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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.SR

Bifrost spectral inversions, Fast non-LTE solar chromospheric diagnostics from 3D simulations

Elias R. Udnæs, Tiago M. D. Pereira, Ignasi J. Soler Poquet, Luc Rouppe van der Voort

Modern solar observatories produce vast amounts of detailed spectral data. To infer atmospheric parameters from these data, in particular for the solar chromosphere, requires immense computational resources. This problem is becoming more acute as spatial resolution improves, and faster methods are much needed to make sense of the data. Archive-based inversions provide a cost-effective way to infer atmospheric parameters from solar spectra, and involve building databases of synthetic spectra and…

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astro-ph.HE

Investigating the disappearance of a type-C QPO in black hole X-ray binary Swift J151857-572147 with AstroSat

Biki Ram, Manoneeta Chakraborty, Mayukh Pahari

We present a timing and broadband spectral study of the AstroSat observation of the black hole low mass X-ray binary Swift J151857.0--572147, focusing on its evolution across two temporal segments, S1 and S2. During the first segment S1 lasting $\sim$ 50.6 ks, the source shows a clear type-C QPO at $\sim8.02$ Hz and a low-frequency bump (LFB) in the power density spectrum. By the later segment S2, the strength of the QPO feature decreases significantly and is no longer consistent with a coherent…

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astro-ph.HEastro-ph.CO

FRB 121102: No supernova-like ejecta or magnetar power, hinting at a binary WD merger

Eli Waxman, Eran O. Ofek, Doron Kushnir

We use measurements of the time-dependent dispersion measure of the repeating FRB 121102, together with earlier radio observations of its associated persistent radio source (PRS), to derive stringent constraints on its underlying ``engine.'' The energy held by the relativistic PRS plasma is $>10^{49.5}$ erg, and its age is $\approx60$ yr, corresponding to an underlying source power exceeding $10^{40}$ erg s$^{-1}$. If the underlying source is a neutron star, this implies a rotational rather than…

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astro-ph.SR

Two Predicted, Concentric Nova Shells Surround the Prototype Dwarf Nova U Geminorum

Michael M. Shara, Kenneth M. Lanzetta, Aayushi Doshi, Alexandra Masegian, Stefan Gromoll, Yael Hillman, Susanne M. Hoffmann, David Valls-Gabaud et al.

In the 170 years since its discovery, U Gem has been intensively studied as the prototypical cataclysmic binary star. Its massive white dwarf (WD) (~ 1.2 Msun) is cannibalizing its ~ 0.42 Msun red dwarf companion. The WD's resulting accreted hydrogen-rich envelope has previously undergone thermonuclear runaways seen as nova eruptions. These weekslong transient events brighten U Gem to m ~ -3 and eject the accreted envelope (~ 0.00001 Msun) at thousands of km/s. Ultraviolet observations show that…

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astro-ph.IM

Background Intensity Estimation for Cassini-ISS Image Using Deep Learning-Based Diffusion Model

Yongxin Chen, Qingfeng Zhang, Tianle Zhou, Kai Tang

Accurate background intensity estimation is crucial for precise astrometric measurements in astronomical imaging, particularly in complex scenarios such as those encountered in Cassini Imaging Science Subsystem (ISS) observations of Saturn's ring system. Traditional methods, like polynomial fitting and statistical method, often fail in non-uniform conditions, such as those caused by Saturn's rings or scattered light, due to mismatched assumptions and reliance on prior knowledge. This results in…

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astro-ph.GA

Visualizing Disequilibrium: Tracing Two-Point Correlations to Specific Spatial Structures in the Milky Way

Austin Hinkel, Josephine Vanzant

The Two-Point Correlation Function can be used to demonstrate the existence of substructure within a dataset, but typical implementations do not track the individual points which contribute to each specific substructure. In this paper, we develop an algorithm that traces a two-point correlation signal back to the contributions of each data point, allowing for structure to be visualized in novel ways. Using this tool, we find substantial evidence for pervasive spatial clustering in the Milky Way…

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astro-ph.GA

A radio continuum view of Stephan's Quintet: age, dynamics and origin of the shock

K. Rajpurohit, E. O'Sullivan, G. Schellenberger, A. Botteon, R. J. van Weeren, U. Lisenfeld, J. M. Vrtilek, L. P. David et al.

