Gravitational collapse as the source of gamma-ray bursts
  If the threshold for $e^{-}e^{+}$ pair production depends on an angle between photon momenta, and if the $\gamma$-rays are collimated right in gamma-ray burst (GRB) source then another solution of the compactness problem is possible. The list of basic assumptions of the scenario describing the GRB with energy release $< 10^{49}$ erg is adduced: the matter is about an alternative to the ultrarelativistic fireball if all long-duration GRBs are physically connected with core-collapse supernovae (SNe). The questions about radiation pressure and how the jet arises on account of even a small radiation field asymmetry in a compact GRB source of size $\lesssim 10^8$ cm, and observational consequences of the compact model of GRBs are considered. 
V.V.Sokolov