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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.HE

When will T Coronae Borealis next erupt as a nova? Constraints from recurrence, orbital phase, and accretion-state evolution

Songpeng Pei, Xiaowan Zhang, Renzhi Su, Ziwei Ou, Yongzhi Cai, Qiang Li, Yu Liu, Xiaoqin Ren et al.

T Coronae Borealis (T CrB) is the nearest symbiotic recurrent nova and is now intensively monitored for its next eruption. We combine three constraints on the eruption time: historical recurrence, orbital phase, and recent accretion-state evolution. Conditioning on no eruption by 2026 July 11, the three effective historical intervals give illustrative survival-conditioned probabilities of 30.2\% for the rest of 2026 and 56.9\% within the following year; these are empirical indicators, not physic…

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astro-ph.EPphysics.geo-ph

Sulfur photochemistry observationally traces mantle redox states of rocky planets

Ioannis Panagiotou, Tim Lichtenberg, Shang-Min Tsai, Harrison Nicholls

Volatile outgassing from planetary interiors controls the composition of rocky exoplanets' secondary atmospheres. However, observations indicate that disequilibrium processes, such as photochemistry and vertical transport, can strongly alter the chemical structure of Hot Jupiters. Which process dominates under different types of rocky planets, and how outgassing and photochemistry jointly determine the atmospheric composition, remain open questions. Sulfur species are promising tracers of interi…

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astro-ph.HE

Spectral study of the outburst decay of the accreting millisecond X-ray pulsar SRGA J144459.2-604207

Amar Deo Chandra

We study the spectra of the accreting X-ray millisecond pulsar SRGA J144459.2-604207 during the 2024 outburst using the Neutron star Interior Composition Explorer (NICER) and Swift observations. The spectra during the outburst decay, reflares, and quiescent state are explored using the absorbed Comptonized model. We find that the spectra during the quiescent state can also be explained using the absorbed power-law and absorbed blackbody model. The spectral evolution of the source is explored as…

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astro-ph.GAastro-ph.SR

Cluster characteristics of Galactic open clusters

K. Neumannová, J. Supíková, N. Faltová, P. Mondal, E. Paunzen, T. Ramezani, G. Szász

Star clusters are perfectly suited for studying the formation, evolution, and dynamics of stars and their host galaxies. For this, we need to estimate total masses, radii and shapes of star clusters. These parameters strongly influence their fates in the host galaxies. However, there is no agreement about these characteristics in the literature. The published values widely disagree. We estimated total masses and cluster radii using a very conservative approach: calculating member masses and summ…

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astro-ph.EP

The majority of hot Jupiters formed beyond the water ice line

Yaxing He, Bertram Bitsch, Adrien Houge, Joe Williams, Masahiro Ogihara

Atmospheric compositions of giant exoplanets can retain information about their formation environments, as volatile species condense at different temperatures in protoplanetary discs. We investigated whether the atmospheric compositions of hot Jupiters can constrain their formation locations. We performed planet formation simulations using the ChemComp code, including pebble drift, pebble and gas accretion, planet migration, stellar abundances, and two additional chemical processes: thermal deco…

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astro-ph.GA

Berkeley 32: A Metal-poor and Dynamically Evolved Open Cluster with Evidence of Radial Migration

Deniz Cennet Çınar, D. Bisht, Ing-Guey Jiang, W. H. Elsanhoury, K. Belwal, Selçuk Bilir

We present a comprehensive chemo-dynamical analysis of the old, metal-poor open cluster Berkeley 32 based on Gaia DR3 astrometry and Gaia-ESO Survey DR5.1 spectroscopy. Cluster membership is determined using a Gaussian Mixture Model applied to proper-motion components and trigonometric parallaxes. Isochrone fitting yields an age of 4.9 +/- 0.5 Gyr, a heliocentric distance of 3325 pc, and an extinction of A_V = 0.38 +/- 0.12 mag. Spectroscopic member stars exhibit a mean metallicity of [Fe/H] = -…

