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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.SRastro-ph.EP

The Effects of Magnetic Accretion on the Spatial Extent of White Dwarf Pollution

Dang Pham, Aster G. Taylor, Tim Cunningham

Many white dwarfs are polluted by metals, which are generally understood to be the accreted remnants of a planetary system. Modeling these systems typically assumes that the metal concentration is homogeneous throughout the white dwarf's atmosphere. However, the magnetic fields of a white dwarf may affect the accretion geometry of the white dwarf via magnetospheric accretion. Convection in the white dwarf's photosphere will then transport the metals across the surface, with a structure set by th…

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astro-ph.SR

An extensive grid of DARWIN models for M-type AGB stars II. Effects of pulsation periods on wind properties

Emelie Siderud, Kjell Eriksson, Susanne Höfner, Arief Ahmad

Mass loss from asymptotic giant branch (AGB) stars is the result of a complex interplay between pulsation, atmospheric dynamics, dust formation, and radiative acceleration. Pulsation periods are a key input in dynamical atmosphere and wind models, and different prescriptions for assigning periods based on stellar parameters may lead to systematic differences in the predicted wind properties. To better constrain this critical parameter, we investigated how the choice of pulsation period affects t…

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astro-ph.GA

Hierarchical Bayesian inference with compositional score modeling for stellar streams

Giuseppe Viterbo, Jonas Arruda, Tobias Buck

Context: Stellar streams trace the gravitational potential of the Milky Way over a wide range of Galactocentric radii. Since different streams sample different regions of the Galaxy, combining several of them can constrain the global mass distribution more tightly than modeling any single stream in isolation. Most of the existing multi-stream analyses rely on likelihood-based methods that require a new inference run whenever additional streams or kinematic measurements become available. Aims: We…

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astro-ph.IM

RAMSES-GPU: Cell-by-Cell Adaptive Mesh Refinement with Magneto-Hydrodynamics and Self-Gravity on Graphics Processing Units

Romain Teyssier, Eric Moseley, Robert V. Caddy, Troels Haugbolle, James Sunseri, Jun-Young Lee, Jonathan Palafoutas, Yue Pan et al.

We present the implementation and optimization of the cosmological simulation code RAMSES on Graphics Processing Units (GPUs) using CUDA Fortran. This accelerated version ports the main computational routines, including hydrodynamics, particle dynamics, and self-gravity, to multi-GPU architectures. We detail our strategy for managing cell-by-cell Adaptive Mesh Refinement (AMR) on the GPU, utilizing bucket sort with prefix sums for AMR level sorting, radix sort via the CUB library for Hilbert key…

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astro-ph.HEnucl-th

Reaction-constrained composition \(g\)-modes in neutron stars with antikaon condensates, hyperons, and \(Δ(1232)\) resonances

Prashant Thakur, Ishfaq Ahmad Rather

We study core composition \(g_1\) modes of cold, nonrotating neutron stars containing antikaon condensates, hyperons, and \(Δ(1232)\) baryons and present, to our knowledge, the first calculation in full general relativity of the continuous-composition \(g_1\)-mode frequency and gravitational-wave damping time for stars with a \(K^-\) condensate. Using the BigApple relativistic mean-field equation of state, we compute frequencies, damping times, and frozen-composition tidal overlaps, and identify…

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astro-ph.SRastro-ph.EPastro-ph.GA

Statistics on the population of distant substellar companions to nearby stars

Souleymane Ouedraogo, Étienne Artigau, Sié Zacharie Kam, Orlagh L. Creevey, Clémence Fontanive, Neil J. Cook, René Doyon, Fabrice Bado et al.

