UchUchU

Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.IMeess.SYphysics.ins-det

Calibration electronics for the 30 and 40 GHz instrument (TFGI) of the QUIJOTE experiment

Jorge Luis Díaz-Acosta, Roger John Hoyland, Francisco Javier Casas, Enrique Martinez-González

The 30 and 40 GHz instruments of the QUIJOTE radio astronomy experiment use very sensitive receivers which need to be characterized both to ensure their proper functioning and for their calibration. Given the age of the PXI-1031DC device used up until now for this purpose, the design of a new device, the Calibrator TFGI QUIJOTE, has been proposed. This new device has been designed with the idea of being simple and modular, easy to use and upgrade. It is built on a Raspberry Pi 5 system, using an…

Read →
astro-ph.EP

The Birth of Minor-Body Populations in the $β$ Pictoris System I: The First 25 Myr

S. Torres, J. L. Gragera-Más, A. J. Mustill, E. Villaver

The discovery of the third known giant planet, $β$ Pic d, offers a new opportunity to investigate how planet-disk interactions build the minor-body architecture of the young Beta Pictoris system. We study the formation and redistribution of scattered-disk objects, falling evaporating bodies, a proto-Oort-cloud population, transitional interstellar objects, and interstellar objects. Using $N$-body simulations, we evolve a primordial planetesimal disk extending from 0.5 to 1000 au for 25 Myr under…

Read →
gr-qcastro-ph.HE

Non-Conservative Mechanics in the Compact-Body Mass-Shell Model and its Waveform Structuring

Noah M. MacKay

A novel reinterpretation on the effective one-body (EOB) mapping of compact-body binary (CBB) coalescence was previously considered. Instead of the conventional ``marble in a funnel" description of EOB, CBB coalescence is modeled as the concurrent rotation and contraction of a hollow shell with a constant reduced mass measure. Merger is achieved, therefore, when the shell radius reaches the total mass radius. While past works analyzed the energetics sector of the model and the radiated gravitati…

Read →
astro-ph.HEphysics.plasm-ph

Energy Partition in Relativistic Electron-Positron-Ion Reconnection

Nilay Mancini, Luca Comisso, Lorenzo Sironi

Relativistic magnetic reconnection, a prime mechanism for particle acceleration, has been extensively studied in electron--ion and pair plasmas, but how the dissipated energy is shared among species in electron--positron--ion plasmas, and in particular how ions are energized within a pair-dominated layer, remains poorly understood. We develop an analytic theory that couples single-particle orbit dynamics to the collective plasma response, and we validate it with particle-in-cell simulations span…

Read →
astro-ph.HEastro-ph.IM

The Auger Radio Infill SKALA Extension (ARISE): First Air-Shower Measurements

Carmen Merx for the Pierre Auger Collaboration

The Auger Radio Infill SKALA Extension (ARISE) was installed at the Pierre Auger Observatory in 2025 to detect the radio emission in the band of $50-350\,$MHz of near-vertical cosmic-ray air showers of energies around and above $100\,$PeV. The array comprises 18 SKALA~v2 antennas deployed around one of the surface-detector stations of the $433\,$m array (SD-433), which provides the trigger for ARISE. We present first measurements with ARISE and show the detection of radio pulses associated with…

Read →
astro-ph.SR

Tidal Dissipation from Circularization in Kepler Binaries

Joshua Schussler, Torsha Majumder, Kaloyan Penev

Understanding tidal dissipation is a requisite step for explaining the evolution of systems such as short-period binaries. This understanding has not yet been achieved, and in fact there are many different approaches to modelling tides. By using Bayesian analysis on a system-by-system basis, we provide additional constraints on dissipation for 105 short-period Sun-like Kepler binaries. We account for period-dependent $Q$ and stellar evolution, and propagate observational uncertainties to uncerta…

Read →
astro-ph.HE

A mechanism for fast radio bursts and their narrow spectra

Andrei M. Beloborodov, Ivan Demidov

We find an emission mechanism for fast radio bursts (FRBs) capable of producing broad and narrow spectra. It operates in magnetar explosions, which launch an electromagnetic pulse from the inner magnetosphere at radii $r_0\sim 10^{7}$ cm. Plasma inside the pulse accelerates outward with Lorentz factor $Γ(r)\approx r/r_0$. Before exiting the magnetosphere at radius $r\sim 10^{10}$ cm, the pulse passes through ambient kHz waves that populate the magnetospheres of active magnetars. We show that the…

Read →
astro-ph.IM

Flux Density Calibration of Radio Bursts Detected in the Sidelobes of the Canadian Hydrogen Intensity Mapping Experiment

Fengqiu Adam Dong, Meena Seth, Paul Scholz, Nina V. Gusinskaia, Kiyoshi W. Masui, Juan Mena-Parra, Daniele Michilli, Ari Polterovich et al.

