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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.IM

Liquid nitrogen pre-cooling system for ELT instruments utilizing additively manufactured heat exchangers, integrated temperature and liquid level control

Anastasios Aretos, Younes Chahid, Lee Chapman, Mark Cliffe, Maia Jones, Scott McPhee, Chris Miller, Graham Wilks et al.

Using liquid Nitrogen as the cryogenic fluid for pre-cooling purposes is almost ubiquitous across modern observatories. That method tends to be inefficient since it relies on the evaporation of the fluid afforded by the available surface area within the exchanger without capturing any of its latent heat. An additively manufactured heat exchanger could address that inefficiency by providing an increased evaporation area as well as internal structures that can interact with Nitrogen in its gaseous…

astro-ph.SRphysics.ao-phphysics.flu-dyn

Turbulent Convection: Modal Equations and Energy Pathways

S. Sridhar, Nishant K. Singh

We present a framework for studying high Rayleigh number turbulent convection to better understand stellar and planetary convection zones. Utilizing the statistical symmetries of the fully developed turbulent state of Boussinesq convection, we identify relevant mean and fluctuating quantities. After validating these symmetry assumptions through numerical simulations, we formulate the governing equations. Vertical profiles of key physical quantities in the saturated turbulent state are explored i…

astro-ph.HEgr-qc

Spectral densification and macroscopic phase delay of gravitational echoes from exotic compact objects

Corentin Guigot

Gravitational-wave echoes from Exotic Compact Objects (ECOs) provide an observable probe for horizon-scale physics. Standard phenomenological models for these signals typically assume a constant Free Spectral Range, relying on the geometric optics approximation. In this work, we demonstrate that wave dispersion at the photon sphere induces a systematic deviation from this assumption, manifesting instead as a hyperbolic spectral densification. By employing an analytical framework based on the Ric…

hep-phastro-ph.HEhep-ex

Rare processes in ultrahigh-energy tau-lepton transport

Guo-yuan Huang

In cosmic neutrino observatories, charged-lepton transport is a key input for interpreting observables and reconstructing neutrino events. Charged leptons propagating through matter undergo several energy loss processes, such as electron pair production and photonuclear interaction. In this work, we investigate several rare processes in tau-lepton transport, focusing primarily on muon pair production, $τN \to τμ^+μ^- N$, and Primakoff neutral-pion production, $τN \to τπ^0 N$. At EeV energies, we…

astro-ph.IMastro-ph.SRphysics.space-ph

The CUSP CubeSat mission for space weather multi-physics analysis, design, and testing

Giovanni Lombardi, Riccardo Di Spirito, Sergio Fabiani, Daniele Censi, Giovanni De Cesare, Ettore Del Monte, Riccardo Campana, Enrico Costa et al.

The CUbesat Solar Polarimeter (CUSP) mission aims to measure the linear polarization of solar flares in the hard X-ray band by means of a Compton scattering polarimeter. CUSP is a project in the framework of the Alcor Program of the Italian Space Agency aimed at developing new CubeSat missions. We present the outcomes of the CUSP's Phase B study, which is ended on 2 July 2026. The design solutions adopted for the mission's most critical multi-physics design drivers will be discussed, these solut…

astro-ph.SR

Pulsations along the Asymptotic Giant Branch (AGB): a global view

Pierre Darriulat, Pham Thi Tuyet Nhung, Do Thi Hoai

In three preceding articles, we studied the relation between the light curves of Mira variables and their stellar properties. The analysis was restricted to a sample of stars offering high density and quality of observations in the visible, allowing for the definition of simple parameterizations of the light curves. Clear relations were revealed between the evolution of the stars along the AGB and parameters such as the width of the light pulse or the deviation of its ascending branch from a sin…

astro-ph.HEastro-ph.IM

Joint X-ray and gamma-ray analysis at the photon level: Application to MSH 15-52

Katharina Egg, Alison M. W. Mitchell

Joint analysis of multi-wavelength (MWL) data at the level of photon events is challenging, but it provides a statistically preferable method of fitting the data, in contrast to fitting derived flux points. Data from X-ray and gamma-ray instruments are well-suited for a joint description, due to their common physical origin (same particle population and non-thermal processes) and incidentally also due to the high similarity of their formats. Such a description is especially desirable for objects…

astro-ph.EPastro-ph.SRphysics.flu-dyn

Tidal dissipation in magnetised, rotating stars and planets: linear calculations exploring various magnetic field configurations

