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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.HE

High-Resolution Numerical Calculations of GRB Afterglow Plateaus arising from Stratified Ejecta

Paul C. Duffell, Ranadeep Ghosh Dastidar

Since the discovery of plateaus in GRB afterglows by Swift, they have been modeled predominantly by late-time energy injection. However, many studies have suggested that the plateau may be modeled by an early phase before reverse shock crossing (either coasting with constant Lorentz factor or decelerating very slowly as the reverse shock crosses the ejecta). The slope of the early plateau provides some constraints the stratification of the fastest-moving ejecta, which could be the ejecta respons…

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astro-ph.GA

Dynamical modelling of giant radio quasars in the HETDEX Spring Field

T. M. O. Franzen, J. Machalski, M. Jamrozy, R. Morganti, D. A. Green, Y. C. Perrott, T. W. Shimwell

Giant radio sources are defined as extragalactic radio sources, hosted by galaxies or quasars, with linear sizes $\geq 0.7$ Mpc. They are thought to represent the final stage of the evolution of radio galaxies whose sizes range from pc to Mpc scales. We analyse in detail the radio morphology and spectra between 54 MHz and 4.85/15.5 GHz of 15 giant radio quasars (GRQs) in the HETDEX Spring Field, and fit dynamical evolution models to the sources' observational properties to study their physical p…

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astro-ph.IM

Fast and accurate bandpass integration of complex SEDs with neural networks

L. A. Bianchi

The paper presents a novel ML-based approach for fast and accurate bandpass integration of spectral energy distributions (SEDs). The non-locality of the integral operator involved guarantees the smoothness of the target function to be approximated, making it an excellent use-case for neural networks. The computational method developed for this work has been wrapped within pyfine (FINE: Fast Function Interpolation via NEural NEtworks). This new Python package makes the relevant code available and…

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astro-ph.GA

SMA Observations of the Archetypal Compact Steep-spectrum Radio Source 3C 303.1

Rushikesh Bhutkar, Mark Gurwell, Christopher O'Dea, Mojegan Azadi, Belinda Wilkes, Stefi Baum, D. J. Saikia, Grant Tremblay et al.

AGN (active galactic nuclei) feedback plays a crucial role in shaping galaxy evolution. Numerical simulations show that the kinetic energy transfer efficiency from radio jets to interstellar medium (ISM) is relatively high, suggesting a significant role of radio jets in the feedback. We investigate AGN feedback on cold gas in the compact steep-spectrum (CSS) radio source 3C 303.1. CSS sources are largely young radio galaxies evolving through dense environments of their host galaxies. This early…

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astro-ph.SR

Structure and Dynamics of the Inner Corona Measured from the DEB Initiative 2024 Eclipse Image Sequence

Matthew J Penn, Robert Baer, Chris Mandrell, Corinne Brevik, Castor Fu, Mike Conley, Richard Danley, Harvey Henson et al.

The Dynamic Eclipse Broadcast (DEB) Initiative citizen science program observed coronal visible continuum brightness during the 2024 April 8 total eclipse from locations across North America. We present results from 11 DEB sites spanning 2700 km of distance and showing 49 minutes of evolution. The coronal brightness radial profiles from these telescopes are tightly correlated from 1.2 to 4.0 solar radii and comparable to published photometric coronal intensities. The coronal flattening parameter…

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astro-ph.GA

The MAGPI survey: Stellar populations radial trends and mass assembly in star-forming galaxies at z~0.3

Federica Mauro, Bodo Ziegler, Iris Breda, Polychronis Papaderos, Gauri Sharma, Sabine Thater, Katherine E. Harborne, Trevor Mendel et al.