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astro-ph.HEastro-ph.IMgr-qc

Swift gives a new BAT-GLIMPSE: Gamma-ray Localization using Imaging and Mosaic techniques for Pointing and Slew Epochs

S. Ronchini, T. Parsotan, J. DeLaunay, J. A. Kennea

The Burst Alert Telescope (BAT) onboard the Neil Gehrels Swift Observatory is capable of localizing gamma-ray transients with arcminute precision, enabling rapid multi-wavelength follow-up. However, onboard triggering is disabled during spacecraft slews, preventing the autonomous detection and localization of transients occurring during these intervals. We present here BAT-GLIMPSE, a fully autonomous, open-source pipeline for the low-latency localization of transient gamma-ray sources in Swift-B…

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astro-ph.IM

Low-Frequency VLBI Network Using SKA-LOW

Hideyuki Kobayashi, Tomoaki Oyama, Kazuma Fujita, Syunsaku Suzuki, Shintaro Yoshiura, Hiroaki Misawa, Fuminori Tsuchiya, Kazuhiro Takefuji et al.

We propose the development of a low-frequency Very Long Baseline Interferometry (VLBI) network operating in the 100-350 MHz range, incorporating the Square Kilometre Array Low (SKA-LOW). SKA-LOW is expected to achieve exceptionally high sensitivity within this frequency band. By integrating SKA-LOW with other high-sensitivity radio telescopes located across the Asia-Pacific region, the proposed network is anticipated to deliver up to two orders of magnitude improvement in sensitivity compared to…

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astro-ph.HE

PeV extended emission around Galactic PeVatrons and echos of their flares

A. Neronov, Ie. Vovk

We notice that Galactic sources of PeV gamma-rays are generally expected to be surrounded by multi-degree-scale extended emission produced as a result of injection of electron-positron pairs in the interstellar medium from interactions of PeV gamma-rays with microwave photons. The surface brightness of such emission may be variable in time because of variability of the PeV emission power of its parent source. A flare of the parent source produces an ``echo'' spreading across the extended emissio…

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astro-ph.SRastro-ph.GA

The non-LTE abundances of magnesium and yttrium and asteroseismic ages for the chemical clock calibration

Š. Mikolaitis, G. Tautvaišienė, E. Pakštienė, A. Drazdauskas, V. Bagdonas, C. Viscasillas Vázquez, M. Ambrosch, Y. Chorniy et al.

Building on our previous study, which demonstrated the importance of accounting for departures from local thermodynamic equilibrium (LTE) in elemental-abundance determinations and of using asteroseismic ages, we investigate spatial variations in the empirical [Y/Mg]-age relation across the Galactic disc using a substantially larger stellar sample. We analysed high-resolution stellar spectra and determined Mg and Y abundances through spectral synthesis of multiple spectral features, rigorously ac…

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astro-ph.EPphysics.ao-phphysics.geo-ph

Atmospheric evolution through outgassing and escape on young molten rocky exoplanets

Emma Postolec, Tim Lichtenberg, Harrison Nicholls, Laurent Soucasse, Floris van der Tak

The earliest rocky planet atmospheres are shaped by competition between initial volatile inventories and atmospheric escape. On young magma ocean planets, outgassing competes with atmospheric escape, controlling volatile retention and atmospheric evolution. We investigate how atmospheric escape and replenishment via outgassing during magma ocean crystallization shape rocky planet atmospheres. We extend a coupled interior-atmosphere model to simulate rocky planet evolution during the magma ocean…

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astro-ph.GA

The World Cup in space: Finding ionised buckyballs in the ISM with CARMENES

J. Maíz Apellániz

Over a century after the discovery of the first diffuse interstellar bands (DIBs) in absorption in stellar spectra (Heger et al 1922), their origin is still mostly unknown. The exception are four DIBs (out of 600+ known) in the 9300-9700 Angstrom region, for which a possible ascription to C_60^+ (ionised buckminsterfullerene, shaped liked a football, hence buckyballs) has been made. However, those DIBs are located in a spectral region heavily contaminated by telluric H_2O absorption, hampering t…