We present a detailed, multi-band radio continuum study of the compact galaxy group Stephan's Quintet (HCG 92). We use a combination of new (MeerKAT, uGMRT) and archival (LOFAR, VLA) observations covering the $\rm 120\,MHz{-}8\,GHz$ frequency range to examine the radio properties of the group, focusing on the famous radio ridge and surrounding diffuse emission. We find filamentary substructure and branching in the southern half of the ridge, confirm an extension of the ridge to the northwest, an…

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astro-ph.GA

Systematic uncertainties on DESI Tully-Fisher distances constrained with Integral Field Spectroscopy

Utsav Siwakoti, Lluis Galbany, Kelly A. Douglass, Ariel J. Amsellem, Benjamin A. Weaver, J. N. Aguilar, S. Ahlen, D. Bianchi et al.

The Tully--Fisher (TF) relation is an empirical tool for estimating distances to spiral galaxies. The Dark Energy Spectroscopic Instrument (DESI) Peculiar Velocity (PV) Survey uses \texttt{`tractor'} photometric position angles to place fibers along the galaxy's semi-major axis and infer maximum rotational velocities for $\approx$ 53,000 spirals. Systematic errors arise if the photometric PA differs from the kinematic PA from velocity fields. We quantify systematic uncertainties in DESI-TF dista…

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astro-ph.SR

Fine-scale flare structures and their energetic implications from short-exposure extreme-ultraviolet imaging

Laura A. Hayes, Hannah Collier, Säm Krucker, Daniel Ryan, David Berghmans, Emil Kraaikamp, Muriel Stiefel, Andrew Inglis et al.

To capture the brightest and most rapidly evolving phases of solar flares, the Major Flare Solar Orbiter Observing Plan employed a dedicated short-exposure mode for the High Resolution Imager at 174 Angstrom (HRIEUV) of the Extreme Ultraviolet Imager. We investigate the spatial and temporal organisation of compact emission in the 19 March 2024 M2.1 flare using high-cadence, short-exposure HRIEUV observations. We combine these 0.04 s observations with hard X-ray timing, imaging, and spectroscopy…

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astro-ph.SR

Numerical modelling of recombination-driven stellar winds

Bestin James, Jiří Krtička

Low-temperature stars have a significant population of neutral hydrogen increasing with height in their atmospheres. This suggests eventual recombination as we move away from their deep photospheric layers. Recombination can potentially drive stellar winds, particularly in cool and evolved stars. We aim to verify the possibility of stellar winds driven by recombination. We also aim to constitute an initial model for this type wind driving. We examine the possibility of recombination-driven outfl…

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

Path to Black Hole Astrometric Microlensing from 10-Year KMTNet Database

Andrew Gould

I present a Fisher analysis of the astrometric signature of black holes (BHs) that may lie in the 10-year KMTNet microlensing database, motivated by the recent success of the pilot study by Segev et al. (2026), which reduced the scatter at $I=18$ to $σ\sim 10\,$mas. Seeing-limited ground-based observations still suffer from a great deal of systematics, but under the assumption that these systematics can be controlled, I find that with this nominal precision, the Einstein radius can be measured w…

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astro-ph.SRastro-ph.HE

Diversity of stripped-envelope supernova light curves from interaction with binary-driven circumstellar material

Dandan Wei, Fabian R. N. Schneider, Philipp Podsiadlowski, Takashi J. Moriya, Eva Laplace

A growing number of core-collapse supernovae (CCSNe) exhibit diverse light-curve morphologies that indicate strong interaction with dense, pre-existing circumstellar material (CSM). Understanding the physical origin of such CSM is essential for exploring the late-stage evolution of SN progenitors. Non-conservative mass transfer during binary interactions provides a promising channel for producing dense CSM before core collapse. Using the stellar evolution code MESA, we simulate post-common-envel…