The evolution of galaxies from cosmic noon to the present day provides a key window to probe the balance between early, rapid bulge formation and prolonged disk growth. The epoch at $z \sim 0.3$ marks a crucial transitional phase between the peak of cosmic star formation and the predominantly quiescent local Universe. In this work, we examine the spatially resolved stellar populations of 34 galaxies at $z \sim 0.3$ to quantify radial gradients in age, stellar metallicity, and star formation acti…

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astro-ph.IM

Updates to the WFC3/IR Photometric Stability Stellar Cluster Study

Ky Huynh, Varun Bajaj

The WFC3/IR channel has been shown to lose sensitivity over time. The sensitivity loss rate has been quantified in past works and we extend those measurements into 2026 using photometry of uncrowded regions of star clusters 47 Tucanae and Messier 4 in the F110W and F160W filters. This study adds 4-7 additional visits since Bajaj et al. (2022) for each target/filter combination. Using F160W data of 47Tuc, we find that the IR channel continues to lose sensitivity at a rate of -0.07% $\pm$ 0.01% pe…

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astro-ph.HE

Investigating the Periodic X-ray Behaviour in the Eclipsing AGN NGC 6814

T. O. Hodd, L. C. Gallo, A. G. Gonzalez, J. M. Miller, D. Rogantini

A 2016 XMM-Newton X-ray light curve of the Seyfert 1.5 galaxy NGC 6814 exhibited clear eclipsing behaviour, with distinct ingress and egress, during half of the observation. Here, we report on the periodic behaviour in the light curve prior to the eclipse. We use timing and spectral analysis techniques to quantify the behaviour and examine the characteristics of the periodic signal. A superlet transform of the X-ray light curve reveals a period of ~45-50 $μ$Hz in the initial 60 ks of the observa…

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astro-ph.IM

Establishing baseline model performances for optical turbulence forecasting

M. De Sepibus, E. Masciadri, C. Weinberger, C. Veillet, S. Ragland

Accurate optical turbulence (OT) forecasts help telescopes observe with maximum efficiency, as the performance of adaptive optics (AO) systems strongly depends on turbulence conditions. OT forecasting remains a challenging problem. A wide range of methods has been explored to address this problem, including numerical weather prediction (NWP) models, machine learning algorithms, and hybrid approaches, each varying in complexity, computational cost, and accuracy. Assessing the performance of forec…

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astro-ph.IMastro-ph.EP

Astra: an open-source fully autonomous robotic observatory control software

Peter P. Pedersen, David Degen, Lionel Garcia, Urs Schroffenegger, Daniel Sebastian, Sebastián Zúñiga-Fernández, Brice-Olivier Demory, Elsa Ducrot et al.

Robotic and autonomous observatories are critical for modern time-domain and high-cadence astronomical surveys. The operation of these facilities requires complex software coordination to manage hardware, schedule observations, and ensure safety. However, existing observatory control software are often proprietary and platform-locked or require complex message-brokering infrastructure. Here we present Astra (Automated Survey observaTory Robotised with Alpaca): an open-source, cross-platform Pyth…

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astro-ph.HE

Momentum Space Resolution Dependence in Boltzmann Neutrino Radiation Hydrodynamics Simulations of Core-collapse Supernovae

Ryuichiro Akaho

Finite momentum space resolution is a primary source of uncertainty in solving the Boltzmann equation with the discrete-ordinates method. In this paper, the momentum space resolution dependence of Boltzmann neutrino transport is studied by performing a series of two-dimensional core-collapse supernova (CCSN) simulations. The effects on the explosion dynamics are discussed by individually varying the resolutions of the zenith and azimuth angles in momentum space, and of the energy. It is found th…

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astro-ph.SR

Searching for Stellar Activity Cycles using Flares II: The TESS CVZ

Tobin M. Wainer, Holland M. Stuart, Guadalupe Tovar Mendoza, Andrew R. Casey, Tom Wagg, James R. A. Davenport

Magnetic activity cycles provide a fundamental constraint on stellar dynamos, but remain difficult to identify beyond the Sun. However, recent studies have shown that flares offer a unique tracer of activity cycle behavior. In this study, we use seven years of short-cadence observations from the Transiting Exoplanet Survey Satellite (TESS) for over 14,000 stars in the Continuous Viewing Zone to search for long-term changes in flare activity. For each star, we perform injection and recovery tests…

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astro-ph.IM

The MICADO first light imager for the ELT: the SCAO module AIT in France, from the beta flat configuration towards the flat and final configurations

Yann Clénet, Vincent Lapeyrère, Eric Gendron, Fabrice Vidal, Frédéric Chapron, Mathieu Cohen, Sylvain Guieu, Roderick Dembet et al.

