TP-02
We suggest that an extreme Kerr black hole with a mass , a dimensionless angular momentum and a marginal stable orbital radius located in a normal galaxy, may produced a GRB by capturing and disrupting a star. During this period, a transient accretion disk is formed and a strong transient magnetic field Gauss, lasting for , may be produced in the inner boundary of the accretion disk. A large amount of rotational energy of the black hole is extracted and released in the ultra relativistic jet with a bulk Lorentz factor larger than 103 via Blandford-Znajek process. The relativistic jet energy can be converted into -ray radiation via internal shock mechanism. The gamma-ray burst (GRB) duration should be the same as that of the life time of the strong transient magnetic field. The maximum number of sub-bursts is estimated to be because the disk material is likely broken into pieces with the size about the thickness of the disk h at the cusp ( ). The shortest rising time of the burst estimated from this model is s. The model gamma-ray burst density rate is also estimated.
Fifth Huntsville Gamma Ray Burst Symposium
Hunsville, Alabama, USA
18-22 October, 1999