UchUchU

Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GAastro-ph.HE

The ALMA carbon monoxide supernova (ACOS) survey II. Turbulent giant molecular clouds at the positions of core-collapse supernovae

M. Solar, M. J. Michałowski, J. Nadolny, J. Sollerman, E. Zapartas, A. Oliva, L. Galbany, J. Hjorth et al.

Context. Study of cold molecular hydrogen gas (hereafter molecular gas) provides crucial insights into its interplay with star-forming regions. However, the connection between molecular gas turbulence and the sites of massive star ($> 8~\rm{M}_{\odot}$) explosions as core-collapse supernovae (CCSNe) remains unexplored. Aims. We measure for the first time the turbulence of molecular gas in environments of CCSNe, with the aim to constrain the nature of their progenitors. Methods. In order to reach…

Read →
astro-ph.GA

GATOS: Distinct Feedback Modes in AGN Central Regions Revealed by Spatially Resolved JWST Spectroscopy

Lulu Zhang, Chris Packham, Erin K. S. Hicks, Ismael García-Bernete, Almudena Alonso-Herrero, Ric I. Davies, Martin J. Ward, Daniel E. Delaney et al.

This manuscript presents JWST MIRI/MRS observations of the central $r \approx 40-240$ pc regions of five active galactic nuclei (AGN) spanning a wide range of luminosities (${\rm log}\,L_{\rm bol}/{\rm erg\,s^{-1}} \approx 39.8-43.8$). Combining multiphase diagnostics from polycyclic aromatic hydrocarbons (PAHs), molecular hydrogen (H$_2$), and ionized gas at spatial scales of $\sim 4-24$ pc, this study presents a spatially resolved investigation into the effects of the two distinct AGN feedback…

Read →
physics.plasm-phastro-ph.EPphysics.comp-ph

Dipole-Field Magnetic Windows for Radio-Frequency Transmission Through Hypersonic Plasma Sheaths: A Reduced-Order Scaling Model

Richard Lieu

Hypersonic vehicles and atmospheric-entry bodies can experience radio-frequency communication blackout when shock-heated gas surrounding the vehicle becomes sufficiently ionized that plasma cutoff and collisional attenuation restrict electromagnetic transmission. Magnetic-window approaches attempt to reduce this loss by exploiting the anisotropic dispersion of a magnetized plasma, in which selected right-hand or whistler-like modes may propagate along preferred directions. This paper develops a…

Read →
math.APastro-ph.SRphysics.flu-dyn

On the nonlinear instability of nonrotating Stars

Zhiwu Lin, Xinlin Wu

We study radial nonlinear instability of compactly supported nonrotating equilibria of the three-dimensional Euler--Poisson system with a physical-vacuum boundary. Let $n^u(μ)$ denote the radial instability index furnished by the turning-point theory of Lin and Zeng. Under general structural assumptions on the pressure law, suppose that $n^u(μ)>0$ and that the equilibrium is not a mass extremum, $M'(μ)\neq0$. Conditional on the existence of a sufficiently regular radial solution on the relevant…

Read →
astro-ph.GA

KCWI Discovery of a Spatially Resolved Kpc-Scale Ionized Outflow in NGC 1275

Kylie Yui Dan, Hanae Inami, Thomas Bohn, Sylvain Veilleux, Vivian U, Tianmu Gao, Justin Kader, Rosalie McGurk et al.

We present new Keck Cosmic Web Imager observations of the central few kiloparsecs of NGC 1275, the brightest cluster galaxy of the Perseus Cluster. These integral field spectroscopic data reveal a warm-ionized outflow traced by H$β$ and the [O III] doublet extending out to $\sim2.5$ kpc from the nucleus. The warm-ionized outflow has an [O III]-derived $v_{50}$ of up to $\sim570$ km/s, $w_{80}$ of up to $3780$ km/s, and H$β$-derived outflowing mass of $(2.7 \pm 0.3)\times 10^6$ M$_\odot$. Our H$β…

Read →
astro-ph.IM

Multi-night photometric repeatability of STDWeb: an empirical error budget from a 14-night campaign on a single field

Pierre-Yves Lechapelain

Web-based photometric pipelines such as STDWeb are routinely used by small observatories and professional-amateur networks across the full range of photometric science: variable stars, supernovae, exoplanet transits, transient follow-up. The formal magnitude uncertainty they report describes a single reduction of a single frame; campaign science instead requires the scatter of the same star, same field, night after night. We measure this empirically on the field of the Einstein Probe trigger EP-…

Read →
astro-ph.IM

Design and simulation of a photonic lantern-inspired astrophotonic chip for spectral sensing

Avi Patel, Kevin A. Bundy, Aditya Sengupta, Matthew C. DeMartino, Anna Gagnebin, Emiel Por, Majid Mohammad, Michael Arena et al.

