Michael R. Goad

Learn More
Gamma-ray burst (GRB) afterglows have provided important clues to the nature of these massive explosive events, providing direct information on the nearby environment and indirect information on the central engine that powers the burst. We report the discovery of two bright x-ray flares in GRB afterglows, including a giant flare comparable in total energy(More)
We present observations of the early X-ray emission for a sample of 40 gamma-ray bursts (GRBs) obtained using the Swift satellite, for which the narrow-field instruments were pointed at the burst within 10 minutes of the trigger. Using data from the Burst Alert Telescope and the X-Ray Telescope, we show that the X-ray light curve can be well described by an(More)
G. Tagliaferri, M. Goad, G. Chincarini, A. Moretti, S. Campana, D. N. Burrows, M. Perri, S. D. Barthelmy, N. Gehrels, H. Krimm, T. Sakamoto, P. Kumar, P. I. Mészáros, S. Kobayashi, B. Zhang, L. Angelini, P. Banat, A. P. Beardmore, M. Capalbi, S. Covino, G. Cusumano, P. Giommi, O. Godet, J. E. Hill, J. A. Kennea, V. Mangano, D. C. Morris, J. A. Nousek, P. T.(More)
Until recently, X-ray flares during the afterglow of gamma-ray bursts (GRBs) were a rarely detected phenomenon; thus, their nature is unclear. During the afterglow of GRB 050502B, the largest X-ray flare ever recorded rose rapidly above the afterglow light curve detected by the SwiftX-Ray Telescope. The peak flux of the flare was >500 times that of the(More)
Gamma-ray bursts (GRBs) come in two classes: long (> 2 s), soft-spectrum bursts and short, hard events. Most progress has been made on understanding the long GRBs, which are typically observed at high redshift (z approximately 1) and found in subluminous star-forming host galaxies. They are likely to be produced in core-collapse explosions of massive stars.(More)
We carefully reconsider the problem of classifying broad absorption line quasars (BALQSOs) and derive a new, unbiased estimate of the intrinsic BALQSO fraction from the SDSS DR3 QSO catalogue. We first show that the distribution of objects selected by the so-called “absorption index” (AI) is clearly bimodal in logAI, with only one mode corresponding to(More)
GRB 050911, discovered by the Swift Burst Alert Telescope, was not seen 4.6 hr later by the Swift X-ray Telescope, making it one of the very few X-ray non-detections of a Gamma-Ray Burst (GRB) afterglow at early times. The γ-ray light-curve shows at least three peaks, the first two of which (∼T0 − 0.8 and T0 + 0.2 s, where T0 is the trigger time) were(More)
We have applied a Learning Vector Quantization (LVQ) algorithm to SDSS DR5 quasar spectra in order to create a large catalogue of broad absorption line quasars (BALQSOs). We first discuss the problems with BALQSO catalogues constructed using the conventional balnicity and/or absorption indices (BI and AI), and then describe the supervised LVQ network we(More)
Two short (< 2 s) gamma-ray bursts (GRBs) have recently been localized and fading afterglow counterparts detected. The combination of these two results left unclear the nature of the host galaxies of the bursts, because one was a star-forming dwarf, while the other was probably an elliptical galaxy. Here we report the X-ray localization of a short burst(More)
The bright gamma-ray burst GRB 050525a has been detected with the Swift observatory, providing unique multiwavelength coverage from the very earliest phases of the burst. The X-ray and optical/UVafterglow decay light curves both exhibit a steeper slope 0.15 days after the burst, indicative of a jet break. This jet break time combined with the total(More)