Can soft γ-ray bursts be emitted by accreting black holes?

THERE are many models for the observed γ-ray bursts¹, but none has proved entirely satisfactory. Here we suggest another possible model: that the γ rays are produced by inverse Compton processes occurring deep in the ergosphere of a fast rotating, accreting, black hole. At the time of burst, plasma, which has an optical depth of the order of the relevant gravitational distances, emerges near the horizon due to an instability, and free falling photons, which are produced by viscous processes in an accretion disk further away, are being scattered off it. In this model the black hole itself is probably a member of a binary system, and, depending on its steady-state accretion rate, may or may not be observable as an X-ray source.