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astro-ph.IM

Microscopy assessment of two multiple-transient candidates

Jun Yang, Beatriz Villarroel

We present a microscopy-based assessment of two representative cases of multiple-transient candidates identified on historical photographic plates: the nine-transient event of 12 April 1950 (XE325) and the triple-transient event of 19 July 1952 (XE186). These events consist of spatially clustered, point-like sources detected within single long-exposure plates, lacking the streaks expected from moving objects and therefore suggestive of short-duration flashes. We analyse microscopy images of the…

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astro-ph.COastro-ph.IMcs.LGphysics.data-an

Cross-simulator transfer with foundation model summaries: Towards robust SKA-era reionization inference

Yannic Pietschke, Caroline Heneka, Ayodele Ore, Romain Meriot

Simulation-based inference (SBI) for parameter estimation is vulnerable to model misspecification: neural summaries and density estimators trained on a specific forward model typically fail when applied to data drawn from another model, or from real observations, and no training simulator can capture the full observational pipeline of a real measurement exactly. We show that a self-supervised Vision Transformer (ViT), pretrained label-free on a fast approximate simulator, produces transferable d…

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astro-ph.GA

COSMOS-Web: From early star-formation enhancement to late suppression in galaxy groups

R. C. Arango-Toro, C. Laigle, J. Lewis, M. Joly, G. Toni, C. M. Casey, J. S. Kartaltepe, M. Shuntov et al.

Galaxy groups trace dense environments where interactions, gas removal, and reduced accretion may drive quenching. Common diagnostics trace star formation over short timescales ($\lesssim 100$ Myr), so time-resolved star formation histories (SFHs) are needed to separate brief changes from longer-term evolution at fixed mass and redshift. Using COSMOS-Web data, we test how group environment correlates with star formation, how this evolves with cosmic time and group-centric distance, and how high-…

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astro-ph.COastro-ph.IM

HOLISMOKES -- XVIII. Cosmology with strongly lensed type II supernovae: Effects of instrumental setups on $H_0$

J. Grupa, S. Taubenberger, S. H. Suyu, D. Sluse, S. Huber, C. Vogl

The upcoming Rubin Observatory and subsequent follow-up observations should improve the determination of the Hubble constant ($H_0$) via time-delay cosmography of strongly lensed type II supernovae (LSNe II), by enabling the detection of many more such events. In our previous work, we developed a method for determining the supernova (SN) phase from spectral absorption features. Because obtaining spectra of faint targets such as distant SN II is expensive, we examined how low-resolution spectra i…

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astro-ph.IMastro-ph.CO

RadialPaths: Radial profiles in multi-centred astronomical structures

Rafael S. de Souza

Radial profiles are routinely used to locate structural changes within resolved astronomical systems, but they generally define radial position relative to a single centre. In interacting, clumpy, or otherwise multi-centred structures, the radial location assigned to a feature can depend on the adopted centre. We introduce a centre-conditioned radial representation for connected structures with multiple centres. Distances are measured through the observed source footprint rather than across excl…

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astro-ph.IMastro-ph.COastro-ph.EPastro-ph.SR

The MegaWave Radio Surveyor

T. Joseph W. Lazio, Evgenya Shkolnik, James Aguirre, Stuart D. Bale, Judd Bowman, Ruby Byrne, Joseph Callingham, Tracy E. Clarke et al.

Several Decadal-level questions in astrophysics, exoplanets, astrobiology, and cosmology can be addressed only at low radio frequencies inaccessible from Earth. The MegaWave Radio Surveyor would open this largely-unexplored region of the electromagnetic spectrum with a space-based interferometer to (1)~Track the space weather of other stars; (2)~Detect magnetically-generated emission from exoplanets to probe their interiors and assess magnetic shielding of their atmospheres; (3)~Probe the Univer…

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astro-ph.IMastro-ph.COastro-ph.EPastro-ph.SR

The MegaWave Radio Surveyor

T. Joseph W. Lazio, Evgenya Shkolnik, James Aguirre, Stuart D. Bale, Judd Bowman, Ruby Byrne, Joseph Callingham, Tracy E. Clarke et al.

