Black Hole Hyperaccretion and Gamma-ray Burststwo

Black hole hyperaccretion model is one of the potential candidates for the central engine of gamma-ray bursts. Combined with the complicated explosion phenomena including gamma-ray bursts, gravitational waves, and their electromagnetic counterparts, the results of a series of theoretical studies on this model are briefly reviewed in this paper. At the same time, as the research tools for the subsequent studies on gamma-ray bursts, some important conclusions and formulas are presented.     

Hyperaccretion after the Blandford-Znajek Process： A New Model for GRBs with X-Ray Flares Observed in Early Afterglows

We propose a three-stage model with Blandford-Znajek (BZ) and hyperaccretion process to interpret the recent observations of early afterglows of Gamma-Ray Bursts (GRBs). In the first stage, the prompt GRB is powered by a rotating black hole (BH) invoking the BZ process. The second stage is a quiet stage, in which the BZ process is shut off, and the accretion onto the BH is depressed by the torque exerted by the magnetic coupling (MC) process. Part of the rotational energy transported by the MC process from the BH is stored in the disk as magnetic energy. In the third stage, the MC process is shut off when the magnetic energy in the disk accumulates and triggers magnetic instability. At this moment, the hyperaccretion process may set in, and the jet launched in this restarted central engine generates the observed X-ray flares. This model can account for the energies and timescales of GRBs with X-ray flares observed in early afterglows.