Shijun Chu, Zhao Guo, Aurélie Astoul, Adrian J. Barker, Rainer Hollerbach

We study tidal flows in the convective envelopes of rotating, magnetised fluid bodies, such as low-mass stars and giant planets. In well-mixed convective regions, (magneto-)inertial waves are linearly excited by tidal forcing, and their dissipation can dominantly drive spin and orbital evolution in many close star-planet and binary star systems. We perform linear magnetohydrodynamic calculations of wavelike tides in spherical-shell geometry of a tidally-forced, rotating, incompressible, viscous…

astro-ph.HE

Polar cap plasma loading and the morphology of pulsar $γ$-ray light curves

Jérôme Pétri

The discovery of more than 300 $γ$-ray pulsars by the Fermi Large Area Telescope (Fermi-LAT) has revealed a rich diversity of light-curve morphologies that remains challenging to reproduce within purely magnetospheric emission models, suggesting that particle acceleration and radiation may occur, at least in part, in the striped-wind current sheet. We compute a comprehensive atlas of pulsar $γ$-ray light curves based on the split-monopole current sheet geometry, with the goal of quantifying the…

astro-ph.HE

Optical Images of the Braneworld Black Hole Surrounded by an Optically Thin Accretion Disk

Wen-Hao Deng, Sen Guo, Qing-Quan Jiang, Kai Lin, Pei Wang

This work examines the observational signatures of rotating black holes with tidal charge in the Randall--Sundrum braneworld scenario. Combining an elliptic-integral-based analytical treatment with numerical ray tracing, we characterize photon motion around braneworld black holes in detail. For small observer inclinations, secondary images remain embedded inside the primary emission rings. As the inclination becomes larger, the primary and secondary images gradually separate and produce a strong…

astro-ph.IM

HARMONI at ELT: Developing a Modular Review Process using TRIZ

Amelia Calderhead, Anna MacIver, David Isherwood, Andy Born, James Stevenson

HARMONI is the first light, adaptive optics assisted, near-IR integral field spectrograph for the ELT. It covers a spectral range from 800nm to 2450nm with resolving powers from 3000 to 7000 and spatial sampling of 25mas and 6mas. It can operate in two adaptive optics modes - SCAO (including a high contrast capability) and MCAO. The project is resuming its final design phase after a rescope design phase in 2025. The HARMONI team at UKATC have been pioneering the use of TRIZ by managing monthly T…

astro-ph.GAastro-ph.HE

Reincarnations of massive stars in active galactic nucleus discs

Jing-Tong Xing, Tong Liu, Jiao-Zhen She

The origin and evolution of massive stars in active galactic nucleus (AGN) discs remain uncertain. We develop a semi-analytical model that follows the evolution of an embedded core-collapse supernova (CCSN) remnant and the subsequent formation and growth of a compact gas cloud. In the dense disc environment, efficient radiative cooling can strongly compress or bypass the Sedov-Taylor stage and drive the remnant rapidly into radiative snowplow evolution. After the remnant loses its interior press…

astro-ph.EP

A Physically Driven Parameterisation of Multidimensional Atmospheres: Application to the JWST Phase Curve of WASP-121b

Yuanheng Yang, Guo Chen, Xianyu Tan, Thaddeus D. Komacek, Xi Zhang, Thomas M. Evans-Soma, Fei Yan, Chengzi Jiang et al.

Understanding the multidimensional structure of strongly irradiated exoplanets is essential for interpreting their atmospheric dynamics, chemistry and energy transport, yet current analyses remain limited by the difficulty of extracting reliable phase-resolved spectra and by the lack of physically interpretable parameterisations for retrievals. We combine a data-driven eclipse-normalisation method with an analytical three-dimensional temperature parameterisation derived from radiative, advective…

astro-ph.GAastro-ph.SR

The Open Cluster Chemical Abundances and Mapping Survey XI. First Gradients from SDSS/MWM BOSS Determined Clusters

Jonah M. Otto, Peter M. Frinchaboy, John Donor, Ilija Medan, Natalie R. Myers, Audrey Hauck, Katia Cunha, Gail Zasowski et al.

