Search Publications
Structure and Morphology of X-Ray-selected Active Galactic Nucleus Hosts at 1 < z < 3 in the CANDELS-COSMOS Field
Fang, Guanwen; Kong, Xu; Chen, Yang +4 more
We analyze morphologies of the host galaxies of 35 X-ray-selected active galactic nuclei (AGNs) at z ~ 2 in the Cosmic Evolution Survey field using Hubble Space Telescope/WFC3 imaging taken from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. We build a control sample of 350 galaxies in total by selecting 10 non-active galaxies…
Phase-resolved XMM-Newton and Swift Observations of WR 25
Pandey, J. C.; Pandey, S. B.; Karmakar, Subhajeet
We present an analysis of long-term X-ray and optical observations of the Wolf-Rayet binary, WR 25. Using archival data from observations with the XMM-Newton and the Swift observatories, spanning over ~10 yr, we show that WR 25 is a periodic variable in X-rays with a period of 208 ± 3 days. X-ray light curves in the 0.5-10.0 keV energy band show p…
The WFPC2 Ultraviolet Survey: The Blue Straggler Population in NGC 5824
O'Connell, R. W.; Dalessandro, E.; Sanna, N. +3 more
We have used a combination of high-resolution Hubble Space Telescope Wide Field Planetary Camera 2 and wide-field ground-based observations, in ultraviolet and optical bands, to study the blue straggler star population of the massive outer halo globular cluster NGC 5824 over its entire radial extent. We have computed the center of the cluster and …
The Radial Distribution of X-Ray Binaries and Globular Clusters in NGC 4649 and their Relation with the Local Stellar Mass Density
Zezas, A.; Luo, B.; Gallagher, J. S. +7 more
We investigate the radial distribution of the low-mass X-ray binary (LMXB) population in the elliptical galaxy NGC 4649, using Chandra and Hubble data to separate the field and globular cluster (GC) populations. GCs with LMXBs have the same radial distribution as the parent red and blue GCs. The radial profile of field LMXBs follows the V-band pro…
Dramatic Change in Jupiter's Great Red Spot from Spacecraft Observations
de Pater, Imke; Wong, Michael H.; Orton, Glenn S. +5 more
Jupiter's Great Red Spot (GRS) is one of its most distinct and enduring features. Since the advent of modern telescopes, keen observers have noted its appearance and documented a change in shape from very oblong to oval, confirmed in measurements from spacecraft data. It currently spans the smallest latitude and longitude size ever recorded. Here …
The Second-generation z (Redshift) and Early Universe Spectrometer. I. First-light Observation of a Highly Lensed Local-ulirg Analog at High-z
Hasselfield, Matthew; Halpern, Mark; Menten, Karl M. +20 more
We recently commissioned our new spectrometer, the second-generation z(Redshift) and Early Universe Spectrometer (ZEUS-2) on the Atacama Pathfinder Experiment telescope. ZEUS-2 is a submillimeter grating spectrometer optimized for detecting the faint and broad lines from distant galaxies that are redshifted into the telluric windows from 200 to 85…
A Pulsation Search among Young Brown Dwarfs and Very-low-mass Stars
Cody, Ann Marie; Hillenbrand, Lynne A.
In 2005, Palla & Baraffe proposed that brown dwarfs (BDs) and very-low-mass stars (VLMSs; < 0.1 solar masses) may be unstable to radial oscillations during the pre-main-sequence deuterium burning phase. With associated periods of one to four hours, this potentially new class of pulsation offers unprecedented opportunities to probe the inter…
Astrometry, Radial Velocity, and Photometry: The HD 128311 System Remixed with Data from HST, HET, and APT
Cochran, William D.; Henry, Gregory W.; Benedict, G. Fritz +5 more
We have used high-cadence radial velocity measurements from the Hobby-Eberly Telescope with published velocities from the Lick 3 m Shane Telescope, combined with astrometric data from the Hubble Space Telescope (HST) Fine Guidance Sensors to refine the orbital parameters of the HD 128311 system, and determine an inclination of 55.°95 ± 14.°55 and …
High-energy X-Ray Detection of G359.89-0.08 (Sgr A-E): Magnetic Flux Tube Emission Powered by Cosmic Rays?
Hailey, Charles J.; Mori, Kaya; Bauer, Franz E. +11 more
We report the first detection of high-energy X-ray (E > 10 keV) emission from the Galactic center non-thermal filament G359.89-0.08 (Sgr A-E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to ~50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law s…
The X-Ray Spectrum of the Cooling-flow Quasar H1821+643: A Massive Black Hole Feeding Off the Intracluster Medium
Fabian, Andrew C.; Babul, Arif; Reynolds, Christopher S. +4 more
We present a deep Suzaku observation of H1821+643, an extremely rare example of a powerful quasar hosted by the central massive galaxy of a rich cooling-core cluster of galaxies. Informed by previous Chandra studies of the cluster, we achieve a spectral separation of emission from the active galactic nucleus (AGN) and the intracluster medium (ICM)…