The Short Burst Revolution

Gamma-ray bursts (GRBs) are among the most energetic explosions in the Universe. They are generally divided into two main classes: long duration-soft spectrum bursts, which last ~2 to hundreds of seconds; and, short duration-hard GRBs, which last less than 2 seconds and are spectrally “harder” than the first class. Over the past few years, the long-soft GRBs have been shown to be associated with supernovae, and to originate in star forming galaxies at redshifts z=0.1 to 6.3. It is generally accepted that these events result from the collapse of a very massive star (Woosley, S. and Bloom, J. Annual Reviews of Astronomy and Astrophysics, in press), but until summer 2005, very little was known of the progenitors of short-hard GRBs.