The Milky Way Mapper program in the fifth generation of the Sloan Digital Sky Survey (SDSS-V/MWM) has observed millions of stars, thousands of them in open clusters. The Open Cluster Chemical Abundances and Mapping (OCCAM) survey continues to create comprehensive datasets of open clusters and their members in order to constrain Galactic parameters. This eleventh contribution from the OCCAM survey is the first to use stellar parameters from stars observed with the optical Baryon Oscillation Spect…

astro-ph.EPastro-ph.SR

Asymmetric, variable H$α$ line profile in planetary mass object SR 12 c

Jun Hashimoto, Yuhiko Aoyama, Michihiro Takami, Shinsuke Takasao

Young, forming planetary-mass objects often exhibit clear signatures of ongoing mass accretion and are thought to accrete material through processes analogous to those operating in young stars. In this study, we present high-spectral-resolution observations of asymmetric and time-variable H$α$ line profiles from the planetary-mass companion SR~12~c. The H$α$ line was observed at a resolving power of $R \sim 49,000$--40{,}000 (corresponding to 6.1--7.5~km~s$^{-1}$) using the High Dispersion Spect…

astro-ph.SRphysics.atom-ph

A New Approach to Modeling Line Shapes with Quasi-H$_2^+$ Satellites in Stellar Atmospheres

Jackson R. White, Thomas A. Gomez, Mark C. Zammit, Michael H. Montgomery, Bart H. Dunlap, Ivan Hubeny, Dmitry V. Fursa, Igor Bray et al.

Theoretical spectral line shapes describe the distribution of opacity due to bound electronic transitions in hot dense plasmas and are used to fit emergent spectra from many astrophysical sources. Deficiencies in line broadening theory have been proposed as a possible explanation for unresolved discrepancies between theoretical and observed spectra in white dwarf star atmospheres and laboratory experiments at white dwarf star photosphere conditions. One possible source of these discrepancies is…

astro-ph.HE

Strongly Magnetized Super-Eddington Accretion: How Spin and Accretion Rate Regulate Energy Output and Mass Loss

Tom Man Kwan, Lixin Dai, Cheuk Kwan Kan, Zepei Xing, Tassos Fragos, Matthew Middleton, Tao Ji, Feng Yuan et al.

Strongly magnetized super-Eddington accretion flows power many important astrophysical systems, but how black hole parameters control their output is unclear. We present 32 general relativistic radiation magnetohydrodynamics simulations of super-Eddington magnetically arrested disks onto stellar-mass black holes, varying mass ($M_{\rm BH}= 5, 15, 30\,M_{\odot}$), spin ($a=0,0.9$), and accretion rate ($\dot{M}_{\rm acc} \approx 1-2000\,\dot{M}_{\rm Edd}$). We find that black hole spin and accreti…

astro-ph.IM

On-sky results from REDWOODS, a platform at Lick/ShaneAO for testing second stage AO technologies

Benjamin L. Gerard, Dominic F. Sanchez, Aditya R. Sengupta, Chris Ratliff, Sylvain Cetre, Elinor Gates, Daren Dillon, Bautista Fernandez et al.

REDWOODS is a new sub-testbed within the Shane Adaptive Optics (AO) system at Lick observatory, developed to test second stage AO wavefront sensing and control technologies, including a Self-Coherent Camera with optional broadband Wynne corrector, two different three-sided fully reflective highly broadband pyramid wavefront sensor modes, and multi-wavefront sensor single conjugate AO control. We present project results to date, including on-sky data.

astro-ph.GA

Determining Total Infrared Luminosities from Submm Measurements of High Redshift Galaxies

Maria Emilia De Rossi, George H. Rieke, Christina C. Williams, Volker Bromm, Jianwei Lyu, Meredith A. Stone, Yang Sun, Christopher N. A. Willmer et al.

