UchUchU

Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.SRphysics.plasm-phphysics.space-ph

Direct Measurement of Diffusion Coefficients: Evidence for Diffusive Stochastic Heating in Collisionless Plasmas

Tamar Ervin, Trevor A. Bowen, Alfred Mallet, Philip A. Isenberg, Kristopher G. Klein, Stuart D. Bale, Benjamin D. G. Chandran, Roberto Livi et al.

Open questions in collisionless plasma dissipation can be addressed using space-based observations in different astrophysical environments, with implications for both astrophysical and laboratory plasma systems. We study a low-$β$, highly imbalanced, sub-Alfvénic stream observed by Parker Solar Probe (PSP) to identify and distinguish between signatures of stochastic heating (SH) and resonant heating (RH) by parallel ion cyclotron waves (ICWs). Prior work studying this stream (Bowen et al., 2025)…

Read →
astro-ph.GA

Electron Density of Ionized Gas Outflows: Insights from the MaNGA Survey

Andrew Weldon, Casey Papovich, Justin Spilker, Robert C. Kennicutt

We investigate the properties of ionized gas outflows in nearby star-forming galaxies from the final Data Release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) Survey. Using spatially resolved spectroscopy, we search for signatures of ionized outflows within physically motivated outflow apertures. We find significant evidence for additional broad H$α$, [N II]$λλ$6550,6584, and [S II]$λλ$6718,6733 emission-line components in 115 galaxies, $\sim$3% of star-forming MaNGA galaxi…

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

Ardua: Unveiling the Baryon Cycle from Stars to the Cosmic Web

Carlos J. Vargas, Caroline Kilbourne, Haeun Chung, Erika Hamden, Ralph Kraft, Joseph N. Burchett, Lauren Corlies, Claude-André Faucher-Giguère et al.

The circumgalactic medium (CGM) -- the multiphase gas reservoirs surrounding galaxies -- remains the least understood component of the baryon cycle governing galaxy growth, despite its central role in the Astro2020 Decadal Survey's priorities. Existing constraints come almost exclusively from pencil-beam absorption spectroscopy, leaving the spatial structure, kinematics, and phase interactions of CGM gas fundamentally unmapped. We present Ardua, a mission concept for NASA's ASTRA Initiative that…

Read →
astro-ph.COastro-ph.GAastro-ph.IMgr-qc

Reconstructing the kinematics of Laniakea using Type Ia Supernovae

Francesco Sorrenti, Erick Pastén, Leonardo Giani

We develop a kinematic framework that relates the monopole, dipole, and quadrupole of the luminosity distance to an ellipsoidal peculiar velocity field describing the dynamics of the Laniakea supercluster. By properly accounting for the transformations between the CMB and Laniakea reference frames and selecting Type Ia supernovae within the volume associated with the superstructure, we show that luminosity distance multipoles encode the expansion and shear of the local velocity field. This allow…

Read →
astro-ph.EP

Ice Deposition Fronts In Porous Bodies From Transient Heating Events In a Protoplanetary Disk

Stephen Li, Alice C. Quillen, Adam E. Rubinstein, Dominique Segura-Cox, Kevin Righter

Using a 1D mass and heat transport model, we numerically integrate heat flow and gas transport in a porous body exposed to a transient heating event while embedded in a protoplanetary disk. When small icy grains are heated, volatiles sublimate, enriching the disk with volatile gases. When a porous body enters this heated, volatile-rich environment, volatile gases diffuse throughout the cool, porous body and deposit ice where the partial pressure of a volatile exceeds its vapor pressure. We simul…

Read →
astro-ph.IM

WALOP-South: a four camera one shot imaging polarimeter for the PASIPHAE survey. Paper III -- PSF modelling

Indrajit Paul, Kishan Deka, Tuhin Ghosh, Siddharth Maharana, A. N. Ramaprakash, Ramya M. Anche, Artem Basyrov, Dmitry Blinov et al.

The two WALOP instruments, built for the PASIPHAE survey, will measure the linear polarization of large numbers of stars in the Galactic polar regions in the SDSS-$r$ band. They are designed with a wide field-of-view, enabling measurement of the Stokes parameters $I$, $q$, and $u$ for multiple stars simultaneously within a $35^\prime \times 35^\prime$ region of sky for WALOP-South and $30^\prime \times 30^\prime$ region for WALOP-North. In this paper, we present a polar shapelet-based PSF photom…

Read →
astro-ph.SR

Time-Resolved Connection between Starspots and Flares in Nearby Young Solar-type Stars Observed by TESS

Daijiro Hitotsuyanagi, Hiroto Yamada, Daisuke Yamashiki, Kazuma Ishihara, Yosuke Yamashiki, Kosuke Namekata

Superflares are energetic explosions on stellar surface with energies of 10^33-10^36 erg, significantly exceeding those of typical solar flares. While previous studies have suggested that these events are driven by magnetic energy stored in large starspots, the detailed time-resolved relationship between starspot area and flare activity on individual stars has remained unclear. In this paper, we investigate the time evolution of magnetic activity on three representative young solar-type stars (E…

Read →