UchUchU

Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.HEastro-ph.GA

Little Red Dots as Shock-Powered High-Energy Neutrino Sources

Tyco Mera, Chris Ashall, Shunsaku Horiuchi, Rohan Naidu, Kyle Medler, Peter Hoeflich

Little Red Dots (LRDs) are compact, high-redshift sources whose physical nature remains uncertain. Their optical spectra bear many similarities to Type IIn supernovae (SNe IIn), motivating a scenario in which their emission is powered by shocks interacting with dense surrounding material. We investigate whether such interactions can power LRDs and contribute to the diffuse high-energy neutrino intensity measured by IceCube. In our simplified model, a fast central-engine outflow drives a shock th…

Read →
astro-ph.HEhep-exhep-ph

Anomalous horizontal track-like events at the HAWC observatory: candidate neutrino-induced charged leptons from the Pico de Orizaba volcano

Hermes León Vargas, Andrés Sandoval

Two track-like events with exceptionally large charge deposits, pointing back to the region of maximum overburden ($>18$ km.w.e.) of the Pico de Orizaba volcano, were reported by the HAWC Collaboration in a search for Earth-skimming neutrinos. Using exclusively published information, including the published Monte Carlo charge distributions and the scattered-muon background model, we show that these events are kinematically inconsistent with all identified backgrounds. A conservative energy-conse…

Read →
astro-ph.HEastro-ph.GA

A Self-Sustaining Black Hole Engine Powered by the Tidal Disruptions of Stars

James Guillochon, Avi Loeb

Tidal disruption events (TDEs) strongly prefer host galaxies undergoing, or recovering from, a burst of star formation, implying that a rare minority of galaxy types produces most events. The required per-galaxy rates, as high as $10^{-2}$ gal$^{-1}$ yr$^{-1}$, are hard to achieve through stellar relaxation alone. Molecular clouds surrounding nuclear clusters help set the relaxation rate, offering a path to higher rates. We show that (post-)starburst galaxies, whose nearby prototypes contain lar…

Read →
astro-ph.EP

Magnitude of stable iron isotope fractionation limited by multiple stages of terrestrial core formation

Gabriel Nathan, Seth A. Jacobson

One proposed mechanism for generating iron isotopic differences between planetary mantles and chondrites is metal-silicate equilibration during terrestrial core formation. Prior studies of this isotopic fractionation effect employ single-stage core formation models that are inconsistent with reproducing the siderophile element budget of the Earth's mantle. Here, we model iron isotopic evolution of the Earth's mantle in a multistage core formation scenario that is consistent with dynamic models o…

Read →
astro-ph.IMastro-ph.EP

Pre-shipment optical characterization of the SCALES instrument

Isabel J. Kain, Reni Kupke, Daren Dillon, R. Deno Stelter, Rosalie McGurk, Gwendolin Weber-Stover, Athira Unni, Marc Kassis et al.

The Slicer Combined with an Array of Lenslets for Exoplanet Spectroscopy (SCALES) instrument is a 1-5 micron imager and 2-5 micron integral field spectrograph, currently being commissioned on the Keck II Telescope. SCALES is optimized for exoplanet high-contrast imaging and spectroscopic characterization, and will be sensitive to older, colder exoplanets than existing instrumentation. The 12.3" x 12.3" imaging channel is designed to replicate the capabilities of NIRC2, and the low (R~35-200, 2.2…

Read →
astro-ph.HEastro-ph.EPphysics.ao-ph

A Terrestrial Gamma-ray Flash with an Asymmetric Footprint Observed at the Pierre Auger Observatory

The Pierre Auger Collaboration, John Ortberg, David M. Smith, Joseph Dwyer

The Pierre Auger Observatory, a $3000km^2$ detector array that sits 1400m above sea level in Argentina, has the ability to map the entire footprint of Terrestrial Gamma-ray Flashes (TGFs), which are short, intense bursts of gamma rays associated with lightning. This is in contrast to the vast majority of TGF detections that only occur in a single detector in space. In this paper we leverage this capability to perform two important analyses on an event from 2007, chosen for its large footprint an…

