Gamma-ray bursts: Ligo/virgo sources of gravitational radiation

The status and prospects are reviewed for the presently most favored model for the inner engine of cosmological gamma-ray bursts (GRBs): the black hol e-torus model. Support for this model is derived from recent GRB-phenomenol ogy: a cosmological origin, a bi-modal distribution in their durations, and potentially a GRB/X-ray transient connection. The black hole-torus model o perates by the rotation of the central Kerr black hole, which introduces tw o new mechanisms: in-situ pair-creation on open field-lines along the axis of rotation and a powerful magnetic black hole-to-torus coupling. The lepto nic winds serve as input to the GRB-afterglow emissions. Long/short GRBs ar e identified with suspended/hyper-accretion onto rapidly/slowly rotating bl ack holes. The suspended accretion state is expected to be accompanied by b aryonic winds blown off the torus; if formed in stellar collapse, these win ds may account for recently detected iron line-emissions and may have contr ibuted to the chemical abundances in X-ray transients. This implies that ME TE-II will detect afterglows from all bursts, but iron-line emission only f rom long bursts. In long bursts, the tents is expected to radiate most of t he black hole luminosity in gravitational waves. This predicts that long GR Bs are potentially the most powerful burst-sources of gravitational waves i n the Universe. Their emissions trace a horizontal branch in the f(f)-diagr am, which can be tested by LIGO/VIRGO. (C) 2001 Published by Elsevier Scien ce B.V.