Search Publications
Focusing Cosmic Telescopes: Exploring Redshift z ~ 5-6 Galaxies with the Bullet Cluster 1E0657 - 56
Treu, Tommaso; Bradač, Maruša; Applegate, Douglas +7 more
The gravitational potential of clusters of galaxies acts as a cosmic telescope allowing us to find and study galaxies at fainter limits than otherwise possible and thus probe closer to the epoch of formation of the first galaxies. We use the Bullet cluster 1E0657 - 56 (z = 0.296) as a case study, because its high mass and merging configuration mak…
The First Swift Ultraviolet/Optical Telescope GRB Afterglow Catalog
Cucchiara, A.; Brown, P. J.; Page, M. J. +21 more
We present the first Swift Ultraviolet/Optical Telescope (UVOT) gamma-ray burst (GRB) afterglow catalog. The catalog contains data from over 64,000 independent UVOT image observations of 229 GRBs first detected by Swift, the High Energy Transient Explorer 2 (HETE2), the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), and the Interplane…
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,…