Read →
nucl-thastro-ph.HEcond-mat.quant-gashep-ph

Strongly coupled quark matter in neutron stars and their mergers

Konstantin Maslov, Ralf Rapp, Joaquin Grefa, Veronica Dexheimer, Claudia Ratti

The discovery of the strongly-coupled quark-gluon plasma (sQGP) in high-energy heavy-ion collisions has revealed remarkable properties of matter at high temperature, with transport coefficients close to conjectured bounds from quantum field theory at strong coupling. The high sQGP collision rates imply very large energy uncertainties and the melting of quasiparticle structures. Deploying quantum many-body theory based on the self-consistent $T$-matrix approach for the sQGP at high temperature, w…

Read →
astro-ph.SR

Statistical Energy Budget of the Solar Wind with Parker Solar Probe and Solar Orbiter : 1 - Unbalanced Total Energy Radial Evolution

Jean-Baptiste Dakeyo, Pascal Démoulin, Victor Réville, Stuart Bale, Tamar Ervin, Milan Maksimovic, Olga Alexandrova, Mingzhe Liu et al.

The magneto-hydrodynamic (MHD) description of the solar wind has long been regarded as one of the most successful frameworks for investigating solar wind heating and acceleration. Under a set of simplifying assumptions, it provides a reduced large-scale description that is widely used to study the energetic role of electromagnetic fluctuations in the solar wind energy budget. In practice, applying simplification to MHD can result in the loss of some physics compared to an exact set of equations.…

Read →
astro-ph.IM

96 kHz on-sky imaging on an adaptive optics system with a single-photon avalanche diode

Theodore A. Grosson, Maaike A. M. van Kooten, Kathryn Jackson, Jean-Pierre Veran, Simon Carrier

Astronomical observations requiring extremely high angular resolution necessitate advanced adaptive optics (AO) systems to overcome blurring caused by the atmosphere. In addition to obtaining much sharper point-spread functions (PSFs) with these systems, it is beneficial to be able to characterize the behaviour of the resulting PSF across time and wavelength. We have installed a commercially-available Single-photon avalanche diode (SPAD) array on the focal plane of the REVOLT AO testbench at the…

Read →
astro-ph.IMastro-ph.GA

Exploring the trade-space of distributed aperture telescopes for faint-object spectroscopy

Theodore A. Grosson, Deborah M. Lokhorst, Alan W. McConnachie

Scientific programs targeting the faintest objects push modern telescopes to increasingly large sizes, high costs and complex designs. Obtaining spectra of low surface brightness galaxies, for example, requires hours of observations on state-of-the art instruments. Increasing telescope diameters beyond 40 m raises potentially insurmountable challenges for design and funding. An innovative strategy for combating these costs is to use many small telescopes in place of a single large aperture. For…

Read →
astro-ph.SR

The Hot, Continuum-compact State of the Yellow Hypergiant V509 Cassiopeiae: CHARA Diameters, CO-band Angular-extension Constraints, and Companion Limits

Narsireddy Anugu, Gail H. Schaefer, Douglas R. Gies, Anni Kasikov, John D. Monnier, Stefan Kraus, Karolina Kubiak

Yellow hypergiants are rare, evolved massive stars generally interpreted as post-red-supergiant objects evolving blueward through or near the dynamically unstable Yellow Evolutionary Void. V509~Cassiopeiae is a remarkable example: its spectroscopically inferred effective temperature increased from approximately 5000~K in the mid-1980s to about 7900~K by the late 1990s and has since remained near this value during its post-heating state. We use simultaneous six-telescope CHARA observations obtain…

Read →
q-bio.OTastro-ph.EPastro-ph.IM

Geochemical Hazard Assessment of Martian Regolith for Future Human Exploration

Mavia Anjum, Gwendolyn D. Bart

As human missions to Mars move from concept to planning to reality, a systematic quantitative health risk assessment of martian regolith exposure has become critically important. This study presents a comprehensive multi-element, multi-pathway health hazard analysis of martian regolith for a 70 kg adult astronaut on an 18-month surface mission, using bulk silicate Mars geochemical data and Earth Upper Continental Crust reference values as baseline comparators. We computed Average Daily Dose, Haz…

Read →
astro-ph.IM

X-ray grating spectroscopy as a mission enhancement

Hans Moritz Guenther, Ehud Behar, Joel N. Bregman, Laura W. Brenneman, Alexander R. Bruccoleri, Lía Corrales, Elisa Costantini, Thomas Dauser et al.

