Search Publications
The Central 300 pc of the Galaxy Probed by Infrared Spectra of H3 + and CO. III. Locations of Sgr B2 and Star Iota
Geballe, T. R.; Oka, Takeshi
Using a simple relation between the radial expansion velocity of diffuse gas in the Central Molecular Zone (CMZ) of the Galaxy and its distance from Sgr A* we estimate the physical depths within the CMZ of Star ι (2MASS J17470898-2829561) and two Sgr B2 far-infrared continuum sources with respect to the location of Sgr A*. To do this we…
Revisiting the Circumnuclear X-Ray Emission of NGC 2992 in a Historically Low State
Wang, Junfeng; Xu, Xiaoyu
The innermost region of the Seyfert galaxy NGC 2992 has long been suspected to be the location of intense AGN-host galaxy interaction, but photon pile up in previous high-resolution observations hampered the study of the soft X-ray excess and the interaction near its nucleus. We present an X-ray imaging and spectroscopic analysis of the circumnucl…
Numerical Modeling of Suprathermal Electron Transport in the Solar Wind: Effects of Whistler Turbulence with a Full Diffusion Tensor
Zank, Gary P.; Tang, Bofeng; Kolobov, Vladimir I.
The electron VDF in the solar wind consists of a Maxwellian core, a suprathermal halo, a field-aligned component strahl, and an energetic superhalo that deviates from the equilibrium. Whistler wave turbulence is thought to resonantly scatter the observed electron velocity distribution. Wave-particle interactions that contribute to Whistler wave tu…
Expediting DECam Multimessenger Counterpart Searches with Convolutional Neural Networks
Bechtol, K.; García-Bellido, J.; Soares-Santos, M. +11 more
Searches for counterparts to multimessenger events with optical imagers use difference imaging to detect new transient sources. However, even with existing artifact-detection algorithms, this process simultaneously returns several classes of false positives: false detections from poor-quality image subtractions, false detections from low signal-to…
Exploring Gravitationally Lensed z ≳ 6 X-Ray Active Galactic Nuclei Behind the RELICS Clusters
Bradač, Maruša; Strait, Victoria; Coe, Dan +5 more
Although observations of high-redshift quasars demonstrate that many supermassive black holes (BHs) reached large masses within one billion years after the Big Bang, the origin of the first BHs is still a mystery. A promising way to constrain the origin of the first BHs is to explore the average properties of z ≳ 6 BHs. However, typical BHs remain…
Faint Stars in a Faint Galaxy. II. The Low-mass Stellar Initial Mass Function of the Boötes I Ultrafaint Dwarf Spheroidal Galaxy
Wyse, Rosemary F. G.; Kozhurina-Platais, Vera; Platais, Imants +1 more
This paper presents improved constraints on the low-mass stellar initial mass function (IMF) of the Boötes I (Boo I) ultrafaint dwarf galaxy, based on our analysis of recent deep imaging from the Hubble Space Telescope. The identification of candidate stellar members of Boo I in the photometric catalog produced from these data was achieved using a…
Globular Cluster UVIT Legacy Survey (GlobULeS). III. Omega Centauri in Far-ultraviolet
Dalessandro, Emanuele; Rao, N. Kameswara; Hutchings, John +21 more
We present the first comprehensive study of the most massive globular cluster, Omega Centauri, in the far-ultraviolet (FUV), extending from the center to ~28% of the tidal radius using the Ultraviolet Imaging Telescope on board AstroSat. A comparison of the FUV-optical color-magnitude diagrams with available canonical models reveals that horizonta…
Magnetohydrodynamic Simulation of Multiple Coronal Mass Ejections: An Effect of "Pre-events"
Wood, Brian E.; Wu, Chin-Chun; Liou, Kan +1 more
Coronal mass ejections (CMEs) are a major source of solar wind disturbances that affect the space plasma and magnetic field environment along their propagation path. Accurate prediction of the arrival of a CME at Earth or any point in the heliosphere is still a daunting task. In this study we explore an often overlooked factor-the effects of "pre-…
Investigating the Observational Properties of Type Ib Supernova SN 2017iro
Kumar, Brajesh; Anupama, G. C.; Singh, Avinash +1 more
We report results of optical imaging and low-resolution spectroscopic monitoring of supernova (SN) 2017iro that occurred in the nearby (~31 Mpc) galaxy NGC 5480. The He I λ5876 feature present in the earliest spectrum (-7 days) classified it as a Type Ib SN. The follow-up observations span from -7 to +266 days with respect to the B-band maximum. W…
Galactic Winds across the Gas-rich Merger Sequence. II. Lyα Emission and Highly Ionized O VI and N V Outflows in Ultraluminous Infrared Galaxies
Tripp, Todd M.; Veilleux, Sylvain; Liu, Weizhe +3 more
This paper is the second in a series aimed at examining the gaseous environments of z ≤ 0.3 quasars and ultraluminous infrared galaxies (ULIRGs) as a function of AGN/host galaxy properties across the merger sequence. This second paper focuses on the Lyα emission and O VI 1032, 1038 and N V 1238, 1243 absorption features, tracers of highly ionized …