MICADO is the designated ELT first light instrument, a near-infrared imager working at the diffraction limit of the telescope thanks to a SCAO and an MCAO mode. Since summer 2024, MICADO is in its AIT phase and all MICADO partners are currently integrating their subsystems. The MICADO SCAO module will follow three successive AIT phases in France: the beta flat configuration, the flat configuration and the final configuration. In this contribution I will first present the progress made in the AIT…

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astro-ph.SR

K 1-6 is a photoionised ISM nebula shaped by a fast-moving hot white dwarf in a triple system

Jaroslav Merc, David Jones, Ana Escorza, Henri M. J. Boffin, Nicole Reindl, Michael Abdul-Masih, Thomas Masseron, Paulina Sowicka et al.

K 1-6 has long been classified as a planetary nebula (PN) hosting a binary central star, yet it has remained poorly studied due to its faintness. The central star exhibits pronounced photometric variability whose origin has so far been unclear. We aim to present a comprehensive characterisation of the K 1-6 system, including the physical properties of its stellar components and the nature of the surrounding nebulosity. We conducted a multi-wavelength analysis combining optical and UV spectroscop…

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astro-ph.SR

Inferring 3D Coronal Magnetic Fields Through Seismology Assisted Inversions of $IQU$-only Spectropolarimetric Observations

Alin Răzvan Paraschiv

The routine measurements of the Stokes $IQUV$ signals of emission lines in the solar corona is still a challenging endeavor, particularly for observations using small-aperture instruments. Therefore, recent studies have explored the use of coronal seismology and propagating Alfvénic waves as alternative diagnostics of the coronal magnetic field. In particular, Yang et al. (2024) showed that plane-of-sky (POS) phase-speed measurements provide a direct and consistent diagnostic of the POS magnetic…

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astro-ph.SR

Southern massive stars at high angular resolution: WR 25 is a massive hierarchical triple system

K. Deshmukh, L. Mahy, H. Sana, A. J. Frost, E. Gosset, C. Lanthermann, J. -B. LeBouquin, D. Pauli et al.

WR 25 is a massive colliding-wind binary in the Carina nebula comprising a WN6ha primary with an O5 companion in an eccentric 208-d orbit. Recent spectroscopic analysis estimates the total binary mass to approach $100\,M_\odot$, and a primary-to-secondary mass ratio of $q= M_1/M_2\approx2$. The presence of additional spectroscopic signatures from a third, intruder star was also noted, making it a candidate hierarchical triple system. In this study, we present a VLTI/PIONIER interferometric obser…

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astro-ph.IM

The MICADO first light imager for the ELT: an overview of the RAM analysis and consequent design and maintenance strategy

Federico Biondi, Yann Clénet, Patrick Caillier, Veronika Wimmer, Tristan Buey, Luis Neumeier, Florian Lang, Sebastian Rabien et al.

MICADO is a cryogenic near infrared Multi-AO Imaging Camera and Spectrometer developed for the first light operations at the ELT. It will operate in a "Standalone" configuration with a Single Conjugate Adaptive Optics module for a nominal period of two years. After this time, the system will be re-arranged in the "MICADO-MORFEO" configuration, being able to switch between the SCAO and a Multi Conjugate Adaptive Optics module in the later phase of the project. The lifetime requirement of minimum…

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astro-ph.HEastro-ph.GA

EP-FXT Observations of Abell 1795: X-ray Properties and Structure out to $R_{200}$

Y. Tang, S. M. Jia, H. H. Zhao, C. K. Li, H. Yu, Y. Chen, S. S. Weng, X. Y. Zheng et al.

We present deep X-ray observations of the nearby, X-ray luminous galaxy cluster Abell 1795 obtained with the Einstein Probe Follow-up X-ray Telescope (EP-FXT), with a total exposure time of 480 ks. Exploiting the large field of view and low particle background of EP-FXT, we directly measure the radial temperature profile of A1795 out to $R_{200}$ with full azimuthal coverage, which increases with radius within 6 arcmin and then gradually declines toward larger radii. The surface-brightness resid…

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astro-ph.IM

The MICADO first-light imager for the ELT: first steps of the SCAO system MAIT

Yann Clénet, Eric Gendron, Fabrice Vidal, Mathieu Cohen, Frédéric Chapron, Arnaud Sevin, Tristan Buey, Sylvain Guieu et al.

