Physical restrictions on the models of gamma-ray bursts

Abstract

The present common view about GRB origin is related to cosmology. There are two evidences in favor of this interpretation. The first is connected with statistics, the second is based on measurements of the redshifts in the GRB optical afterglows. Redshifts in optical afterglows had been observed only in long GRB. Comparison of KONUS and BATSE data about statistics and hard X-ray lines is done, and some differences are noted. Hard gamma-ray afterglows, prompt optical spectra and polarization measurements could be very important for farther insight into GRB origin. Possibility of galactic origin of short GRB is discussed as well as their possible connection with soft gamma repeaters.