Context. Wide substellar companions provide important benchmarks for studying the formation and evolution of brown dwarfs and giant planets. Their association with stellar primaries also provides age and metallicity constraints that are difficult to obtain for isolated objects. Aims. We investigate the population of wide substellar companions to nearby main-sequence stars using proper motions derived from multi-epoch WISE imaging. Our sample includes 2103 stars within 20 pc and is sensitive to c…

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astro-ph.IMastro-ph.GAastro-ph.HE

A multi-band radio flux density catalog of ICRF3 sources using the Onsala Twin Telescopes

Alva Kinman, Rüdiger Haas, Karine Le Bail, Jun Yang, Eskil Varenius

The VLBI Global Observing System (VGOS) is the next generation system for geodetic and astrometric Very Long Baseline Interferometry (VLBI). To optimize the observing time for each source in geodetic schedules, a flux density catalog is needed for the sources that are observed at the VGOS frequencies. The aim of this work is to monitor the flux densities of geodetic sources in the VGOS bands. The obtained flux density time series can be used for more effective scheduling of geodetic and astromet…

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gr-qcastro-ph.HEastro-ph.IM

A product template bank to search for compact binary coalescences microlensed by isolated point mass lenses

Sudhir Gholap, Sanjeev V. Dhurandhar, Shasvath J. Kapadia

Gravitational waves (GW) from stellar mass compact binary coalescences (CBCs) that encounter a lens whose Schwarzschild radius is comparable to the GW wavelength, will be microlensed, leading to frequency-dependent modulations in the observed signal. Neglecting such wave-optics effects in standard templated searches for CBCs can result in signal-to-noise ratio (SNR) losses as large as 30%. Here, we present a prescription for constructing a template bank targeted at microlensed GWs. We consider C…

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astro-ph.COastro-ph.GA

When galaxies burst II. Implications of enhanced burstiness for the 21-cm Cosmic Dawn signal

Hovav Lazare, Sarah Libanore, Eleonora Vanzan, Julian B. Muñoz, Ely D. Kovetz

Recent JWST observations suggest that star formation in the early universe was substantially burstier than assumed in standard models. Such burstiness can be described as a stochastic process characterized by the burst amplitude and the coherence time of star formation epochs. In this paper, we investigate how bursty star formation modifies the 21-cm power spectrum during Cosmic Dawn through its impact on the non-local radiation fields that govern its evolution, namely Lyman-$α$ and X-ray backgr…

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astro-ph.SRastro-ph.EP

A Quiet Host in an Active Planet-Forming Disk: Optical Spectroscopy of WISPIT

C. Swastik, M. Bestha, L. S. Sonith, S. Facchini, T. Sivarani, R. K. Banyal, Z. Wahhaj, A. Choudhary et al.

WISPIT 2 is a young pre-main-sequence star hosting a multi-ringed transition disk and two directly imaged protoplanets, including the accreting WISPIT 2b, making it the closest known analogue to PDS 70. We present the first optical spectrum of its central star, obtained with HFOSC on the 2-m Himalayan Chandra Telescope, and derive its atmospheric parameters, test its youth, and constrain its accretion state. We analyse low-resolution spectra with iSpec and validate the pipeline at HFOSC resoluti…

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astro-ph.SRastro-ph.EP

A Quiet Host in an Active Planet-Forming Disk: Optical Spectroscopy of WISPIT 2

C. Swastik, M. Bestha, L. S. Sonith, S. Facchini, T. Sivarani, R. K. Banyal, Z. Wahhaj, A. Choudhary et al.

WISPIT 2 is a young pre-main-sequence star hosting a multi-ringed transition disk and two directly imaged protoplanets, including the accreting WISPIT 2b, making it the closest known analogue to PDS 70. We present the first optical spectrum of its central star, obtained with HFOSC on the 2-m Himalayan Chandra Telescope, and derive its atmospheric parameters, test its youth, and constrain its accretion state. We analyse low-resolution spectra with iSpec and validate the pipeline at HFOSC resoluti…

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astro-ph.EPastro-ph.SR

Evidence for a giant companion orbiting Tabby's star

Cristina Madurga-Favieres, P. A. Strøm, Thomas G. Wilson, Neda Heidari, Flavien Kiefer

KIC 8462852, also known as Tabby's star, shows deep, irregular flux variations up to 20 per cent in its Kepler light curve. These unusual events show no apparent periodicity. Multi-wavelength observations show the dips are consistent with transiting dust, although its origin remains uncertain. The leading explanation is that dust may originate from a family of exocomets or planetesimal fragments. TESS data reveal a unique, symmetric transit event consistent with a planet or brown dwarf. This wou…

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astro-ph.IMcs.DCphysics.comp-ph

STORM: RDMA-based Monte Carlo Transport Scheme for Distributed-Memory Particle Simulations