Several Decadal-level questions in astrophysics, exoplanets, astrobiology, and cosmology can be addressed only at low radio frequencies inaccessible from Earth. The MegaWave Radio Surveyor would open this largely-unexplored region of the electromagnetic spectrum with a space-based interferometer to (1)~Track the space weather of other stars; (2)~Detect magnetically-generated emission from exoplanets to probe their interiors and assess magnetic shielding of their atmospheres; (3)~Probe the Univer…

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astro-ph.EP

Non-equilibrium condensation of the first Solar System solids

Sebastien Charnoz, Jérome Aleon, Marc Chaussidon, Paolo Sossi, Yves Marrocchi, Patrick Franco

Primitive meteorites (chondrites) consist of an out-of-equilibrium assemblage of minerals formed during the assembling of our Solar Nebula. The conditions under which their precursors condensed remain unclear as a result of subsequent re-processing in the protoplanetary disk or in asteroidal parent bodies. Chondrites are classified into three main classes enstatite (EC), ordinary (OC), and carbonaceous (CC) distinguished by different bulk composition and oxidation state. While equilibrium conden…

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astro-ph.SR

Active nests at solar maximum: How nested flux emergence dominated flaring activity and structured the heliosphere

Adam J. Finley, Allan Sacha Brun, Antoine Strugarek, Barbara Perri, Daniel Müller, Miho Janvier, Andy S H To, Henrik Eklund et al.

Multi-viewpoint observations from near-Earth satellites and ESA's Solar Orbiter enable a global view of the Sun. This continuous coverage is essential for characterising active nests. We investigated how the formation of active nests during the maximum of solar cycle 25 affected the Sun's flaring activity and large-scale magnetic field. Active nests were identified from their persistent activity in Carrington coordinates. For each nest, we monitored the evolution of their photospheric magnetic f…

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astro-ph.GA

Phase-Space Diagnostics for Dwarf Galaxies in Cluster Environments

Anna Ivleva, Rhea-Silvia Remus, Klaus Dolag, Lucas M. Valenzuela, Jonah S. Gannon, Duncan A. Forbes

Ongoing effort is devoted to observing spectroscopic samples of dwarf galaxies in clusters, allowing the analysis of their distribution and associated trends in projected phase-space (PPS), i.e. line-of-sight velocity vs. projected clustercentric distance. By utilizing the resolved baryonic halos inside the galaxy clusters of a cosmological simulation from the Magneticum suite, we complement on prior studies with dedicated focus on the dwarf galaxy population ($M_\ast<10^9\,M_\odot$) and correla…

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astro-ph.HE

Synchrotron self-Compton Reverse Shock in Energy-Injection and Radiative Scenarios

Fraija Nissim, Betancourt-Kamenetskaia Boris, Galván Antonio, Dainotti Maria Giovanna

Gamma-ray bursts (GRBs) are among the most energetic extragalactic transients, providing a unique laboratory to investigate the physical origin of the diverse morphologies observed in high-energy light curves and spectra. These morphologies, interpreted through synchrotron and synchrotron self-Compton (SSC) closure relations (CRs), may depend on the circumburst density profile, energy injection, and the dynamical evolution of the reverse shock in the adiabatic or radiative regime. We derive the…

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astro-ph.COastro-ph.IMhep-exhep-phphysics.ins-det

Paleo-Detectors as a Novel Probe of Dark Matter-Nucleus Effective Interactions

Dionysios P. Theodosopoulos

Paleo-detectors are a proposed approach to the direct detection of dark matter (DM) based on the observation of DM-induced nuclear recoils. Rather than relying on large detector masses required for conventional detectors, paleo-detectors exploit extremely long integration times, using small samples of naturally occurring minerals that have resided deep underground and accumulated damage tracks over geological timescales of order a gigayear. In this contribution, we review recent theoretical pred…

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astro-ph.HE

Using CFHT's SITELLE to Probe the Long-Sought Supernova Remnant Shell in the Crab Nebula

Lucas V. da Conceição, Janette Suherli, Samar Safi-Harb, Carter Rhea, Ivo R. Seitenzahl, Ashley J. Ruiter

