POSSIBLE EPISODIC GAMMA-RAY SOURCES

A model for production of episodic gamma-ray event at interaction of a moving gas target with a beam of relativistic particles is proposed. The typical duration of gamma-ray emission is limited by the flight ti me of the target across the beam as well as by the time of destruction and/or expulsion of the target by luminous beam. The time-dependent r adiation spectra of the expanding and moving gas cloud irradiated by t he beam are calculated for the galactic binary systems Her X-1 and AE Aquarii which are reported as episodic gamma-ray emitters at very high energies. Some predictions and observational tests for the model are discussed.