Search Publications
Hard X-Rays and Fluorescent Iron Emission from the Embedded Infrared Cluster in NGC 2071
Skinner, Stephen L.; Güdel, Manuel; Audard, Marc +1 more
We present first results of XMM-Newton X-ray observations of the infrared cluster lying near the NGC 2071 reflection nebula in the Orion B region. This cluster is of interest because it is one of the closest regions known to harbor embedded high-mass stars. We report the discovery of hard X-ray emission from the dense central NGC 2071-IR subgroup,…
Optical Variability of Infrared Power-Law-Selected Galaxies and X-Ray Sources in the GOODS-South Field
Sarajedini, Vicki; Klesman, Alison
We investigate the use of optical variability to identify and study active galactic nuclei (AGNs) in the GOODS-South field. A sample of 22 mid-IR power-law sources and 102 X-ray sources with optical counterparts in the HST ACS images were selected. Each object is classified with a variability significance value related to the standard deviation of…
A Robust Test of Evolution near the Tip of the Red Giant Branch and Missing Giants in NGC 2808
Martel, André R.; Sandquist, Eric L.
We describe a new method for robustly testing theoretical predictions of red giant evolution near the tip of the giant branch. When theoretical cumulative luminosity functions are shifted to align the tip in the I band and normalized at a luminosity level slightly brighter than the red giant bump, virtually all dependence on age and composition (h…
Multiwavelength Monitoring of the Unusual Ultraluminous Supernova SN 1978K in NGC 1313 and the Search for an Associated Gamma-Ray Burst
Pakull, M.; Böttcher, M.; Ryder, S. D. +4 more
We discuss our radio (Australia Telescope Compact Array and Australian Long Baseline Array) and X-ray (XMM-Newton) monitoring observations of the unusual ultraluminous supernova SN 1978K in NGC 1313 at ~25 yr after the explosion. SN 1978K is a rare example of a Type IIn supernova that has remained bright enough to have long-term X-ray and radio ob…
On the Mass and Energy Loading of Extreme-UV Bright Points
McIntosh, Scott W.
We discuss the appearance of extreme-ultraviolet (EUV) bright points (BPs) in the analysis of long-duration observations in the He II 304 Å passband of the Solar and Heliospheric Observatory Extreme-ultraviolet Imaging Telescope (SOHO EIT). The signature of the observed 304 Å passband intensity fluctuations around the BPs suggests that the primary…
XMM-Newton Observations of Nova Sagittarii 1998
Hernanz, M.; Sala, G.
We report on X-ray observations of Nova Sagittarii 1998 (V4633 Sgr) performed with XMM-Newton at three different epochs, 934, 1083, and 1265 days after discovery. The nova was detected with the EPIC cameras at all three epochs, with emission spanning the whole energy range from 0.2 to 10 keV. The X-ray spectra do not change significantly at the di…
Kinematics of the Broad-Line Region in M81
Devereux, Nick; Shearer, Andrew
A new model is presented that explains the origin of the broad emission lines observed in the LINER/Seyfert nucleus of M81 in terms of a steady state spherically symmetric inflow, amounting to ~1×10-5 Msolar yr-1, which is sufficient to explain the luminosity of the active galactic nucleus (AGN). The emitting volum…
GRB 050713A: High-Energy Observations of the Gamma-Ray Burst Prompt and Afterglow Emission
Gehrels, N.; Pagani, C.; Stamerra, A. +14 more
Swift discovered GRB 050713A and slewed promptly to begin observing with its narrow-field instruments 72.6 s after the burst onset, while the prompt gamma-ray emission was still detectable in the BAT. Simultaneous emission from two flares is detected in the BAT and XRT. This burst marks just the second time that the BAT and XRT have simultaneously…
Lensing Signals in the Hubble Ultra Deep Field Using All Second-Order Shape Deformations
Anderson, Jay; Irwin, John; Shmakova, Marina
The long exposure times of the Hubble Ultra Deep Field (UDF) together with empirically derived position-dependent point-spread functions have enabled us to measure two distinct nonlinear shape distortions of galaxies. We have previously argued that nonlinear lensing from small (109-1010 Msolar) dense objects in the…
A Search for Lyman Break Galaxies at z>8 in the NICMOS Parallel Imaging Survey
Teplitz, Harry I.; Siana, Brian; Malkan, Matthew A. +4 more
We have selected 14 J-dropout Lyman break galaxy (LBG) candidates with J110-H160>=2.5 from the NICMOS Parallel Imaging Survey. This survey consists of 135 arcmin2 of imaging in 228 independent sight lines, reaching average 5 σ sensitivities of J110=25.8 and H160=25.6 (AB). Distinguishing th…