The Canadian Hydrogen Intensity Mapping Experiment/Fast Radio Burst (CHIME/FRB) instrument is a transient astrophysical burst survey that is discovering FRBs, pulsars, and long-period transients. As a transit telescope, the survey is most sensitive within 2 degrees of the meridian; however, CHIME/FRB can detect bright astrophysical bursts out to its horizon, at 10^-2 to 10^-3 of its peak sensitivity. In this study, we detail the flux density calibration procedure for these bursts detected in the…

Read →
astro-ph.GA

ALMA Chemical Evolution (ACE) Survey: Molecular gas properties of low-mass, low-metallicity galaxies at cosmic noon

Gergő Popping, Ivanna Langan, Nikki N. Geesink, Melanie Kaasinen, Irene Shivaei, Leindert A. Boogaard, Daizhong Liu, Max Parente et al.

Molecular gas plays a central role in regulating star formation and galaxy evolution, yet observational constraints at cosmic noon remain biased toward massive, metal-rich systems. We present ALMA Band 3 observations of the CO J=3-2 transition in 26 unlensed star-forming galaxies from the ALMA Chemical Evolution (ACE) Large Program at z~2-2.5, probing stellar masses of $10^{9} < M_\star < 10^{10.5}\,\mathrm{M}_{\odot}$ and sub-solar metallicities (8.2 < 12 + log(O/H) < 8.6). We derived molecular…

Read →
astro-ph.GA

ALMA Chemical Evolution (ACE) survey: the dust content of subsolar metallicity galaxies at cosmic noon

M. Solimano, I. Shivaei, G. Popping, L. A. Boogaard, I. Langan, R. Popescu, N. N. Geesink, A. Pope et al.

Dust plays a key role in galaxy evolution by influencing star formation and shaping the observed spectrum of galaxies. However, at z~2 (cosmic noon) our knowledge of the dust mass budget is currently limited to the most massive, metal-rich systems, which are not representative of the bulk galaxy population. Here, we probe the lower mass, subsolar metallicity regime by measuring the dust mass of 25 galaxies at z~2.3 from the ALMA Chemical Evolution (ACE) Large Program. The sample contains star-fo…

Read →
astro-ph.HEastro-ph.COgr-qchep-ph

Self-Similar Mass Spectra of Hierarchical Black Hole Mergers

Liam Blum, Stefano Profumo, Ryan Schantz, Quoc Ha Tran

Black holes that merge repeatedly carry a record of that history in their mass distribution. We treat hierarchical merging as a coagulation problem, in which a single kernel encodes how the merger rate depends on the masses involved and on cosmic time, and we derive the late-time spectra that such populations approach. The framework yields closed scaling laws, an exactly solvable benchmark, and a classification of merger environments by a single exponent measuring how strongly mergers favor or s…

Read →
astro-ph.EPastro-ph.GAastro-ph.SRhep-ph

The Galactic Dynamics of Free-Floating Planets: From Ejection Kicks to Microlensing

Zara Sayed, Stefano Profumo, Nolan Smyth

Free-floating planets (FFPs) may retain dynamical signatures of the mechanisms that eject them from their host systems. We integrate $10^6$ collisionless FFP test particles for $10^8$~yr in a static, phenomenological Galactic potential, comparing a mass-independent kick model with a mass-coupled prescription ($σ_{\rm CB}\propto M^{-0.15}$, $v_{\rm PL}\propto M^{-0.5}$) against a matched no-kick control. The imposed mass dependence is recovered at injection, with the combined-channel median coupl…

Read →
astro-ph.GA

What Drives Galaxy-Galaxy Differences In The Selective Attenuation Curve? New Perspectives from DESI DR1

Andrew Mizener, Daniela Calzetti, Ranga-Ram Chary, John Moustakas

Leveraging a sample of 3457 galaxies drawn from DESI DR1 and cross-matched with archival GALEX UV photometry, we construct new dust attenuation curves and measure how the shape of these curves vary as a function of galaxy properties. Our curves are built by comparing the median flux densities of galaxies that have been divided into bins of nebular opacity, measured via the Balmer optical depth (i.e. the H$α$/H$β$ ratio). When no further cuts on galaxy properties are applied, we find an attenuati…

