THE WIDTH OF THE GAMMA-RAY BURST LUMINOSITY FUNCTION

We examine the width of the gamma-ray burst (GRB) luminosity function through the distribution of GRB peak count rates, C-peak, as detected by BATSE (1993). In the context of Galactic corona spatial distributio n models, we attempt to place constraints on the characteristic width of the luminosity function by comparing the observed intensity distrib ution with those produced by a range of density and luminosity functio ns. We find that the intrinsic width of the luminosity function cannot be very well restricted. However, the distribution of intrinsic lumin osities of detected bursts can be limited: we find that most observed bursts have luminosities that are in a range of one to two decades, bu t a significant population of undetected less luminous bursts cannot b e excluded. These findings demonstrate that the assumption that GRB ar e standard candles is sufficient but not necessary to explain the obse rved intensity distribution. We show that the main reason for the rela tively poor constraints is the fact that the bright-end part of the GR B flux distribution is not yet sampled by BATSE, and better sampling i n the future may lead to significantly stronger constraints on the wid th of the luminosity function.