Compact astrophotonic sensors can trade general-purpose spectral coverage for task-specific wavelength discrimination in a small integrated footprint. Developed with the Mazin Lab at UC Santa Barbara, this chip couples a single-mode input into a multimode interference region and seven-port fanout, producing wavelength-dependent output power fingerprints for spectral retrieval. Using ANSYS Lumerical FDTD simulations in silicon nitride, we compare symmetric and staggered-release geometries and qua…

Read →
astro-ph.IM

Design evolution for the Wide-field Spectroscopic Telescope

Will Saunders, Corentin Cudennec, Roland Bacon, Philippe Dierickx, Roelof de Jong, David Lee, Gaston Gausachs

WST is proposed as the next large ESO project to follow ELT, combining Multi-Object Spectroscopy and Integral Field Spectroscopy. Each mode offers order-of-magnitude gains over current systems, and each also presents unprecedented design challenges, both separately and in combination. For large MOS systems, both science performance and spectrograph costs vary steeply with the delivered image quality, so exceptional delivered image quality is paramount. But the 12m aperture and 2 degree field giv…

Read →
astro-ph.GA

The Quasar Feedback Survey: Ionised Outflows in type 2 QSOs with MUSE data

M. Bianchin, C. M. Harrison, T. Costa, V. Mainieri, R. A. Riffel, G. Venturi, D. Kakkad, C. Ramos Almeida et al.

We study ionised gas properties in a sample of 18 luminous (log L$_{\rm bol}\geq45$ erg/s) obscured QSOs at 0.085<z<0.2 observed with VLT/MUSE as part of the multi-wavelength Quasar Feedback Survey (QFeedS) and with VLA at low- and high-resolution data. We compare the outflow-related quantities with values reported in the literature and investigate possible correlations between the outflows and other properties of the ionised gas such as the electron density. We adopt a non-parametric approach t…

Read →
astro-ph.SRastro-ph.HE

From Light to Sound: Spectroscopic Evolution & Sonification of the flaring Nova V612 Scuti

Pragati Acharya, Elias Aydi, Kirill V. Sokolovsky, Brian D. Metzger, Laura Chomiuk, Peter Craig, Luca Izzo, Justin D. Linford et al.

We present photometric and spectroscopic observations of the 2017 Galactic nova V612 Sct, whose optical evolution was marked by multiple unusually large maxima. The eruption included two prominent flares lasting around a month each and reaching amplitudes of about 2.5 mag, followed by a series of smaller flares. Extensive spectroscopic monitoring reveals a striking pattern: with each flare, new absorption systems emerge at progressively higher velocities. This behavior, also seen in other flarin…

Read →
astro-ph.HE

On the Physical Origins of Long Period Radio Transients

Yuanhong Qu, Bing Zhang

Long-period radio transients (LPRTs) are a rapidly growing class of coherent radio sources with periods ranging from minutes to hours, whose central engines and emission mechanisms remain unclear. Motivated by the detection of red dwarf (RD) companions in several LPRTs and by generic period constraints from the Roche limit and the mass transfer limit, we argue that LPRTs naturally separate into two broad classes: shorter-period sources that are likely isolated compact objects and longer-period s…

Read →
astro-ph.GA

Kings of the Milky Way: A Homogeneous Gaia DR3 Analysis of King Open Clusters and the Galactic Disc Metallicity Gradient

Talar Yontan, Selçuk Bilir, Hikmet Çakmak, Olcay Plevne, Esin Soydugan, Seval Taşdemir, Remziye Canbay, Deniz Cennet Çınar et al.