MICADO is the ELT first light instrument, an imager working at the diffraction limit of the telescope thanks to two adaptive optics (AO) modes: a single conjugate one (SCAO), available at the instrument first light and developed by the MICADO consortium, and a multi conjugate one (MCAO), developed by the MORFEO consortium. Although the project final design review process is about to be completed, the review board and ESO acknowledged that "the review of the final design can be considered complet…

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astro-ph.HEcond-mat.stat-mechhep-phphysics.bio-ph

Supernova Neutrinos and the Origin of Biomolecular Homochirality

Amirmasoud Jannat, Soroush Shakeri, Farhad Shahbazi

We investigate the role of parity-violating interactions between supernova neutrinos and chiral molecules in nearby interstellar molecular clouds as a potential source of biomolecular homochirality. We introduce neutrino interactions into the autocatalytic chemical reactions in a far-from-equilibrium noise-induced system. These interactions create a directional bias between L and D enantiomers in the racemization reactions, which is amplified by autocatalysis and stochastic fluctuations. We solv…

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astro-ph.IM

Enhanced wavefront sensing for the Roman Coronagraph Instrument: Gaussian probes and compact model validation

Lukas Delaye, Iva Laginja, Pierre Baudoz, Axel Potier, Johan Mazoyer, Raphaël Galicher, Susan F. Redmond, Alexis Lau et al.

The Coronagraph Instrument on the Roman Space Telescope will be the first space-based system to demonstrate closed-loop focal-plane wavefront sensing and control, a key step towards the Habitable Worlds Observatory. Beyond the baseline Hybrid Lyot Coronagraph, "enhanced modes" are being developed to improve efficiency and science yield. One such mode uses Gaussian probes for electric field estimation, extending the linear regime and allowing higher probe amplitudes. This may increase signal-to-n…

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astro-ph.EPastro-ph.SR

Plasma chemistry and electron-moderated pathways in substellar atmospheres: a new perspective on the L/T transition

Matthew I. Swayne, Declan A. Diver, Craig R. Stark

The long-standing puzzle of the CO/CH$_{4}$ transition in brown dwarfs endures. Although the bulk spectral evolution across an atmosphere can be accounted for through thermal equilibrium cloud models, the behaviour in the NIR remains unaccounted for, indicating that additional, non-thermal processes may influence atmospheric chemistry alongside conventional pathways. We explore cloud-driven electrical activation, where low-energy sparks to full lightning discharges, unlocks non-equilibrium react…

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astro-ph.HE

Identifying potentially missed extended sources in the Fermi-LAT 4FGL Catalog using clustering analysis

Giovanni Cozzolongo, Alison M. W. Mitchell, Samuel T. Spencer, Dmitry V. Malyshev, Tim Unbehaun

Context. Since its launch in 2008, the Fermi Large Area Telescope (LAT) has detected thousands of sources, many of which remain unassociated. Some may be extended sources represented in the catalog by multiple point-like entries. The reinterpretation of HESS J1813-178 as a single extended source motivates a systematic search for further missed extended sources. Aims. We search for clusters of unassociated Fermi-LAT sources and test whether single extended-source models describe them better than…

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gr-qcastro-ph.HEastro-ph.IMphysics.ins-det

Evaluating KAGRA upgrade scenarios for multimessenger observations of binary neutron stars

Yuta Michimura, Soichiro Morisaki, Kenta Hotokezaka, Masaomi Tanaka

Binary neutron star mergers are key targets for multimessenger astronomy, motivating future upgrades of gravitational-wave detectors. For KAGRA, both broadband sensitivity improvements that increase the binary neutron star detection range, and high-frequency optimizations targeting neutron-star physics are under consideration. We present a computationally efficient framework to evaluate the multimessenger performance of detector upgrades by combining Fisher-matrix estimates of localization area…