We propose to add instruments to any potential future X-ray mission with focussing optics that is considered in NASA's ASTRA framework. Such an instrument is a necessity to study AGN wind outflows and feedback, find the missing baryons, study the intergalactic medium, and analyze abundances and chemical bonds in dust grains throughout the Milky Way. We conclude that those science goals can be achieved with a spectral resolving power > 3000 in the soft X-ray band (about 10-40 Ang) and an effectiv…

Read →
astro-ph.EP

Probing the Taxonomic Diversity of the Small Near-Earth Object Population

Andy J. López-Oquendo, David E. Trilling, Michael Mommert, Michaël Marsset

Small near-Earth objects (NEOs) represent the immediate source population of meteors and meteorites and provide a direct window into the compositional and dynamical evolution of the inner Solar System. However, their small sizes, rapid rotation rates, and short observability windows have historically limited systematic compositional characterization. We present results from a multi-year rapid-response near-infrared spectrophotometric survey of recently discovered NEOs conducted with the UKIRT-WF…

Read →
astro-ph.GA

Radio-dust connection in quasars driven by powerful ionised outflows

V. A. Fawcett, C. M. Harrison, T. Costa2, D. M. Alexander, C. Andonie, H. Haidar, R. D. Shepherd, C. L. Sargent et al.

Feedback from dusty quasars is thought to be a key driver in galaxy evolution. Multiple studies have reported a link between dust extinction and radio emission in quasars, possibly attributed to winds or jets interacting with the interstellar medium. We use optical spectra from the Dark Energy Spectroscopic Instrument (DESI) to test whether ionised outflows could be driving the observed radio-dust connection and to determine whether dust and/or colour play a role in producing high-velocity ionis…

Read →
astro-ph.GA

Radio-dust connection in quasars driven by powerful ionised outflows

V. A. Fawcett, C. M. Harrison, T. Costa, D. M. Alexander, C. Andonie, H. Haidar, R. D. Shepherd, C. L. Sargent et al.

Feedback from dusty quasars is thought to be a key driver in galaxy evolution. Multiple studies have reported a link between dust extinction and radio emission in quasars, possibly attributed to winds or jets interacting with the interstellar medium. We use optical spectra from the Dark Energy Spectroscopic Instrument (DESI) to test whether ionised outflows could be driving the observed radio-dust connection and to determine whether dust and/or colour play a role in producing high-velocity ionis…

Read →
astro-ph.HEastro-ph.GAhep-ph

Decisive evidence for a global cosmic-ray feature in gamma-ray data

Fernando Valenciano, Pedro De la Torre Luque, Daniele Gaggero, Jorge Martin Camalich

We analyze 17 years of Fermi-LAT data to study the diffuse $γ$-ray emission along the Galactic plane and its connection to cosmic-ray (CR) propagation. Accounting for correlated instrumental systematics, we find decisive evidence for a spectral break at $\sim20-30$ GeV, present across the inner Galactic disk, with a preference of $Δχ^2=39.78$ ($4.44 σ$ global). The energy and amplitude of this feature are in striking agreement with the spectral feature observed in local CR nuclei, indicating tha…

Read →
physics.flu-dynastro-ph.EPastro-ph.SR

Internal heating in rapidly rotating convection is not a shortcut to geostrophic turbulence

Justin A. Nicoski, Tobias G. Oliver, Stefano Maffei, Michael A. Calkins

Convective turbulence in planets and stars is often driven by internal heating. This forcing mechanism has also been proposed as a means of accessing the diffusion-free scalings of the geostrophic turbulence (GT) regime at modest forcing. We test this with the asymptotically reduced quasi-geostrophic model, which is formally valid in the limit of vanishing Ekman number, $Ek \rightarrow 0$, and retains the Prandtl number as an independent parameter. We find no such shortcut: the Nusselt and Reyno…

Read →
astro-ph.IMastro-ph.COastro-ph.GAastro-ph.HE

Lynx2030 Science Analysis Group: Final Report

Lynx2030 Science Analysis Group, Simon R. Bandler, Laura W. Brenneman, Nico Cappelluti, Daniel Castro, Steven R. Ehlert, W. Peter Maksym, Fabio Pacucci et al.