Maor Mizrachi, Barak Raveh, Elad Steinberg

Monte Carlo particle transport enables high-fidelity astrophysical radiation and neutrino simulations - from core-collapse supernovae and neutron-star mergers to accretion flows - by handling multidimensional geometries, frequency dependence, and moving media without angular discretization. However, inter-rank communication limits scalability on unstructured meshes: standard two-sided MPI requires receivers to post receives and poll completions, creating per-iteration progress overhead that grow…

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astro-ph.GA

A Naked Dwarf: Molecular Gas in the Completely Stripped HI Tail of VCC 1249

Bumhyun Lee, Aeree Chung, Paolo Serra, Nikki Zabel, Sungsoon Lim, Hyein Yoon, A. Boselli, Matteo Fossati et al.

We present the first observational hints of the severe removal of both molecular and HI gas from the dwarf galaxy VCC 1249. This extreme stripping event is thought to be driven by the combined effects of tidal interaction and ram pressure. Using deep CO (2$-$1) observations from the James Clerk Maxwell Telescope (JCMT), we obtained marginal CO detections in three regions within the stripped HI tail, with molecular masses of $\sim$10$^{5}$ to 10$^{6}$$M_{\odot}$, comparable to typical masses of g…

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astro-ph.HEastro-ph.GA

Time-evolving Diagnostic of the Ionized Absorbers in NGC 4051. II. High-throughput Time-resolved Spectroscopy

Alfredo Luminari, Fabrizio Nicastro, Roberto Serafinelli, Riccardo Middei, Yair Krongold, Elias Kammoun, Luigi Piro, Francesca Diaferia et al.

Active Galactic Nuclei (AGNs) are one of the most powerful sources in the Universe. The accretion-liberated energy can strongly impact the surrounding environment, up to the host galaxy and beyond. Notwithstanding their ubiquitous presence, nuclear outflows are poorly characterised, mainly due to the degeneracy between their number density $n_e$ and radial location $r$, intrinsic in the photoionisation equilibrium models which are usually employed to fit the observations. This degeneracy prevent…

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hep-phastro-ph.HEhep-ex

Dark Matter Weather: Probing Sub-GeV Interactions with Earth-Shielding Modulation

Tetiana Kozynets, Rebecca Leane, Juri Smirnov

Daily modulation from Earth shielding provides a powerful search handle for sub-GeV dark matter (DM) in low-threshold experiments. We use this effect as a probe of interaction structure in scenarios where DM couples to both electrons and nuclei. Nuclear scattering in the Earth alters the incident DM flux, while electron scattering produces the observable ionization signal, so the total rate and modulation pattern encode different aspects of the underlying interactions. We develop this two-intera…

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astro-ph.HE

Polarization of impulsive relativistic jets propagating in a stratified medium

Gal Birenbaum, Paz Beniamini, Jonathan Granot

Gamma-ray bursts (GRBs) and at least some tidal disruption events (TDEs) are highly energetic transients involving impulsive relativistic jets. As these jets propagate into their surrounding media, they drive a relativistic forward shock into it, which radiates multi-wavelength polarized synchrotron emission, known as an afterglow. Analyzing the afterglow light curve along with its polarization curve can shed light on the geometrical properties of the GRB or TDE system such as the magnetic field…

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

A dust-free hierarchically nested supermassive-star model for James Webb Space Telescope Little Red Dots

Pau Amaro Seoane

Observations by the James Webb Space Telescope reveal a population of high-redshift objects, the little red dots. These sources exhibit optical reddening alongside blue ultraviolet continua, host broad Balmer lines indicative of active black holes, and lack detectable x-ray emission. Their cosmic abundance at early epochs exceeds standard Eddington-limited growth timescales. Prevailing models invoke specific dust geometries to reconcile these traits. We propose a dust-free physical framework. We…

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astro-ph.GAastro-ph.SR

Two stellar clocks, one history: a Gaia colour-magnitude-diagram reconstruction of the solar-neighbourhood star-formation history tested against white dwarfs

Michele Cignoni, Pier Giorgio Prada Moroni, Martina Gabbanini, Scilla Degl'Innocenti, Antonio Tinarelli

