Gamma-ray bursts (GRBs) are probably produced by black hole-disk/torus systems representing magnetized collapsars. We analyze the evolution of these states in response to large-scale magnetic torques. The disk accretion time-scale is of order tffEk/EB, where tff is the initial free fall time and Ek/EB is the ratio of kinetic-to-poloidalmagnetic energy. For a slowly-spinning black hole, unimpeded hyperaccetion prevails. For a rapidly spinning black hole, magnetic torques from the black hole arrest the inflow and suspend accretion, also driving a baryonic wind from the torus. We identify long/short GRBs with rapidly/slowly spinning black hole systems. HETE-II may detect afterglows from both short and long GRBs, but afterglow line-emission only from long GRBs. Subject headings: Gamma-ray bursts: collapsars, black hole-torus stat
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