Read →
astro-ph.EP

A fifth companion in the HR 8799 system revealed by Gaia

A. -M. Lagrange, K. Gozdziewski, F. Kiefer, H. Beust, P. Rubini, A. Zurlo, P. Thebault, A. Boccaletti et al.

HR 8799 is the benchmark young multi-planet system, hosting four directly imaged giant planets orbiting between a warm inner belt and a cold outer debris ring. However, the few-au region has remained observationally inaccessible, lying beyond the reach of conventional high-contrast imaging and challenging for radial-velocity techniques due to stellar pulsations. Here we combine Gaia absolute astrometry and Hipparcos-Gaia proper-motion anomalies with radial velocities and high-contrast imaging to…

Read →
astro-ph.GA

Sown at Cosmic Dawn: Searching for Pop III Signatures in JWST JADES He II Selected Line Emitters

Rosa Roberts, Giorgia Riley, Christopher J. Conselice, Duncan Austin, Thomas Harvey, Lewi Westcott, Jordan C. J. D'Silva

Population III (Pop III) stars, the first generation of metal-free stars, remain undetected, partly because entirely pristine galaxies represent a short-lived phase. We instead target the longer-lived self-polluted and hybrid Pop III-Pop II phases, in which surviving metal-free Pop III stars coexist with enriched gas and newly formed Pop II stars, producing strong He II alongside detectable UV metal lines. We search for this signature in 84 strong He II-emitting galaxies at z = 3-7 in the JWST/J…

Read →
astro-ph.GA

Euclid Quick Data Release (Q1) Euclid spectroscopy of quasars. 2. Physical properties from spectral fitting

Euclid Collaboration, J. Calhau, G. Calderone, A. Feltre, M. Scialpi, V. Allevato, H. Landt, F. Ricci et al.

A substantial volume of spectroscopic data has become available with the Euclid Data Release (Q1), which represents a unique opportunity to study quasars (QSOs) in the Euclid Deep Fields, provide spectroscopic measurements, and estimates of their physical properties. We present results from a spectroscopic analysis of QSOs with HE < = 22.5 using Q1. We use external catalogues from surveys such as the Dark Energy Spectroscopic Instrument (DESI), Gaia, Wide-field Infrared Survey Explorer (WISE), a…

Read →
astro-ph.HEastro-ph.COhep-ph

Systematic Uncertainties and Their Impact on Gamma-Ray Searches for Dark Matter in Dwarf Galaxies

Toni Bertólez-Martínez, Dan Hooper, Arifa Khatee Zathul

Gamma-ray observations of Milky Way dwarf galaxies provide some of the strongest constraints on dark matter annihilation and are approaching the sensitivity required to test dark matter interpretations of the Galactic Center Gamma-Ray Excess. The results, however, depend critically on the inferred dark matter distributions in these systems, conventionally described by their $J$-factors and spatial profiles. We review several sources of systematic uncertainty in dwarf galaxy $J$-factor determinat…

Read →
astro-ph.SRastro-ph.GAastro-ph.IM

White Dwarf Natal Kicks as Velocity-Space Random Walks. II. Binary Stellar Evolution and Observational Kick Constraints

Dang Pham, Stephen Majeski, Taeho Ryu, Gabriel Tomassini, Andrea Chiavassa

Wide binaries containing white dwarfs (WDs) provide a pathway to exploring post-main-sequence (MS) natal kicks associated with asymmetric mass loss. In this work, we develop a binary population synthesis model that involves episodic mass loss and velocity kicks during the thermally-pulsing asymptotic-giant-branch (TP-AGB) phase of stellar evolution, when mass loss is expected to be most significant. We compare our synthesized populations against the Gaia DR2 and DR3 data for wide WD-MS and WD-WD…

Read →
astro-ph.SRastro-ph.EPastro-ph.GA

White Dwarf Natal Kicks as Velocity-Space Random Walks. I. Fokker-Planck Theory

Stephen Majeski, Dang Pham, Taeho Ryu, Gabriel Tomassini, Andrea Chiavassa

White dwarfs are the most common end state of stellar evolution, including that of our own Sun, making their formation critical to completing a more comprehensive understanding of stellar evolution and even determining the eventual fate of the solar system. Wide binaries containing white dwarfs offer a powerful probe: their components evolve largely independently, yet stellar mass loss and velocity impulses (natal kicks) on the white dwarf progenitor leave measurable imprints on orbital properti…

