Gamma ray bursts (GRBs) were first detected serendipitously in 1967 by gamma ray detectors aboard the Vela satellites, and were announced by Klebesadel et al. in 1973. Work by Enrico Costa and Gerald J Fishman in the last two decades have demonstrated that GRBs are of cosmological origin, and are the brightest sources known in the universe.
GRBs are intense flashes of gamma rays emanating from cosmic sources lasting for a few seconds to minutes. During the flash, a GRB outshines any stars and any galaxies in the universe. We now know that the sources of GRBs reside in distant galaxies and that they appear so bright because they emit narrow beams of relativistic particles, and those that are observed happen to have these beams directed toward Earth. We also know that there are at least two distinct types of GRBs. The long-duration bursts are associated with rare types of supernova explosions and may be caused by the formation of a black hole at the centre of a collapsing massive star. The short-duration bursts may be caused by the merger of two neutron stars.