Determining total infrared luminosities for very high redshift galaxies is important to estimate the rate of star formation in heavily dust-embedded environments. It is also challenging because the most sensitive far infrared observatory, Herschel, was limited in sensitivity and its deepest measurements are subject to confusion noise. Thus, these determinations largely depend on ALMA, observing in the mm- and/or submm-wavelengths, which sample only the long-wavelength part of the spectral energy…

astro-ph.SR

Quasi-Keplerian Be-Star Disks with Mimicking Viscosity

Michel Cure, Ignacio Araya, Rodrigo Meneses, Matias Montesinos, Roberto O. J. Venero, Catalina Arcos, Abigali Rodriguez, Lydia S. Cidale et al.

Classical Be stars are fast-rotating B-type stars with gaseous quasi-Keplerian disks formed by equatorial ejection of material. While the viscous decretion disk (VDD) model reproduces many observed properties, the role of radiative line driving in shaping these disks remains unclear. We investigated the combined influence of viscosity and radiative acceleration on the hydrodynamic structure of Be star disks by coupling the m-CAK theory of line-driven winds with a mimicking viscous prescription g…

astro-ph.HEhep-ph

Energy-dependent Optical/Near-infrared and X-ray Correlations in Swift J1727.8-1613

Ruican Ma, Federico Vincentelli, Diego Altamirano, Alexandra Veledina, Poshak Gandhi, Piergiorgio Casella, Tariq Shahbaz, Sian Woahene-Demehin et al.

We present a timing analysis of the black hole transient Swift J1727.8-1613 during its intermediate state. We use coordinated broadband X-ray observations from Insight-HXMT (2-150 keV), together with optical data from ULTRACAM (g_s and i_s bands) and near-infrared data from HAWK-I (K_s band), obtained on 2023 September 9. As shown by previous studies, the Fourier power spectrum shows a strong quasi-periodic oscillation (QPO) in the K_s, i_s and X-ray bands. Cross-correlation analysis reveals a c…

astro-ph.EPastro-ph.IM

Optical and acoustic ground effects simulations from terminal defense asteroid disruption via the PI method

Brin Bailey, Alexander N. Cohen, Philip Lubin, Darrel K. Robertson, Mark Boslough, Sasha Egan, Elizabeth A. Silber, Dharv Patel et al.

Our simulations suggest that PI ("Pulverize It"), a NASA Phase II NIAC study, is an effective multi-modal approach for planetary defense that can operate in extremely short interdiction modes (with intercepts as short as hours prior to atmospheric entry) as well as long interdiction time scales with months to years of warning. The basic process is complete disruption of the threat via fragmentation. In scenarios with sufficiently long warning time, the fragment cloud spreads enough to miss Earth…

astro-ph.GAastro-ph.SR

EWOCS-VIII: Internal kinematics and expansion of Westerlund 1 from VVVX proper motions

C. Ordenes-Huanca, A. Bayo, M. Guarcello, M. Zoccali, A. Rojas-Arriagada, Nicholas J. Wright, S. Sciortino, F. Damiani et al.

Westerlund 1 (Wd1) is the most massive young star cluster known in the Milky Way and a key laboratory for studying the early dynamical evolution of massive clusters. Owing to its high extinction, the internal kinematics of its intermediate-mass stellar population remain largely unexplored. We aim to characterize the internal kinematic properties of Wd1 using a homogeneous census of near-infrared (NIR) selected cluster members and their proper motions (PMs). We considered PMs from the VIRAC2 cata…

astro-ph.IM

LUVCam: A high-performance, low-cost, UV/optical camera for the future of astronomy in space

Aaron Tohuvavohu, Suresh Sivanandam, Jean-Christophe Fronteddu, Patrick Nkwaria, Gavin Hay, Shaojie Chen, Sarik Jeram, Albert Lau et al.