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astro-ph.SRastro-ph.GA

Stellar Multiplicity in Open Clusters: Investigating Binary Fractions and Their Relationship with Cluster Properties

Ruan P. Alves, Hektor Monteiro, Wilton S. Dias, Gabriel R. Hickel

Stellar multiplicity is key in dynamical evolution of open clusters (OCs) and processes of stellar formation and evolution. Since most stars form in multiple systems, investigating how environmental properties affect their occurrence is crucial. We aim to investigate how binary fraction and mass ratios change across different OC environments. Using a sample of 773 OCs, we identified binary systems and estimated binary fractions, obtaining values in the ranges 0.10-0.85 overall and 0.06-0.79 for…

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astro-ph.GAphysics.chem-ph

Isomer-specific excitation of formic acid in collisions with helium atoms

Karina Sogomonyan, Anzhela Veselinova-Marinova, François Lique, Jérôme Loreau

An accurate estimation of the molecular abundances of isomers in the interstellar medium (ISM) is necessary to unravel the underlying chemistry and physics. After the recent detections of both isomers of formic acid ($cis-$ and $trans-$HCOOH) in dense dark cold clouds, their accurate molecular line modeling became of interest. The conditions of these environments do not necessarily follow the local thermodynamic equilibrium, thus taking into account the competition between the radiative and coll…

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astro-ph.HEastro-ph.CO

Testing the Isotropy of the Universe with the CHIME/FRB Catalog I

Jun-Yi Shen, Yuan-Chuan Zou

We test the isotropy of the Universe using 536 Fast Radio Bursts (FRBs) from the first CHIME/FRB catalog, employing two complementary statistical methods: the two-point angular correlation function (2PACF) and the sigma-map method, with observational biases corrected using CHIME injection data. Both analyses are consistent with the isotropic expectation, but are limited by the small sample size. The 2PACF suffers from an ill-conditioned covariance matrix, preventing robust parameter inference. T…

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astro-ph.HEhep-phhep-thnucl-th

A self-consistent Higgs-portal framework for dark matter--admixed neutron stars: Collider-motivated benchmarks meet multimessenger constraints

Adamu Issifu

We investigate dark matter (DM)-admixed neutron stars (NSs) within a self-consistent single-fluid relativistic mean-field framework by extending the Higgs-portal model with a massive $Z^\prime$ vector mediator. The resulting density-dependent repulsive interaction dynamically couples the baryonic matter (BM) and DM sectors, allowing the DM content to be characterized by the global particle fraction, $F_χ=N_χ/N_B$, with the local DM density determined self-consistently as $n_χ=F_χn_B$, thereby el…

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astro-ph.GA

The Goldilocks Molecule: H$_{2}$ Emission Lines Can Identify Elusive Dwarf AGN

Morgan Micharski, Chris Richardson

We propose using H$_{2}$ emission lines as a novel diagnostic to identify dwarf AGN by running photoionization models incorporating active intermediate-mass black holes and using an observed WISE dwarf AGN as a template. Though many dwarf AGN would be incorrectly classified as star-forming if the H$_{2}$~2.12~$μ$m/Br$γ$ ratio is used, ratios between H$_{2}$ emission lines can reveal active IMBHs in cases where log $n_{\text{H}} \gtrsim 4.0$. This includes the case where $M_{\text{BH}} = 10^3~M_{…

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physics.hist-phastro-ph.HEastro-ph.IMgr-qc