This study aims to establish an internally homogeneous set of structural, astrophysical, and kinematical parameters for King open clusters and to assess their role as tracers of the Galactic thin disc. We present a homogeneous structural, astrophysical, and kinematical analysis of 27 King open clusters using high-precision Gaia DR3 astrometry, photometry, and spectroscopy. Cluster reddenings, distances, metallicities, and ages are determined via a homogeneous Markov Chain Monte Carlo isochrone-f…

Read →
astro-ph.GA

A New Window on the Hα Luminosity Function and Star Formation Rate Density from 1.2 < z < 6.6 from JWST Medium-Band Photometry

Nicholas S. Martis, Chris Willott, Gregor Rihtaršič, Vesna Pirc Jevšenak, Roberto Abraham, Yoshihisa Asada, Maruša Bradač, Gabriel Brammer et al.

We present the first self-consistent measurement of the Hα luminosity function over a wide redshift range, covering cosmic noon into the epoch of reionization. Our analysis utilizes a novel method based on James Webb Space Telescope (JWST) NIRCam medium-band imaging. We combine data from the CANUCS, JWST in Technicolor, and JUMPS surveys which offer deep, uniform imaging (29.5-30 AB, 3σ) with extensive NIRCam medium-band coverage, reaching up to 29 total filters (up to 20 JWST) when including an…

Read →
hep-phastro-ph.HE

Probing Memory-Burdened Primordial Black Holes with High-Energy Neutrinos

Arian Moradi Asl, Sandhya Choubey, Andreas Lund

The memory-burden effect can suppress the late-time evaporation of primordial black holes (PBHs), allowing those below the standard Hawking evaporation threshold to survive until the present epoch. These lighter PBHs emit high and ultra-high-energy neutrinos, opening the tentalizing possibility of discovery via neutrino telescopes. We study the constraints on memory-burdened PBHs from current IceCube HESE, MESE, and EHE data; and forecast the sensitivity reach of IceCube-Gen2 radio and GRAND200k…

Read →
physics.space-ph

Skills for forecasting space weather

H. J. Austin, N. P. Savani

Coronal mass ejections (CMEs) from the Sun can have severe impacts on the Earth environment in the form of geomagnetic storms. These storms pose a risk to the global technological infrastructure, making the prediction of these events imperative. In this paper, we have broadened the statistical verification of the Bz4Cast tool, the first empirically-driven model to forecast solar wind magnetic vectors inside a CME prior to their Earth arrival. Twenty five CME events (between 2012 and 2016) have b…

Read →
astro-ph.GAastro-ph.HE

Diagnosing the Fe line complex of the intracluster medium by XRISM high-resolution spectroscopy

K. Fukushima, L. Hirata, N. Y. Yamasaki, P. Chakraborty, S. Dupourqué, Y. Fujita, L. Gu, C. Kilbourne et al.

We aim to test the validity of the CIE framework in the ICM by performing line diagnostics based mainly on resolved Fe-K emission lines. Methods. We analyse Resolve full-array spectra of 17 galaxy clusters. Prominent Fe-K line components (the Fe xxv w, x, y, z, and Fe xxvi Lyα1,2 lines) are removed from plasma emission models and instead fitted with Gaussian profiles, enabling direct measurements of line fluxes without relying on synthetic spectral models. Some cool-core systems show w/z ratios…

Read →
astro-ph.GA

Breathing Fire: Hot Dust in the Big Three Dragons at z = 7.15

Gitanjali Rajulal, Hiddo S. B. Algera, Yuma Sugahara, Tom J. L. C. Bakx, Takuya Hashimoto, Suzuka Arai, Akio K. Inoue, Ikki Mitsuhashi et al.

We present new Atacama Large Millimeter/submillimeter Array (ALMA) Band 9 ($λ_\mathrm{obs} = 0.45\,\mathrm{mm}$) and 4 ($λ_\mathrm{obs} = 2.2\,\mathrm{mm}$) observations towards the Big Three Dragons, a pair of merging Lyman-break galaxies (LBGs) at $z=7.15$. The system was previously detected in ALMA Bands 6, 7 and 8 ($λ_\mathrm{obs} = 0.73 - 1.32\,\mathrm{mm}$), which, combined with our new observations, allows us to robustly constrain its dust temperature and obscured SFR. The unresolved Band…

Read →
astro-ph.GA

First detection of C2H+ in the interstellar medium

Arshia M. Jacob, Karl M. Menten, Sandra Brünken, Arnaud Belloche, Friedrich Wyrowski, Weslley G. D. P. Silva, Oskar Asvany, Sarwar Khan et al.

