摘要

A new model for gamma-ray bursts (GRBs) is discussed by considering the coexistence of the Blandford-Znajek (BZ) process and the magnetic coupling (MC) process, in which the half-open angle theta(BZ) of the open magnetic flux on the horizon is determined by the mapping relation between the angular coordinate on the horizon and the radial coordinate on the disk with the assumption that the closed magnetic flux penetrating the disk takes precedence over the open magnetic flux. The GRB is powered by the BZ process with the duration identified as the lifetime of open magnetic flux on the horizon. The powers and torques of the BZ and MC processes are derived by using an improved equivalent circuit. It is shown that the BH is slowed down strongly by the MC process, resulting in a greater average power than other models for GRBs powered by the BZ process. It turns out that the data of several GRBs are well fitted by our model.