Gamma ray gun in the center of the Galaxy

Paper discusses a model of physical processes that occur in the center of the Galaxy and cause the emission of the 511 keV annihilation γ-ray line and of the continuous γ-ray spectrum. According to the hypothesis suggested in the paper, electron-positron pairs, whose annihilation produces the γ-ray line and the continuum, are formed when a gas-cloud target is irradiated by a directed beam of hard (approximately 100 MeV) gamma-ray quanta. A model is developed of how a γ-ray beam (gamma-ray gun) is formed near a supermassive rotating black hole surrounded by an accretion gaseous disk with a magnetic field. The results of numerical simulations are compared with the observational data. The model of γ-ray gun permits in the framework of reasonable suppositions to obtain both high enough efficiency of line formation (10-4-10-3) and the required ratio between the intensity of γ-lines and continuous γ-spectrum in its vicinity. The observed sharp break (or even the maximum) near 2 MeV is explained in the framework of the model. γ-line and continuous spectrum variation can be explained by the changes both in the target and in the source