Search Publications
Broad Relativistic Iron Emission Line Observed in SAX J1808.4-3658
Altamirano, D.; Wijnands, R.; Miller, J. M. +4 more
During the 2008 September-October outburst of the accreting millisecond pulsar SAX J1808.4-3658, the source was observed by both Suzaku and XMM-Newton approximately 1 day apart. Spectral analysis reveals a broad relativistic Fe Kα emission line which is present in both data sets, as has recently been reported for other neutron star low-mass X-ray …
Probing The Intergalactic Medium-Galaxy Connection At z < 0.5. I. A Galaxy Survey In Qso Fields And A Galaxy-Absorber Cross-Correlation Study
Chen, Hsiao-Wen; Mulchaey, John S.
We present an imaging and spectroscopic survey of galaxies in fields around QSOs HE 0226-4110, PKS 0405-123, and PG 1216+069. The fields are selected to have ultraviolet echelle spectra available, which uncover 195 Lyα absorbers and 13 O VI absorbers along the three sightlines. We obtain robust redshifts for 1104 galaxies of rest-frame absolute ma…
Dynamics of Galactic Disks and Mergers at z ~ 1.6: Spatially Resolved Spectroscopy with Keck Laser Guide Star Adaptive Optics
Erb, Dawn K.; Shapley, Alice E.; Steidel, Charles C. +3 more
We present 0farcs2 resolution near-infrared integral field spectroscopy of Hα emission from six star-forming galaxies at z ~ 1.6 (a look-back time of ~9.6 Gyr). These observations were obtained with OSIRIS using the Keck Laser Guide Star Adaptive Optics system. All sources have a compact spatial extent of ~1'', with an average half-light radius of…
Variability Timescales in the M87 Jet: Signatures of E 2 Losses, Discovery of a Quasi Period in HST-1, and the Site of TeV Flaring
Cheung, C. C.; Stawarz, Łukasz; Harris, D. E. +2 more
We investigate the variability timescales in the jet of M87 with two goals. The first is to use the rise times and decay times in the radio, ultraviolet, and X-ray light curves of HST-1 to constrain the source size and the energy loss mechanisms affecting the relativistic electron distributions. HST-1 is the first jet knot clearly resolved from th…
The Extended Environment of M17: A Star Formation History
Bieging, John H.; Kang, Miju; Indebetouw, Rémy +9 more
M17 is one of the youngest and most massive nearby star-formation regions in the Galaxy. It features a bright H II region erupting as a blister from the side of a giant molecular cloud (GMC). Combining photometry from the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) with complementary infrared (IR) surveys, we identif…
1.75 h -1 kpc Separation Dual Active Galactic Nuclei at z = 0.36 in the Cosmos Field
Davis, Marc; Griffith, Roger L.; Stern, Daniel +4 more
We present strong evidence for dual active galactic nuclei (AGNs) in the z = 0.36 galaxy COSMOS J100043.15+020637.2. COSMOS Hubble Space Telescope (HST) imaging of the galaxy shows a tidal tail, indicating that the galaxy recently underwent a merger, as well as two bright point sources near the galaxy's center. The luminosities of these sources (d…
The Masses of Population II White Dwarfs
Bergeron, P.; Rich, R. Michael; Hansen, Brad M. S. +4 more
Globular star clusters are among the first stellar populations to have formed in the Milky Way, and thus only a small sliver of their initial spectrum of stellar types are still burning hydrogen on the main sequence today. Almost all of the stars born with more mass than 0.8 M sun have evolved to form the white dwarf cooling sequence of…
Study on X-Ray Spectra of Obscured Active Galactic Nuclei Based on Monte Carlo Simulation—An Interpretation of Observed Wide-Band Spectra
Terashima, Yuichi; Ikeda, Shinya; Awaki, Hisamitu
Monte Carlo simulation is one of the best tools to study the complex spectra of Compton-thick active galactic nuclei (AGNs) and to figure out the relation between their nuclear structures and X-ray spectra. We have simulated X-ray spectra of Compton-thick AGNs obscured by an accretion torus whose structure is characterized by a half-opening angle,…
Discovery of an Unusual Optical Transient with the Hubble Space Telescope
Huang, X.; Lidman, C.; Amanullah, R. +27 more
We present observations of SCP 06F6, an unusual optical transient discovered during the Hubble Space Telescope Cluster Supernova Survey. The transient brightened over a period of ~100 days, reached a peak magnitude of ~ 21.0 in both i 775 and z 850, and then declined over a similar timescale. There is no host galaxy or progen…
Disk-Jet Connection in the Radio Galaxy 3C 120
Peterson, Bradley W.; McHardy, Ian M.; Gaskell, C. Martin +33 more
We present the results of extensive multi-frequency monitoring of the radio galaxy 3C 120 between 2002 and 2007 at X-ray (2-10 keV), optical (R and V bands), and radio (14.5 and 37 GHz) wave bands, as well as imaging with the Very Long Baseline Array (VLBA) at 43 GHz. Over the 5 yr of observation, significant dips in the X-ray light curve are foll…