Read →
astro-ph.SRastro-ph.EPastro-ph.GA

White Dwarf Natal Kicks as Velocity-Space Random Walks. I. Fokker-Planck Theory

Stephen Majeski, Dang Pham, Taeho Ryu, Gabriel Tomassini, Andrea Chiavassa

White dwarfs are the most common end state of stellar evolution, including that of our own Sun, making their formation critical to completing a more comprehensive understanding of stellar evolution and even determining the eventual fate of the solar system. Wide binaries containing white dwarfs offer a powerful probe: their components evolve largely independently, yet stellar mass loss and velocity impulses (natal kicks) on the white dwarf progenitor leave measurable imprints on orbital properti…

Read →
astro-ph.GAastro-ph.CO

Cosmic web Ly$α$ emission in a sample of overdense regions

Davide Tornotti, Michele Fumagalli, Matteo Fossati, Roland Bacon, Fabrizio Arrigoni Battaia, Rajeshwari Dutta, Michele Fulghieri, Celine Peroux et al.

We present a complete and homogeneous analysis of the Ly$α$ emission properties of the cosmic web at $3 \lesssim z \lesssim 5$ as a function of the overdensity of Ly$α$ emitters (LAEs) in the MUSE Ultra Deep Field (MUDF) and the MUSE Extremely Deep Field (MXDF). We identify 41 overdensities, probing environments that are $δ\approx 2 - 10$ times denser than the field. We search for extended emission down to surface brightness (SB) levels of $3 - 5 \times 10^{-20}\ \mathrm{erg\ s^{-1}\ cm^{-2}\ ar…

Read →
astro-ph.GAastro-ph.IM

An Archival Calibration of JWST/MIRI Prism Wide-Field Slitless Spectroscopy: Methodology, Performance, and a Mid-Infrared Spectral Atlas of Galaxies at $z=0-4$ in the GOODS-N/S Fields

Fengwu Sun, Javier Álvarez-Márquez, Eiichi Egami, Román Fernández Aranda, Jakob M. Helton, Xiaojing Lin, Jianwei Lyu

Through the Low Resolution Spectroscopy (LRS) observing mode of JWST/MIRI, the P750L prism disperses the entire ~70"$\times$110" imager field, turning MIRI into a wide-field slitless spectrograph (WFSS) at 5-14 $μ$m with spectral resolution $R\sim100$. Using archival MIRI LRS data taken in the GOODS-N/S deep fields and calibration programs, we present a complete and precise calibration suite for MIRI WFSS through an AI-assisted agentic workflow under human supervision. The calibration includes f…

Read →
astro-ph.GA

Quiescent Galaxies at $z > 2$ from CAPERS spectroscopy and their Number densities

Lu Shen, Weida Hu, Casey Papovich, Justin Cole, Mark Dickinson, Pablo Arrabal Haro, Anthony J. Taylor, Adam C. Carnall et al.

Recent JWST observations have revealed an overabundance of quiescent galaxies at high redshift. Photometric methods, such as photometry-derived sSFRs, $UVJ$ colors, and synthetic $ugi_s$ colors, are commonly used to identify quiescent galaxies, but their completeness and purity remain poorly constrained. Here we present a spectroscopically selected sample of 19 quiescent galaxies at $2 \leq z \leq 4$ from the CANDELS-Area Prism Epoch of Reionization Survey (CAPERS). They are selected with $M_\as…

Read →
astro-ph.SR

Cause of chromospheric opposite polarity intrusions discovered in Sunrise III/SCIP data: MURaM-ChE simulations point to twisted flux ropes

Patrick A. Ondratschek, Damien F. Przybylski, Robert H. Cameron, H. N. Smitha, Sami K. Solanki, Masahito Kubo, Andreas Lagg, Achim Gandorfer et al.

The Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) instrument onboard the balloon-borne Sunrise III observatory provided new high-resolution observations of the solar chromosphere in the Ca II 854.2 nm line. The Stokes-V signal in magnetic network regions was found to show fine-structured details, which suggests the magnetic field above the network elements does not simply expand as a unipolar feature but displays opposite-polarity-intrusions (OPIs). These features appear as elongated…

Read →
astro-ph.GAastro-ph.SR

The Galactic Phosphorus Survey. I. Chemical Evolution across the Galactic Disk from $\sim$750 FGK Stars

Dionysios Gakis, Keith Hawkins, Zachary G. Maas, Christopher Sneden, Melike Afşar, Natalie R. Hinkel, Chenguang Sun, Wenwei Liang et al.