The Lynx2030 Science Analysis Group (SAG) was convened to reassess the scientific goals and technical drivers of the Lynx mission concept amid a rapidly evolving astrophysics landscape. Building on the original Lynx Concept Study, the SAG examined how recent discoveries, emerging facilities, and advances in instrumentation influence the scientific opportunities for a next-generation flagship X-ray observatory. Through focused working groups, the SAG investigated the scientific impact of enhanced…

Read →
astro-ph.EPastro-ph.IM

Impacts of Correlated Noise on Retrievals of Exo-Earth Atmospheres

Nicole Wolff, Bruce Macintosh, Tyler D. Robinson, Sarah Blunt, Jean-Baptiste Ruffio, Beck Dacus, Alex Madurowicz, Marshall Perrin et al.

The Habitable Worlds Observatory (HWO) aims to accomplish high-contrast imaging and spectroscopy of true Earth analogs for the first time. However, high-contrast spectroscopy with HWO may be limited by residual speckles which persist after deformable mirror correction and post-processing, hindering atmospheric characterization. Previous studies of self-luminous giant planets showed that neglecting spectrally correlated errors due to speckles results in biased inferences of planetary parameters.…

Read →
astro-ph.EPastro-ph.IM

On the Impact of Correlated Noise and Spectral Resolution on the Retrieval Analysis of the Habitable World Observatory

Ji Wang, Philipp A. Huber, Sascha P. Quanz

Finding signs of life elsewhere in the universe is the holy grail of the field of exoplanets. Future space missions such as the Habitable World Observatory (HWO) are under development to search for biosignatures in exoplanets. We investigate the impact of correlated noise and spectral resolution on the retrieved biosignature chemical abundances. At the nominal spectral resolving power R=140 for HWO, we show that in 40\% of the simulated runs the retrieved biosignature (H$_2$O and O$_2$) abundanc…

Read →
astro-ph.GA

Shock-heated Away: The Impact of Radiative Cooling on Gas-Phase Transitions in Supernova Remnants

Zuzanna Kocjan, Benedikt Diemer, Vadim A. Semenov, Shmuel Bialy, Uri Malamud

Supernova (SN) feedback plays a central role in regulating the structure of the interstellar medium (ISM) through the injection of energy and momentum. The amount of hot gas produced by a supernova is a key quantity that determines how efficiently SN feedback heats the ISM and drives mass exchange between its different gas phases, here defined as cold ($T 2\times10^4\, \mathrm{K}$) gas. However, previous studies have reported discrepant amounts of hot gas formed under otherwise similar ambient c…

Read →
gr-qcastro-ph.HEhep-th

A Unified Treatment of the Self-Force Problem

Beka Modrekiladze, Ira Z. Rothstein, Jordan Wilson-Gerow

This paper introduces formalism, based on worldline effective field theory, which allows one to systematically calculate the gravitational self-force on a compact object immersed in an environment with non-vanishing stress energy. Using the closed time path integral we present a universal effective action that can be used to calculate the equations of motion of a compact object due to its interaction with the environment to any order in the relevant expansion parameters, the relative importance…

Read →
astro-ph.HEastro-ph.IM

Galactic Science with Ultra-High Angular Resolution X-ray Imaging

Paul A. Draghis, Jeremy Hare, Mayura Balakrishnan, Poshak Gandhi, Tyler Holland-Ashford, Margarita Karovska, Thomas Maccarone, Herman L. Marshall et al.

Milli- to micro-arcsecond X-ray imaging will open a new observational regime for Galactic astrophysics by resolving physical scales that are inaccessible to current X-ray observatories. This white paper highlights the science enabled by such capabilities across four broad questions: how particles are accelerated, how stars die, how accretion is fueled, and what populations of X-ray sources inhabit the Galaxy. Ultra-high angular resolution will enable many new studies, such as resolving shocks an…

Read →
astro-ph.GAastro-ph.CO

Super-Eddington Little Blue Dots May Reionize Helium Too Early

Christopher Cain, Brent Smith, Gibson B. Bowling, Yongda Zhu, Lily Whitler, Rafael Ortiz, Anson D'Aloisio, Rogier Windhorst et al.

