensity of the main high state to identify anomalous low states (ALSs) with an objective and reproducible criterion. The method recovers the known ALSs, identifies two previously unrecognized candidate episodes, ALS 1991 and ALS 2015, and independently recovers the recently reported ALS…

astro-ph.HE

Eight Gamma-Ray Bursts Observed with the Fermi Gamma-ray Burst Monitor: Significant Quasi-Thermal Components and Conditional Jet Constraints

Ze-lian Du, Zhao-Yang Peng, Jia-Ming Chen, Yue Yin, Ting Li

The composition of gamma-ray burst (GRB) jets remains uncertain. We analyze eight Fermi Gamma-ray Burst Monitor (GBM) GRBs with reported redshift information, selected from 126 events by prespecified fluence and spectral criteria. After excluding compound-model DIC evaluations classified as unstable by the posterior-stability tests, a stable added-blackbody (BB) comparison gives $Δ\mathrm{DIC}>10$ in 203 of 215 accepted bins (60--100\% per burst); independently, a multicolor-blackbody plus power…

astro-ph.EP

Planetary eccentricity enhances inward comet transport but suppresses gentle impacts

Qunfeng Jiang

Comets can supply volatile and prebiotic material to rocky planets, but survival of fragile molecules depends on atmospheric entry and impact. Compact planet chains can transfer comets inward at low velocity. We test whether modest planetary eccentricity preserves this route. We follow 64,000 comets from the region between the two outermost planets of an eight-planet chain to an Earth-mass planet on a temperate orbit around a $0.1 M_\odot$ star. A second suite of simulations isolates the last tr…

astro-ph.IMastro-ph.EP

Comparing Optimized Systematic Error Correction Methods on Selected TESS Light Curves

David Rapetti, Jon Jenkins, Joseph Twicken, Douglas Caldwell, Jeffrey Smith

The correction of systematic errors in TESS light curves is crucial for all astrophysical analyses employing these observations. Here we present a data analysis and a software package, SysCoCoPy, to investigate and directly compare the performance of the Presearch Data Conditioning (PDC) correcting method from the Science Processing Operations Center (SPOC) pipeline and three correctors developed by the community. We incorporate these three correctors based on their implementations in Lightkurve…

astro-ph.SRastro-ph.HE

1RXS J174320.1-042953: another polar with a red-shifted absorption component in emission line wings

Diego H. González-Buitrago, Ma. T. García-Díaz, Sergey Zharikov, Gagik Tovmassian, A. Castro, E. J. Kotze, Yair Krongold, C. A. Negrete et al.

We present the results of a spectroscopic and multi-band photometric study of the magnetic cataclysmic variable 1RXS J174320.1-042953. Multi-band photometry confirms a periodic modulation with an orbital period of $P_{\rm orb}=0.0864 \pm 0.0001$ days. Using the estimated secondary mass of $\sim0.15\,\mathrm{M_\odot}$ and, the X-ray-based white dwarf mass of $\sim0.75\,\mathrm{M_\odot}$, we obtain values of $q\sim0.2$ and a system inclination of $47^\circ\pm10^\circ$. The optical spectra of 1RXS…