ON THE COSMOLOGICAL ORIGIN OF GAMMA-RAY BURSTS

Statistical properties of gamma-ray bursts are analyzed assuming that the bursters are cosmological. The model adopted is the simplest possible-it has no adjustable parameters. All the bursts are assumed to hc standard candles with identical power-law spectra. Their burst rate is assumed to be constant per unit comoving volume per unit comoving cosmological time in a Friedmann universe with OMEGA = 1 and LAMBDA = 0. The calculated distribution of burst intensities is consistent with that found by the BATSF experiment for the weak events and by the PVO for the strong events. The range of observations is estimated to be z(BATSE) almost-equal-to 1.5 and z(PVO) almost-equal-to 0.2. The rate of events is approximately 2 X 10(-6) yr-1 per L* galaxy, and approximately 3,000 yr-1 in the whole observable universe, and their peak luminosity is approximately 2 X 10(51) h100(-2) ergs s-1.