Cosmic gamma-ray bursts
Lomonosov Moscow State University, Department of Physics, Leninskie Gory 1 build. 2, Moscow, 119991, Russian Federation
The results of the observation of cosmic gamma-ray bursts are discussed and available theoretical models are presented. Emphasis is placed on a cosmological model in which a gamma burst results from a powerful (~ 1051-1053 erg) and very short ( ~10-100 s) energy release which occurs in a compact ( ~ 106-107 cm) region and gives rise to a photon-lepton fireball expanding at an ultrarelativistic velocity (Lorentz-factor Γ \geqslant 100). The interaction of the relativistic shock wave with its environment produces the observed X-ray and optical afterglows of a burst. Possible physical models of such an energy release event are discussed and some related problems considered.