The solar-neighbourhood star-formation history (SFH) can be constrained from the colour-magnitude diagram (CMD) of non-degenerate stars and tested independently with the white-dwarf luminosity function (WDLF). These two tracers sample complementary evolutionary phases and provide a consistency check on both the recovered SFH and the adopted WD cooling models. We reconstruct the local SFH from the Gaia DR3 CMD and test whether the resulting history reproduces the observed 40 pc WDLF. We fit non-d…

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astro-ph.SRastro-ph.HE

A Framework for Linking Pre- and Post-Common Envelope Binary Properties with Star Clusters: The First Demonstration with a Massive White Dwarf+M Dwarf Binary in Alessi 12

Steffani M. Grondin, Maria R. Drout, Jason Nordhaus, Philip S. Muirhead, Bailey Filer, Alexander Laroche, Jeremy J. Webb, Floor S. Broekgaarden et al.

Common envelope (CE) evolution is a critical phase in the lives of binary stars, producing close binaries that are progenitors of type Ia supernovae and gravitational wave sources. Despite its importance, CE evolution remains poorly understood, largely due to the scarcity of systems with constrained pre- and post-CE properties. Here, we present a star cluster-based framework for reconstructing the evolutionary histories of white dwarf+main-sequence (WD+MS) post-CE binaries, where cluster members…

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astro-ph.HE

The Origin of the Magnetic Flux Driving TDE Jets

Nimrod Tripto, Julian Krolik, Tsvi Piran

Tidal Disruption Events (TDEs) occur when a star approaches a black hole closely enough to be torn apart by tidal forces, after which the stellar debris begins to orbit the black hole. Over the past decade, hundreds of TDEs have been identified, with many more expected from upcoming surveys. A small subset of these events launch transient, highly luminous relativistic jets (10^47-10^48 erg/s isotropic-equivalent). These are generally interpreted in terms of the Blandford--Znajek mechanism, imply…

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hep-phastro-ph.HE

Earth rotation turns event timing into a geometric probe of UHE neutrino origin

Andrew Cheek, João Paulo Pinheiro, Jordi Salvado

It has been proposed that the ultra-high-energy (UHE) event $\rm KM3-230213A$ detected by KM3NeT could be explained by dark matter (DM) decay. Prima facie this seems unlikely because the arrival direction of the event is opposite to the Galactic Centre. We develop a per-event test statistic to quantitively assess this possibility and forecast the required future events to exclude the DM hypothesis in favour of an isotropic signal. For the single event observed, the DM decay hypothesis is disfavo…

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astro-ph.HE

Revealing the Structure and Magnetization of GRB Jets with ALMA Polarization Observations

Tanmoy Laskar, Collin T. Christy, Noah Franz, Gavin Farley, Kate D. Alexander, Jonathan Granot, Ramandeep Gill, Tarraneh Eftekhari et al.

We present a systematic study of the currently available ALMA millimeter polarimetric sample of gamma-ray burst (GRB) afterglows. Our sample comprises 24 observations (20 new) of 11 long-duration GRBs spanning $\approx0.1$-87 days after the burst. We detect significant linear polarization in 8 observations across 6 events, with polarization degrees ranging from $Π_L\approx0.6\%$ to $2.4\%$. For the remaining observations, we place deep upper limits (median $Π_L\lesssim1\%$). Multi-epoch observat…

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astro-ph.GA

A New Model for the Milky Way Halo Dispersion Measure with the ENGAWA Simulations: Low DMs and Large Anisotropy

Scott Lucchini, Liam Connor, Samuel McCarty, Ralf M. Konietzka

Fast radio burst (FRB) dispersion measures (DMs) are powerful tracers of the low density universe, but interpretation is made difficult by the integrated nature of DM. In this paper, we analyze the new ENGAWA cosmological zoom-in simulation suite to constrain the DM contribution from the Milky Way (MW) halo. The ENGAWA simulations consist of four Milky Way-like galaxies with enhanced resolution in the circumgalactic medium, making them an excellent tool to probe the properties of the gaseous hal…

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gr-qcastro-ph.HE

Black hole-neutron star binaries with high spins and large mass asymmetries: III. Properties of the ejected material and its electromagnetic signatures