Despite the detection of nearly 350 molecules in the interstellar medium, almost half of which are carbon chains, the pathways that build molecular complexity remain poorly understood. Observed abundances of carbon-chain and aromatic species are difficult to reconcile with existing top-down or bottom-up formation scenarios, due in part to limited observational constraints and incomplete theoretical understanding. In particular, small intermediary ions, key drivers of ion-molecule reactions capab…

Read →
astro-ph.SRastro-ph.GA

JWST Reveals a Galaxy-Wide Association of Red Supergiants with OB Stars in NGC 5584

Min Dai, Shu Wang, Biwei Jiang

The spatial relationship between young and evolved massive-star tracers offers a means of probing recent star formation across galactic disks. We combine JWST/NIRCam, $Swift$/UVOT UVW2, and GALEX FUV/NUV images to investigate the spatial association between red-supergiant (RSG) candidates and UV-selected star-forming complexes (SFCs) in the spiral galaxy NGC 5584. We identify 5,310 RSG candidates using colour--magnitude criteria and define 106 UV-selected SFCs from the UVOT/UVW2 morphology, with…

Read →
astro-ph.GAastro-ph.IM

A Two-level Radial-velocity Zero-point Calibration for LAMOST MRS with Gaia and APOGEE and a Value-added RV Catalogue

Jinming Zhang, Haibo Yuan

The LAMOST Medium-Resolution Survey (MRS) provides a large stellar spectroscopic data set for Galactic kinematics and time-domain radial-velocity (RV) studies. However, the multi-spectrograph, multi-exposure, multi-fiber observing strategy can imprint RV zero-point (RVZP) systematics that vary across instrumental and temporal hierarchies. We construct a two-level empirical RVZP correction to LAMOST DR12 MRS using Gaia DR3 magnitude-colour-corrected RVs and APOGEE DR17 RVs as external references:…

Read →
gr-qcastro-ph.HEhep-th

Gravitational radiation from binary systems with time varying masses

Teodora M. Matei, Cristian A. Croitoru, Tiberiu Harko

We consider the properties of the gravitational radiation emitted by massive stars in binary systems with time varying mass, orbiting around each other in Keplerian orbits under the influence of the gravitational force. When this effect is combined to the quadrupole expression of the gravitational radiation, some supplementary terms in the standard formulae describing radiative effects do appear. By using the generalized quadrupole formalism, with time dependent masses, we obtain the expressions…

Read →
astro-ph.IM

Spec-S5: A Next-Generation All-Sky Spectroscopic Facility Enabling Large-Scale Surveys for Cosmology and Astrophysics

Claire Poppett, David J. Schlegel, Arjun Dey, Klaus Honscheid, Paul Martini, Alex Drlica-Wagner, Pat Jelinsky, Chang-Jin Oh et al.

The Stage-5 Spectroscopic Experiment (Spec-S5) is a next-generation, all-sky spectroscopic facility designed to address fundamental questions in cosmology and astrophysics. Building on the legacy of the Dark Energy Spectroscopic Instrument (DESI), Spec-S5 will upgrade two existing 4-m telescopes into 6-m, wide-field observatories, each equipped with a highly multiplexed spectrograph capable of measuring 13,000 spectra simultaneously. This overview paper summarizes the science motivation, system…

Read →
astro-ph.HE

Anisotropic Particle Transport from a Pulsar Wind Nebula Revealed by Einstein Probe and LHAASO

Zhen Cao, F. Aharonian, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, W. Bian et al.

