SNI: a new mechanism for gamma ray burst. I.Weak magnetic field

We propose a new mechanism for high energy gamma ray burst in Supernova type I (SNI) explosion. Presupernova is assumed to be a binary system comprised of a red giant and a white dwarf with a wind accretion. The accretion flow terminates by the accretion shock in the vicinity of the white dwarf at the distance of the order of the accretion radius. The gas inside the accretion radius constitutes the main body of a target for gamma ray production. The supernova explosion and the shock propagation in the white dwarf result in the hydrodynamical acceleration of the outer layers of the star. It proceeds in two stages. The first stage is caused by the shock propagating in the outer layers of the star; the second stage is connected with the adiabatic expansion of the ejected shell into low-density medium around the white dwarf. The spectrum of accelerated particles is steep and the maximum energy does not exceed 1000 GeV . The gamma ray burst is produced due to interaction of the accelerated particles with the gas in the binary system. Most of the photons have energies about 100 MeV , the total number of the emitted photons is between 10 46 and 10 47 . The typical duration of the burst is ∼ 1 − 3 s for ∼ 100 MeV photons and 10 − 3 s for ∼ 1 GeV photons. The calculations are valid in the case of a weak magnetic field. The case of strong magnetic field will be considered in part II (in preparation).