Astronomy-grade cameras with robust performance and heritage in the space environment have long been costly, substantially limiting capacity for space-based astronomy and creating a resource barrier to access. Additionally, ultraviolet observations have historically been limited by the low quantum efficiency of most sensors in this wavelength range. The LUVCam program is designed to address both issues by providing a high-performance, low-cost, UV/optical camera system sufficiently capable to su…

hep-phastro-ph.HE

Molecular clouds constraints on sub-GeV DM and asteroid-mass PBHs

Asier Salces Pérez, Pedro de la Torre Luque

We show that the ionization of molecular clouds provides a novel probe of dark matter scenarios producing low-energy $e^+e^-$ pairs through annihilation, decay, or Hawking evaporation of primordial black holes. We derive constraints on MeV-scale dark matter with masses between $\sim1$ and $100$ MeV, as well as on primordial black holes in the mass range $10^{14}$--$10^{17},$g. By modeling the propagation of electrons and positrons inside molecular clouds, we show that uncertainties in charged-pa…

astro-ph.IM

Multi-sensor fusion for fine-guidance and milliarcsecond-level attitude estimation of balloon-borne telescope

Philippe Voyer, Maya Amit, Steven J. Benton, Benjamin E. Boyd, Anthony M. Brown, Giulia Cerini, Paul Clark, Matthew Craigie et al.

Balloon-borne telescopes rely on fine-guidance systems to achieve milliarcsecond image stability despite residual disturbances from the balloon environment. In these systems, the Fast Steering Mirror (FSM) stabilizes the image in two focal-plane axes, but leaves systematic, field-dependent residual motion induced by boresight roll. This effect, referred to as roll leakage, becomes more important for wider fields of view. In this work, roll leakage is characterized using data from the 2023 Superp…

astro-ph.GA

SDSS-V Local Volume Mapper (LVM): The Integrated Light and Internal Rotation of Omega Centauri

Maximilian Häberle, Dmitry Bizyaev, Alina Boecker, Callie Clontz, Bruno Dias, Antoine Dumont, Evgeniya Egorova, Anja Feldmeier-Krause et al.

The SDSS-V Local Volume Mapper (LVM) is a wide-field integral field spectroscopic survey of the Southern Milky Way plane, the Magellanic Clouds, and nearby Local Group galaxies. We use Early Science observations of the whole body of the nearest nuclear cluster, Omega Centauri, to extend the LVM beyond its primary interstellar-medium science case. The wide LVM field allows us to precisely map $ω$ Cen's line-of-sight rotation out to $\sim 3r_{HL}$ or $15^\prime$, reaching a maximum value of $(8.4…

astro-ph.SRphysics.space-ph

Averaging Effects on the Solar Wind Alfven Mach Number: Implications for Switchbacks and Alfven Transition

Joshua Goodwill, Subash Adhikari, Francesco Pecora, Rayta Pradata, Jiaming Wang, Sujan Prasad Gautam, Manuel E. Cuesta, Orlando Romeo et al.

Averaging techniques in solar wind measurements have been a longstanding subject of debate. Using Parker Solar Probe (PSP) observations from encounters 1 to 19, we investigate how averaging timescales influence the characterization of turbulent properties across the Alfvenic transition. We compute the rolling mean Alfven Mach number over various averaging intervals, which are then analyzed against switchbacks, magnetic fluctuation energy, and correlation time. We find that the distribution of su…

astro-ph.GA

Fishing for Jellyfish Galaxies: Exploring ram-pressure stripping with crowd science

C. Bellhouse, Y. L. Jaffé, J. P. Crossett, S. L. McGee, Ignacio Quiroz, C. Dulcien, R. Smith, B. M. Poggianti et al.

Aims: We present the first results of Fishing for Jellyfish Galaxies, a pilot citizen-science project using Zooniverse to identify galaxies undergoing ram-pressure stripping (RPS). Methods: Volunteers visually inspected colour images of late-type galaxies from the Dark Energy Camera Legacy Survey, from a sample of 49,703 galaxies selected within $4 \times R_{500}$ of clusters and groups, restricted to galaxies brighter than 19th magnitude in the g and r bands, and with a minimum half-light radiu…

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

Cataclysmic variables from Gaia XP spectra: The Gaia emission-line magnitude (GEM) diagram

Ilkham Galiullin, Vladislav Dodon, Antonio C. Rodriguez, Askar Sibgatullin

Gaia DR3 opens a new window for the census of Galactic stellar populations in all-sky surveys, specifically for identifying cataclysmic variables (CVs). While the majority of CVs are distributed below the main sequence on the Gaia HR diagram, identifying them among dominant background stellar populations remains a significant challenge. Here, we present the Gaia Emission-line Magnitude (GEM) diagram - a tool designed to isolate CV candidates from background stars located below the main sequence.…