To the Swift

The Swift Gamma Ray Burst Explorer satellite detected in February of 2006 the longest-lasting burst so far, labelled GRB060218, more than 2000 seconds long. Such gamma ray bursts are known to result from stars more massive than 25 solar masses which undergo core collapse, resulting in a highly relativistic jet which produces the gamma-rays, and at the same time the star ejects its outer envelope in a supernova explosion. While the gamma-rays from jets have been extensively studied, this is the first time that the supernova explosion has been observed as it breaks out from the opaque stellar wind of the progenitor star. Swift’s sensitive X-ray detectors observed a characteristic black-body emission, which starts out weak compared to the non-thermal gamma/X spectrum of the jet burst, and becomes dominant by the time the jet burst ends, indicating the break-out of the supernova shock wave. Members of the Swift Penn State team published these results in a recent issue of Nature (vol. 442, p. 1008, August 31, 2006).