Search Publications
A Search for Discrete X-Ray Spectral Features in a Sample of Bright γ-Ray Burst Afterglows
Sako, Masao; Harrison, Fiona A.; Rutledge, Robert E.
We present uniform, detailed spectral analyses of γ-ray burst (GRB) X-ray afterglows observed with ASCA, BeppoSAX, Chandra, and XMM-Newton and critically evaluate the statistical significances of X-ray emission and absorption features in these spectra. The sample consists of 21 X-ray afterglow observations up to and including that of GRB 040106 wi…
UV Continuum Spectroscopy of a 6L* z = 5.5 Starburst Galaxy1,
Rosati, P.; Fazio, G. G.; van der Wel, A. +10 more
We have obtained a high S/N (22.3 hr integration) UV continuum VLT FORS2 spectrum of an extremely bright (z850=24.3) z = 5.515 +/- 0.003 star-forming galaxy (BD38) in the field of the z = 1.24 cluster RDCS 1252.9-2927. From HST Advanced Camera for Surveys imaging, this object was selected as a potential z ~ 6 Lyman break galaxy (LBG) ba…
XMM-Newton Spectroscopy of the Starburst-Dominated Ultraluminous Infrared Galaxy NGC 6240
Lutz, D.; Kaspi, Shai; Turner, T. J. +5 more
We present a new XMM-Newton observation of the ultraluminous infrared galaxy (ULIRG) NGC 6240. We analyze the reflecting grating spectrometer (RGS) data, as well as data from the other instruments, and find a starburst-dominated 0.5-3 keV spectrum with global properties resembling those observed in M82 but with a much higher luminosity. We show th…
The Look-back Time Evolution of Far-Ultraviolet Flux from Elliptical Galaxies: The Fornax Cluster and A2670
Rey, Soo-Chang; Heckman, Timothy M.; Madore, Barry F. +30 more
In order to investigate the origin of the far-UV (FUV) flux from the early-type galaxies, the Galaxy Evolution Explorer is collecting the UV data for the elliptical-rich clusters at moderate redshifts (z<0.2) where the dominant FUV source is predicted to be hot horizontal-branch (HB) stars and their post-HB progeny. Here we present our first re…
Observations of an Emerging Flux Region Surge: Implications for Coronal Mass Ejections Triggered by Emerging Flux
Liu, Y.; Su, J. T.; Shibata, K. +2 more
It is well known that coronal mass ejections (CMEs) are often associated with flares and filament eruptions. Previous studies of CMEs, however, have not established any association between CMEs and surges. In this paper, we present a detailed analysis of a large emerging flux region (EFR) surge and a jetlike CME, both observed on 1998 April 16. Ou…
Bimodal Galaxies and Bimodality in Globular Cluster Systems
Forbes, Duncan A.
Various galaxy properties are not continuous over a large range in mass but rather reveal a remarkable transition or ``bimodality'' at a stellar mass of 3×1010 Msolar. These properties include colors, stellar populations, X-ray emission, and mass-to-light ratios. This behavior has been interpreted as the transition from hot t…
Pulse-Phase Spectroscopy of SMC X-1 with Chandra and XMM-Newton: Reprocessing by a Precessing Disk?
Hickox, R. C.; Vrtilek, S. D.
We present pulse-phase X-ray spectroscopy of the high-mass X-ray pulsar SMC X-1 from five different epochs, using Chandra X-Ray Observatory ACIS-S and XMM-Newton EPIC pn data. The X-ray spectrum consistently shows two distinct components, a hard power law and a soft blackbody with kTBB~0.18 keV. For all five epochs the hard component sh…
Discovery of a Light Echo from SN 2003gd
Sugerman, Ben E. K.
Archival HST/ACS data reveal details of a light echo around SN 2003gd in the galaxy M74, only the fifth supernova around which resolved echoes have been reported. An echo is detected 0.3" from the supernova between position angles of 250° and 360°, with a fainter signal present at a few other position angles. This material lies ~180 pc in front of…
The Ages of Elliptical Galaxies from Mid-Infrared Emission
Brighenti, Fabrizio; Mathews, William G.; Temi, Pasquale
The mid-infrared (10-20 µm) luminosity of elliptical galaxies is dominated by the integrated emission from circumstellar dust in red giant stars. As a single stellar population evolves, the rate of dusty mass loss from red giant stars decreases with time, so the mid-infrared luminosity should also decline with stellar age. To seek such a cor…
The X3 Flare of 2002 July 15
Li, Jing; LaBonte, B. J.; Mickey, D. L.
An X3-class flare occurred on 2002 July 15 with white-light emission and a complex filament eruption. Observations were made in the optical continuum, Hα, UV continuum, microwave, and soft X-rays, as well as with high-cadence longitudinal magnetograms. Within the preflare phase, intense heating is observed accompanying upward motion of the filamen…