Search Publications
Dependence of Chemical Abundance on the Cosmic-Ray Ionization Rate in IC 348
Li, Di; Wang, Junzhi; Yue, Nannan +8 more
Ions (e.g., ${{\rm{H}}}_{3}^{+}$ , H2O+) have been used extensively to quantify the cosmic-ray ionization rate (CRIR) in diffuse sightlines. However, measurements of the CRIR in low-to-intermediate density gas environments are rare, especially when background stars are absent. In this work, we combine molecular line observati…
The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER). V. The Structure of M33 in Resolved Stellar Populations
Bell, Eric F.; Williams, Benjamin F.; Choi, Yumi +14 more
We present a detailed analysis of the structure of the Local Group flocculent spiral galaxy M33, as measured using the Panchromatic Hubble Andromeda Treasury Triangulum Extended Region (PHATTER) survey. Leveraging the multiwavelength coverage of PHATTER, we find that the oldest populations are dominated by a smooth exponential disk with two distin…
CHIME Discovery of a Binary Pulsar with a Massive Nondegenerate Companion
Ransom, Scott M.; van Kerkwijk, M. H.; Kaspi, Victoria M. +25 more
Of the more than 3000 radio pulsars currently known, only ~300 are in binary systems, and only five of these consist of young pulsars with massive nondegenerate companions. We present the discovery and initial timing, accomplished using the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope, of the sixth such binary pulsar, PSR J2108…
AGN STORM 2. II. Ultraviolet Observations of Mrk 817 with the Cosmic Origins Spectrograph on the Hubble Space Telescope
Gorjian, Varoujan; Treu, Tommaso; Kaspi, Shai +62 more
We present reverberation mapping measurements for the prominent ultraviolet broad emission lines of the active galactic nucleus Mrk 817 using 165 spectra obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope. Our ultraviolet observations are accompanied by X-ray, optical, and near-infrared observations as part of the AGN Spac…
Catalog of Magnetic White Dwarfs with Hydrogen Dominated Atmospheres
Kepler, S. O.; Jordan, S.; Romero, A. D. +2 more
White dwarfs are excellent research laboratories as they reach temperatures, pressures, and magnetic fields that are unattainable on Earth. To better understand how these three physical parameters interact with each other and with other stellar features, we determined the magnetic field strength for a total of 804 hydrogen-rich white dwarfs (WDs) …
Finding r-II Sibling Stars in the Milky Way with the Greedy Optimistic Clustering Algorithm
Hattori, Kohei; Roederer, Ian U.; Okuno, Akifumi
R-process enhanced stars with [Eu/Fe] ≥ +0.7 (so-called r-II stars) are believed to have formed in an extremely neutron-rich environment in which a rare astrophysical event (e.g., a neutron-star merger) occurred. This scenario is supported by the existence of an ultra-faint dwarf galaxy, Reticulum II, where most of the stars are highly enhanced in…
Target-of-Opportunity Observation Detectability of Kilonovae with WFST
Dai, Zi-Gao; Zhao, Wen; Liu, Zheng-Yan +4 more
Kilonovae are approximately thermal transients, produced by the mergers of binary neutron stars (BNSs) and neutron star (NS)-black hole binaries. As the optical counterpart of the gravitational-wave event GW170817, AT2017gfo is the first kilonova detected with smoking-gun evidence. Its observation offers vital information for constraining the Hubb…
On the α/Fe Bimodality of the M31 Disks
Kobayashi, Chiaki; Gerhard, Ortwin; Arnaboldi, Magda +1 more
An outstanding question is whether the α/Fe bimodality exists in disk galaxies other than in the Milky Way. Here we present a bimodality using our state-of-the-art galactic chemical evolution models that can explain various observations in the Andromeda galaxy (M31) disks, namely, elemental abundances both of planetary nebulae and of red giant bra…
The Eruption of a Magnetic Flux Rope Observed by Solar Orbiter and Parker Solar Probe
Long, David M.; Davies, Emma E.; Berghmans, David +11 more
Magnetic flux ropes are a key component of coronal mass ejections, forming the core of these eruptive phenomena. However, determining whether a flux rope is present prior to eruption onset and, if so, the rope's handedness and the number of turns that any helical field lines make is difficult without magnetic field modeling or in situ detection of…
Inferences from Surface Brightness Fluctuations of Zwicky 3146 via the Sunyaev-Zel'dovich Effect and X-Ray Observations
Mroczkowski, Tony; Kraft, Ralph; Devlin, Mark +16 more
The galaxy cluster Zwicky 3146 is a sloshing cool-core cluster at z = 0.291 that in Sunyaev-Zel'dovich (SZ) imaging does not appear to exhibit significant pressure substructure in the intracluster medium. We perform a surface brightness fluctuation analysis via Fourier amplitude spectra on SZ (MUSTANG-2) and X-ray (XMM-Newton) images of this clust…