Coloring Black Holes: Epistemic and Aesthetic Choices in Astronomical Imaging

Rodrigo Ochigame, Emilie Skulberg, Jeroen van Dongen

In 2019, the first image of a black hole's shadow based on observation was released by the Event Horizon Telescope Collaboration (EHT). This paper shows that despite the EHT's emphasis on a single image as its final result, there were countless plausible ways of rendering the data, among which researchers could not easily choose. To obtain a single image from the extremely noisy and sparse data, it was necessary to select one of multiple plausible approaches, or to average the results from diffe…

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astro-ph.IM

DD4AO control law for RISTRETTO: robustness, real-time performance, and on-sky validation with PAPYRUS

Isaac Dinis, Muskan Schinde, Nicolas Blind, Bruno Chazelas, Nathanael Restori, Christophe Lovis, Sylvain Cetre, Angelie Alagao et al.

This study presents DD4AO progress towards its implementation in the RISTRETTO instrument. DD4AO is a novel frequency-domain, data-driven controller for adaptive optics that leverages power spectral density estimation for optimization while enforcing stability criteria. It addresses disturbance rejection, command amplitude constraints, and system transfer functions through convex optimization, yielding an optimal controller in Infinite Impulse Response (IIR) filter form. We present the on-sky va…

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astro-ph.GA

The COLIBRE-SKIRT pipeline: Calibration-free dust radiative transfer postprocessing for cosmological simulations

Andrea Gebek, Maarten Baes, Nick Andreadis, Joop Schaye, Anand Utsav Kapoor, Connor Bottrell, Shengdong Lu, Cedric G. Lacey et al.

Context. Three-dimensional dust radiative transfer provides a powerful framework to connect cosmological galaxy simulations to multiwavelength observations. Until recently, in large-volume simulations, the formation of a cold ISM phase was prevented and dust was not evolved self-consistently. This required calibration of dust-to-metal ratios and extra subgrid dust attenuation in birth clouds, thereby reducing the predictive power. Aims. We present the COLIBRE-SKIRT pipeline, a calibration-free d…

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astro-ph.EPastro-ph.GAastro-ph.SR

Dust masses of Upper Scorpius disks and their statistics

Huiyi Deng, Yao Liu, Min Fang

The total dust mass of protoplanetary disks is a key property that determines the potential for planet formation. Upper Scorpius (USco), with an age of ~5-12Myr, provides an important laboratory for investigating the evolution of dust reservoirs on timescales comparable to those of planet formation. In this work, we analyze the dust mass distribution of 136 full and transitional disks in USco using the largest ALMA 0.88mm continuum sample currently available for the region. To improve the accura…

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astro-ph.EP

Flow-Driven Limb-Asymmetry of Haze Distribution Part I: An Analytical Framework for Predicting the Size Distribution of Photochemical Hazes Across the Two Limbs of hot-Jupiters

Mei Ting Mak, Thaddeus D. Komacek, Nathan J. Mayne, David K. Sing

Photochemical haze, a common aerosol type expected to form in the atmospheres of hot-Jupiters, can become concentrated to different extents between the morning and evening limbs depending on the balance between advection, gravitational settling, and radiation pressure. We present a analytical framework incorporating the effect of gravity, planetary radius, and stellar flux, alongside the particle size of the haze on its resulting relative distribution between the two limbs. Using this framework…

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astro-ph.GA

Discrepancies between Chandrasekhar's theory of relaxation and $N$-body simulations

Kerwann Tep, Douglas C. Heggie

Globular clusters are systems which are known to be particularly well described by two-body relaxation. In recent decades many studies have shown that Chandrasekhar's orbit-averaged theory is able to reproduce many features of numerical simulations. However, it has been claimed that differences between the theory and simulation remain, such as an amplitude mismatch of the rate of change of the distribution function. In this paper we compare the theoretical predictions of Chandrasekhar's theory f…