Konrad Topolski, Samuel D. Tootle, Paramvir Singh, Mattia Bulla, Luciano Rezzolla

Compact binary systems consisting of a black hole (BH) and a neutron star (NS) are expected to provide detectable signals both in the gravitational wave and in the electromagnetic channels, thus representing excellent sources for multi-messenger astronomy. In this third paper in a series, we report on the geometric and thermodynamic properties of the purely dynamical ejecta component modeled in our general-relativistic magnetohydrodynamical simulations of BHNS systems over a comprehensive binary…

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astro-ph.IM

Structural, thermal and optical tolerance analysis of SHARP, a near infrared spectrograph for next generation telescope

H. Mahmoodzadeh, P. Saracco, I. DI Antonio, P. Conconi, D. Scaccabarozzi, B. Saggin, E. Molinari, C. Arcidiacono et al.

The design and verification of cryogenic near-infrared spectrographs require rigorous multidisciplinary analyses to ensure optical performance under realistic operational conditions. In this work, we present a structural-thermal-optical performance (STOP) analysis of the SHARP instrument, a multi-mode spectrograph designed for use with upcoming multi-conjugate adaptive optics (MCAO) systems on Extremely Large Telescopes (ELTs). Transient and steady-state thermal simulations were performed using…

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astro-ph.GA

Outflows in the Early Universe: Neutral gas Absorption in Galaxies at z > 3 from low-resolution JWST Spectroscopy

Matteo Sapori, Sirio Belli, Letizia Bugiani, Amir H. Khoram, Caterina Liboni, Gabriel Maheson, Gabriel Brammer, Rebecca Davies et al.

Recent JWST/NIRSpec observations have shown that Na I D absorption tracing neutral gas outflows is widespread in massive galaxies at Cosmic Noon ($z\sim2$-$3$), but their prevalence at higher redshift remains largely unexplored. Here we investigate whether similar outflows are already in place during the first 2 Gyr of cosmic history ($z>3$), using a sample of 811 galaxies at $3 5$ in their JWST/NIRSpec PRISM low-resolution spectra ($R\sim100$). We derived physical properties and star formation…

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astro-ph.HEastro-ph.SR

Semi-analytical Light Curve Model for Transients Preceding Binary Mergers. I: Supernova Precursor Emission from Compact Object Companions

Daichi Tsuna, Morgan Macleod, V. Ashley Villar

A binary undergoing dynamically unstable mass transfer could rapidly shrink its orbit and lead to a merger, with the whole process often observable in human timescales. We construct a semi-analytical light curve model of binary systems composed of a star and a compact object accretor, that would display long-rising accretion-powered emission prior to a final merger-driven explosion. We apply the model to the precursors of interacting supernovae (SNe) that display long-rising light curves of year…

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astro-ph.GA

Estimating Cluster Galaxy Infall Time from Phase Space in TNG

Cameron Lawlor-Forsyth

Using the TNG300 and TNG-Cluster simulations, phase space-based estimates for galaxy infall time onto clusters with $M_{\mathrm{h}} \geqslant 10^{14}~M_{\odot}$ are determined for all simulation snapshots with $z \leqslant 1$. These infall time estimates are consistent with previous work in the literature, and can be readily applied to observations of cluster galaxies, where no other estimate is feasible, based only on the galaxy's position in projected phase space. The analysis pipeline used to…

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astro-ph.GAastro-ph.IM

Spectral Data-cube Cleaning for CCAT Deep Spectroscopic Survey. I. Effect of correlated noise and filtering on the power spectrum

A. Dev, C. Karoumpis, Y. Okada, K. Basu, F. Bertoldi, D. Chung, J. Clarke, R. Freundt et al.

The Epoch of Reionization Spectrometer (EoR-Spec) on the Fred Young Submillimeter Telescope (FYST) will conduct the CCAT Deep Spectroscopic Survey (DSS) to perform line-intensity mapping of redshifted [C II] emission. Atmospheric $1/f$ noise and instrumental systematics affect power-spectrum recovery. We present realistic end-to-end simulations to quantify these effects and evaluate a Filter-and-Bin (F&B) pipeline. The simulated observations include instrument response, astrophysical emission, a…

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