Phosphorus (P) is an odd-$Z$ element produced primarily in massive stars and is also important for planetary chemistry as an element essential to life. However, its evolution over cosmic time remains poorly constrained because precise and homogeneous stellar P measurements are scarce. We determine the relationship between [P/Fe] and [Fe/H] over a range of metallicities across the Galactic disk and assess its variation between different stellar populations using the largest uniformly analyzed sam…

Read →
astro-ph.GA

From IFS Maps to 3D Structure I: Constraining Geometry in the Circumgalactic Medium

Mandy C. Chen, Michael Rauch, Zhijie Qu, Gwen C. Rudie, Hsiao-Wen Chen, James R. Beattie

The three-dimensional geometric structure of the cool (T~$10^4$ K) circumgalactic medium (CGM) -- the line-of-sight depth and the number of discrete clumps -- is poorly constrained. Existing inferences come predominantly from quasar absorption-line statistics, but these pencil-beam probes provide limited spatial and kinematic information. Here we show that spatially resolved emission-line maps from integral field spectrograph (IFS) observations provide complementary, novel constraints on cool CG…

Read →
astro-ph.SRastro-ph.GA

The Treasury of Extremely Metal-Poor O Stars

O. Grace Telford, Christiana Erba, Kristen B. W. McQuinn, Calum Hawcroft, Andreas A. C. Sander, Julia Roman-Duval, John Chisholm, Danielle A. Berg et al.

The Treasury of Extremely Metal-Poor O Stars (TEMPOS) is a Hubble Space Telescope survey of hot and massive O-type stars in nearby, low-metallicity galaxies ($\lesssim$20% of the solar metallicity, $Z_\odot$). Understanding massive-star physics in this regime is essential to interpret observations of metal-poor galaxies, including both low-mass dwarf galaxies and chemically unevolved galaxies in the early Universe. Yet, few far-ultraviolet (FUV) spectra of O stars of sufficient quality to charac…

Read →
astro-ph.GA

ALMA Chemical Evolution (ACE) survey: dust-to-gas ratios in sub-solar metallicity galaxies at cosmic noon

N. N. Geesink, G. Popping, L. A. Boogaard, I. Langan, A. Pope, R. Popescu, I. Shivaei, M. Solimano et al.

Dust is a fundamental component of the interstellar medium and provides a key tracer of the baryon cycle that regulates galaxy evolution. The dust-to-gas ratio links metals in the gas phase to those locked into dust grains, making it a sensitive diagnostic of dust production, grain growth, and destruction. We present measurements of the dust-to-molecular-gas ratio ($\rm DGR_{mol}$), for typical star-forming galaxies ($\log M_\star \approx 10$) at sub-solar metallicites, at $z\simeq2-2.5$ from th…

Read →
astro-ph.EP

Recovering the Morning and Evening Limbs of WASP-94Ab from Its Limb-Averaged JWST Transmission Spectrum

Tyler R. Fairnington, Michael Radica, Michael Zhang, Eliza M. -R. Kempton, Jacob L. Bean, Eva-Maria Ahrer, Arjun B. Savel, Pascal S. D'Andrea et al.

Recent JWST observations have revealed that the morning and evening limbs of the hot Jupiter WASP-94Ab have very different transmission spectra. An analysis of these resolved limb spectra yielded a metallicity more than an order of magnitude below that obtained from the limb-averaged spectrum, which calls into question the accuracy of traditional retrievals for heterogenous planets. Here we analyze the limb-averaged JWST NIRISS and NIRSpec transmission spectra of WASP-94Ab using both a standard…

Read →
astro-ph.GA

ALMA Chemical Evolution (ACE) survey: The gas fundamental metallicity relation at cosmic noon

I. Langan, I. Shivaei, G. Popping, L. A. Boogaard, N. N. Geesink, M. Kaasinen, A. Pope, R. Popescu et al.

Chemical enrichment shapes how galaxies form and evolve. The gas-phase metallicity is directly linked to the stellar mass, star formation rate, and cold gas of the interstellar medium. Thus, the cold gas fundamental metallicity relation (GFMR) is a powerful tool for probing galaxy evolution, bridging large-scale gas flows modulating the cold gas reservoir and small-scale metal enrichment tracing the cumulative impact of star formation. Constraining all these properties for the same representativ…

Read →