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astro-ph.IMphysics.optics

Millimetre-scale spectrographs for next-generation photonic instrumentation

Emily Ronson, Robert J. Harris, Ariadna Calcines Rosario, Viktoria Kutnohorsky

We present a set of ultra-compact spectrographs fabricated using two-photon polymerisation, each under 1 mm in length and printed directly onto an optical fiber. This fully integrated, alignment-free architecture enables extremely low-mass instrumentation with broad potential across astrophotonics, space systems, drone-based sensing, and quantum optics. Two transmissive configurations are presented; they combine beam-expansion optics, dispersive elements, and stray-light suppression within monol…

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astro-ph.HEgr-qc

SPH methods in the modelling of compact objects

Stephan Rosswog

We review the current status of compact object simulations that are based on the Smoothed Particle Hydrodynamics (SPH) method. The first section of this review is dedicated to SPH as a numerical method for Newtonian, ideal gas dynamics and it should be fairly self-contained. It begins with the basics of the method, but also describes recent advances including various meshless derivatives or methods for treating shocks. A separate chapter summarizes general relativistic SPH, including its special…

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astro-ph.GA

Fuelling the central region of galaxies with misaligned gas accretion

J. L. Tous, S. I. Raimundo, R. Riffel, A. Puglisi, F. Shankar, M. Vestergaard

Recent studies have shown that the accretion of kinematically misaligned gas fuels the central reservoir of galaxies, triggering nuclear activity and star formation. In this work, we show that this specific accretion channel can only sustain main-sequence levels of star formation in galaxies with $M_* \lesssim 10^{10} {\rm M_\odot}$. Using a sample of 201 kinematically misaligned galaxies, and a comparison sample of 3689 aligned galaxies, from the Mapping Nearby Galaxies at Apache Point Observat…

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astro-ph.IMphysics.ed-ph

MIRA: a data management and education platform connecting students to robotic telescopes

Peter P. Pedersen, Lionel Garcia, Mahshid Alimi, David Degen, Florian Lienhard, Didier Queloz

Hands-on telescope experience is often used to drive student engagement in astronomy education, but scaling access to larger groups of students is operationally challenging. Consequently, students encounter only a fraction of the professional workflow, rarely engaging with the rigorous peer-review, time-allocation processes, or automated data reduction pipelines that govern modern research facilities. We present the design of MIRA (Mentored Investigations using Robotic Astronomy), a data managem…

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astro-ph.SR

Search for double-line spectroscopic binaries in RAVE survey

Mikhail Kovalev

I present a study for double-line spectroscopic binaries content in spectra from the RAVE spectra, using composite spectral model. Three complementing selections found 2813 composite spectra, belonging to 2605 unique targets. Also these results were compared with automatic classification based on t-SNE map, which shows good agreement. Additionally I identified several spectra affected by problems with wavelength calibration.

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astro-ph.COastro-ph.HEgr-qc

Probing Graviton Mass with MeerKAT PTA and SKA--PTA Forecasts

Zhi-Chao Zhao, Sai Wang

We present constraints on the graviton mass using the 4.5-year data release from the MeerKAT Pulsar Timing Array (MPTA) and provide forecasts for the upcoming Square Kilometre Array PTA (SKA--PTA). By modeling the modified dispersion relation and the corresponding tensor correlation function for massive gravitons, we perform Bayesian inference on the angular-correlation measurements under three noise configurations (DATA, ER, ALT). Our 90\% credible upper limits on the graviton mass are $m_g < 2…

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astro-ph.EPastro-ph.SR

Dust Growth in Binary Systems: Inhibition of dust settling and growth in circumbinary discs

Antoine Alaguero, Nicolás Cuello, Jean-François Gonzalez, Daniel J. Price, Maxime Lombart, Jeremy L. Smallwood, Philippe Thébault

Stellar multiplicity alters the density structure of protoplanetary discs and thereby the initial conditions for planet formation. Yet, the interplay between companion-disc interactions and dust growth remains poorly understood. The goal of this work is to investigate to what extent the density structure of a disc undergoing tidal interactions with a companion star promotes or inhibits the growth of dust grains. We perform a set of hydrodynamical simulations of protoplanetary discs orbiting one…

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