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astro-ph.IMphysics.hist-ph

A genetic algorithm for peer-review panel composition

Ferdinando Patat

The composition of scientific review panels is a constrained optimization problem in which a finite pool of experts must be distributed among multiple panels while balancing scientific expertise and demographic diversity. As the number of possible panel configurations grows very rapidly with the number of reviewers, exhaustive searches rapidly become computationally impractical. In this paper I present a genetic algorithm designed to optimize panel composition for the European Southern Observato…

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astro-ph.HE

An internal shock model calibrated with real gamma-ray burst light curves using a genetic algorithm

Manuele Maistrello, Cristiano Guidorzi, Shiho Kobayashi, Romain Maccary

The origin of gamma-ray burst (GRB) prompt emission remains an open question. The internal shock (IS) model is a leading scenario for converting relativistic ejecta kinetic energy into gamma rays, but its parameters have not yet been fully calibrated against observed GRB light curves (LCs) to reproduce their diversity. We adopt a machine-learning framework to optimise the IS model by comparing simulated and observed LC properties from three GRB catalogues (Swift/BAT, Fermi/GBM, CGRO/BATSE). Assu…

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astro-ph.HE

Constraining the High-Density Equation of State with Present and Future NICER Observations Using Physics-Informed Regularized Machine Learning

Utkarsh Atul Deshmukh, Asim Kumar Saha, Ritam Mallick

The precise mass and radius measurements of neutron stars by NICER have significantly advanced our ability to constrain the properties of matter at supranuclear densities. In this work, we develop a physics-informed regularized conditional Invertible Neural Network (cINN) that bijectively maps mass--radius posterior distributions directly onto the corresponding central energy density and pressure, eliminating the need for explicit high-dimensional parameter sampling. The physics-informed regular…

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astro-ph.GAastro-ph.HE

Perturber-Driven Dynamics of Supermassive Black Hole Binaries in Galaxy Merger

Julian Chan, Alessia Gualandris, Walter Dehnen, Justin I. Read

The orbital eccentricity of massive black hole binaries (MBHBs) at binary formation shapes the stochastic gravitational-wave background (GWB) detectable by pulsar timing arrays (PTAs). Previous $N$-body simulations show large run-to-run scatter in this quantity, dominated by Poisson noise, raising the question of whether physical substructure adds genuine astrophysical stochasticity. We test this with high-resolution re-simulations of a major merger from IllustrisTNG100-1, evolved with the Griff…

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astro-ph.GAastro-ph.CO

Radar-Chart Analysis of Star-Formation Quenching Stages Across Circular Velocity Curve Classes in Nearby CALIFA Galaxies

Veselina Kalinova, Dario Colombo

We analyze the circular velocity curves of 215 non-active galaxies from the Calar Alto Legacy Integral Field spectroscopy Area survey. Using radar-chart analysis, we compare two classification schemes: the circular velocity curve classification and the quenching classification. We find a systematic progression from slow-rising to flat, round-peaked, and sharp-peaked curves that mirrors the transition from star-forming to fully retired systems. Star-forming galaxies are mainly slow-rising and fla…

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astro-ph.HE

Coupled Shock Cooling and Radioactive Heating in the Type IIb Supernova SN 2024aecx: An Extended Envelope and Rapid Optical Decline

Na Wei, Yu-Hao Zhang, Liang-Duan Liu, Guang-Lei Wu, Jing-Yao Li, Yun-Wei Yu, Ning-Chen Sun

SN~2024aecx is a nearby, rapidly evolving stripped-envelope supernova with a prominent double-peaked ultraviolet--optical light curve. We model its multiband evolution with an extended version of \texttt{TransFit}, in which the early shock-cooling emission and the subsequent radioactive heating are treated within a single time-dependent radiative diffusion calculation. To describe the stratified ejecta expected for a Type~IIb progenitor, we adopt a compact inner ejecta connected to a dilute exte…

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