EVIDENCE FOR THE GALACTIC ORIGIN OF GAMMA-RAY BURSTS

We propose a new criterion to divide the classical gamma-ray bursts in to two classes on the basis of their distribution in the duration-hard ness plane. We study the two proposed classes separately, dividing the m into subsets of different hardness-ratio ranges. The intensity distr ibution (log N vs. log S) and the corresponding space distribution of the subsets provide us with a different scenario for each of the two c lasses. For the first time, in both cases, clear indications for a Gal actic origin of gamma-ray bursts have been found. Two possibilities ar e favored: (1) two kinds of Galactic gamma-ray bursts coming from the disk and from the halo, respectively, and (2) two kinds of gamma-ray b ursts deriving from two distinct source populations located at differe nt positions in the Galactic disk.