The James Webb Space Telescope (JWST) has identified an abundant population of faint Active Galactic Nuclei (AGN) at $z \gtrsim 4$ which display broad emission lines, compact morphologies, and blue ultraviolet--optical continua. These ``Little Blue Dots' (LBDs) have been suggested to belong to the same family of objects as the more controversial ``Little Red Dots' (LRDs), with differences between the two largely owing to viewing angle effects. In this scenario, super-Eddington accretion resultin…

Read →
astro-ph.GA

The GECKOS survey: Assembly history of the lenticular galaxy NGC 3957

Yuchen Ding, Marie Martig, Ling Zhu, Amelia Fraser-McKelvie, Ryan Leaman, Glenn van de Ven, Jesse van de Sande, Francesca Pinna et al.

We analyse the assembly history of the edge-on lenticular galaxy NGC 3957 using deep integral-field spectroscopic MUSE data from the GECKOS survey. By applying a dust-corrected Multi-Gaussian Expansion and a population-orbit superposition model, we disentangle the galaxy's stellar kinematics, age, and metallicity. We dynamically decompose the galaxy and identify three distinct components: a dynamically-cold main disc, a compact Nuclear Stellar Disc (NSD), and a hot component. The NSD emerges as…

Read →
astro-ph.COastro-ph.GAastro-ph.HEhep-exhep-ph

AXIS Could Have Accessed Dark Matter Decays

Joshua W. Foster, Inci Karaaslan, Gordan Krnjaic, Nimrod Shapir

The Advanced X-ray Imaging Satellite (AXIS) was a mission concept designed to improve upon the sensitivity and spatial resolution of the Chandra X-ray Observatory and XMM-Newton. Although AXIS was not selected for implementation, the concept study defined a mature instrument design with low-background, arcsecond imaging over the $0.3$-$10$ keV energy range, a large effective area, and a wide field of view. These capabilities provide a useful benchmark for the dark matter decay sensitivity of fut…

Read →
astro-ph.GAastro-ph.IM

Spatially-Resolved Spectra of Diffuse Galactic Light using 10.8 M DESI Sky Fibers

Andrew K. Saydjari, Bruce T. Draine, Timothy D. Brandt, Edward F. Schlafly, Arjun Dey, Douglas P. Finkbeiner, J. Aguilar, S. Ahlen et al.

Using 10.8 million ``blank'' sky spectra from the DESI Year 3 dataset, we measure the diffuse galactic light (DGL) spectrum in the optical at spectral resolution $R \sim 4000$ by correlating with far-infrared emission from IRAS. Subdividing the sky into 54 deg$^2$ pixels (HEALPix, NSIDE = 8), we map the variation of the DGL correlation spectrum and nebular emission lines across the DESI footprint in the high-Galactic-latitude sky. The increased data volume over previous SDSS-based analyses enabl…

Read →
astro-ph.GA

Magnetic destabilisation in disc galaxies: Filament/feather formation

Raghav Arora, Oscar Agertz, Christoph Federrath, Mark R. Krumholz

Gas gravitational instability plays a crucial role in secular galactic evolution, but the role played by magnetic fields in mediating this instability - despite their dynamical relevance and ubiquity - is still not understood. To investigate this question we conduct a parameter study using numerical simulations of 3D isolated disc galaxies that are initialized in equilibrium, but have a range of initial magnetisation, quantified by $β\in \{0.1, 0.5, 1, 10, 100, \infty\}$, where $β$ is the ratio…

Read →
astro-ph.HE

A Similarity Theorem and Its Breakdown in Atomic Black Hole Accretion

Marcus DuPont

Atomic gas in a point-mass potential possesses an exact similarity that survives time dependence, two-body atomic microphysics, and a specified class of radiation and feedback laws. At fixed ambient temperature and composition, $M_\bullet\mapstoλM_\bullet$ and $n_\infty\mapstoλ^{-1}n_\infty$ enlarge radii and times by $λ$ while preserving dimensionless profiles, optical depths, Eddington ratios, and variability. Here $M_\bullet$ is the central mass, $n_\infty$ the ambient number density, and $λ>…

Read →