Pulsar wind nebulae (PWNe) are major cosmic ray accelerators, yet the mechanisms transporting high-energy particles into the interstellar medium remain elusive. Building on the LHAASO discovery of an ultra-high-energy (UHE) $γ$-ray source near the bow-shock PWN powered by the pulsar PSR J1740+1000, we present a joint Einstein Probe (EP) and LHAASO study of this system. EP observations reveal an extended X-ray tail far exceeding the structure previously seen by XMM-Newton. Updated LHAASO observat…

Read →
astro-ph.SRastro-ph.GA

NATA: a chemical-picture equation of state for stellar merger hydrodynamics

Natalia Ivanova

We present NATA (Nearly Always Truthful Approximations), a self-contained chemical-picture equation of state for hydrogen-helium-carbon-oxygen mixtures, developed for hydrodynamics calculations of stellar mergers and common envelope evolution. NATA carries bound species explicitly in ionisation and dissociation equilibrium and evaluates pressure, internal energy, and entropy from one continuous, single-physics chemical-picture solve built on analytic and semi-analytic component physics, rather t…

Read →
astro-ph.EP

What can Planetary Ice Shells Teach Us about Ocean Mixing and Life, and Why Salt Matters

Nicole Shibley

Past and present climates, both on Earth and in planetary systems, maintain ice covers with underlying oceans. This can range from sea ice in the Arctic Ocean to global ice shells on ice-covered moons in the Solar System to ice sheets in past episodes of Earth's history. When an ice shell overlies an ocean, it becomes challenging to infer what ocean processes could be going on below as in-situ ocean measurements are often lacking. This means that what we learn about ocean mixing must often be in…

Read →
astro-ph.HEastro-ph.IM

Insights into the Pulsar Timing Array hypothesis space

El Mehdi Zahraoui, Patricio Maturana-Russel, Willem van Straten, Renate Meyer, Sergei Gulyaev

We present novel insights into the pulsar-noise model space in pulsar timing array (PTA) experiments. Through a comparative analysis of the same Parkes PTA second data release observations processed with the 2020 and 2023 pipelines, we show that data processing materially changes the distribution of posterior support across competing noise hypotheses and increases sensitivity to weak contributions such as the solar wind. A solar-wind component appears in the highest-posterior hypothesis for ten…

Read →
astro-ph.IM

Overview and status of BICEP Array's BA4-90/150 CMB polarimeter

M. A. Petroff, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck et al.

The inflation paradigm postulates a period of rapid expansion in the early Universe, which would generate gravitational waves. These tensor perturbations would produce a faint B-mode signature in the polarization of the cosmic microwave background (CMB), but this signal is orders of magnitude weaker than that from the CMB's other anisotropy and that from astrophysical foregrounds. Placing more-stringent upper limits on this signal or making a definitive detection thus requires exceptional contro…

Read →
astro-ph.SR

The $δ$ Scuti pulsator occurrence as a function of age, $T_{\rm eff}$, rotation, and metallicity

Ian Berry, Daniel Huber, Yaguang Li, Daniel Hey, Timothy R. Bedding, Simon J. Murphy

Many A- and F- type stars do not display $δ$ Scuti pulsations, despite being located within the instability strip. We use photometry from the TESS Mission to discover and study $δ$ Scuti pulsators in open clusters within 500 pc and with ages between ~20 and 900 Myr, which provide a unique opportunity to study $δ$ Scuti pulsators in coeval populations with uniform chemical composition. We measure pulsator occurrence, which corrects the pulsator fraction for incompleteness, across all clusters. We…

Read →
astro-ph.HE

A Systematic Study of Type Ia Supernova Remnants: Using Nucleosynthesis to Probe their Supernova Progenitors

Cole Treyturik, Samar Safi-Harb, Gilles Ferrand

We present the first systematic, spatially resolved X-ray spectroscopic study of a largely thermonuclear (Type Ia) sample of supernova remnants (SNRs), aimed at probing the explosion properties and progenitors through a comparison to a suite of nucleosynthesis models available in the literature. Our sample focuses on Galactic and LMC ejecta-dominated SNRs believed to be, or otherwise assumed to be, of thermonuclear origin. Using archival XMM-Newton observations (and Chandra for G1.9+0.3), we ext…

Read →
astro-ph.HEhep-ph

Neutrino quantum kinetics for fast flavor conversion in a time-dependent environment

Zewei Xiong, Meng-Ru Wu

Fast flavor conversions (FFCs) of neutrinos, driven by the fast flavor instability (FFI), can reshape the neutrino flavor content in dense astrophysical environments such as core-collapse supernovae and neutron star mergers. Most studies of FFCs adopt a two-step approach, in which a flavor-unstable state containing deep electron-minus-heavy-flavor lepton number (E-XLN) angular crossings is first constructed and subsequently evolved. Because realistic crossings should instead develop gradually th…

Read →