We present deep, wide-field integral field spectroscopy of the Crab nebula obtained with the imaging Fourier transform spectrometer SITELLE at the Canada--France--Hawaii Telescope (CFHT), to search for the long-sought forward shock. Our observations target the coronal line [Fe XIV]$λ$5303, a tracer of shock-heated gas, over two $11^{\prime} \times 11^{\prime}$ fields that probe projected radii of $\sim$2.4--10~pc west of the pulsar, encompassing the range in which a supernova shell is expected.…

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gr-qcastro-ph.HEhep-th

Effects of the interaction of dark matter and neutron-star matter on extreme and intermediate mass-ratio inspirals

Benjamin A. Wade, Julian Heeck, David A. Nichols

Extreme and intermediate mass-ratio inspirals in a dense dark-matter distribution have the effects of the dark matter imprinted on the orbital dynamics of and the emitted gravitational waves from these systems. Prior work has shown that space-based gravitational-wave detectors can measure the dark-matter-induced effects on the gravitational waves, which would give evidence for the presence of dark matter around the massive black hole. In this earlier work, the dark matter has been assumed to hav…

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astro-ph.GA

The origin of the stellar mass-size relation of satellite galaxies in the COLIBRE simulations

Bruno M. Celiz, Julio F. Navarro, Joop Schaye, Mario G. Abadi, Alejandro Benitez-Llambay, Evgenii Chaikin, Carlos S. Frenk, Filip Huško et al.

We study the stellar mass-size relation of satellite galaxies in the COLIBRE suite of cosmological hydrodynamical simulations. Satellites deviate from the relation that holds for centrals galaxies, where at the high mass end, $\log (M_*/{\rm M}_\odot) > 10.5$, sizes (defined as the 3D half-mass radius $r_{\rm h,*}$) increase systematically with mass ($r_{\rm h,*} \propto M_*^{0.5}$), whereas at lower masses, $8 < \log(M_*/{\rm M}_\odot) < 10.5$, the relation flattens and galaxy size becomes, on…

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astro-ph.COastro-ph.GA

Assembly bias from nuisance to probe II: Salvaging linear clustering from DESI and SDSS data

Nelson Padilla, Dante Paz, Iván Lacerna

Galactic conformity links the properties of neighbouring galaxies and is usually interpreted as a signature of assembly-biased galaxy occupation. We study projected and redshift-space compensated conformity statistics in colour-selected DESI BGS and SDSS MGS samples. These combine correlations of related galaxy populations, suppressing shared nonlinear clustering contributions while retaining a differential large-scale response. We test whether this exposes the linear matter correlation-function…

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astro-ph.GA

A Broken Clock Is Right Twice a Day: [Ce/Mg] Is Not a Universal Chemical Clock

Liam O. Dubay, Jennifer A. Johnson, James W. Johnson, Keith Hawkins, Sofia Feltzing, Natalie R. Myers, Adrian M. Price-Whelan, Tawny Sit et al.

The ratio of $s$-process to $α$-element enrichment ($[s/α]$) has been proposed as a ``chemical clock,'' or a means to estimate stellar ages. However, the age--$[s/α]$ relation varies with metallicity and location in the Galaxy, and the observed trends are not well predicted by galactic chemical evolution models. We quantify the age--[Ce/Mg] correlation across the Galactic disk in roughly 100,000 red giant stars observed with APOGEE in the SDSS-V Milky Way Mapper survey. We find that the slope of…

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astro-ph.GAastro-ph.CO

Barren but not Empty: The Impact of Void Environments on Galaxy and Halo Populations

Anita M. Schiller, Benjamin A. Seidel, Rhea-Silvia Remus, Lucas C. Kimmig, Klaus Dolag

The combination of gravitational collapse and an accelerating expansion of the Universe drive an increasing fraction of volume toward becoming low-density voids across cosmic time. These regions present a unique environment due to their low density, which leads to them behaving similarly to "pocket universes" with modified cosmological parameters. Since the formation and evolution of galaxies is strongly tied to the environment, we aim to discern how voids alter halos and galaxies compared to th…

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