Gamma-ray Bursts and Gravitational Radiation from Black Hole-torus Systems

Cosmological gamma-ray bursts (GRBs) are probably powered by systems harboring a rotating black hole. This may result from hypernovae or black hole-neutron star coalescence. We identify short/long bursts with hyper-and suspended-accretion states around slowly/rapidly rotating black holes [van Putten & Ostriker, ApJL, 552, L31, 2001]. Black holes may be activated into producing outflows by a surrounding torus magnetosphere, in the form of baryon poor jets as input to the observed GRB/afterglow emissions. Here, we attribute these outflows to a differentially rotating gap in an open flux-tube along the axis of rotation of the black hole [van Putten, Phys. Rep., 345, 1 (2001)]. A high incidence of the black hole luminosity into the surrounding matter is expected by equivalence in poloidal topology to pulsar magnetospheres. For long bursts, this predicts a large fraction of the black hole spin-energy emitted in gravitational waves by a quadrupole moment in the surrounding torus [van Putten & Levinson, ApJL, 555, L41, 2001]. This suggests that long GRBs may be the most powerful LIGO/VIRGO burst sources of gravitational waves in the Universe with an expected duration of 10-15s on a horizontal branch of 1-2kHz in the ˙ f (f)−diagram [van Putten, Phys. Rev. Lett., 87, 091101, 2001]. Gravitational wave-emissions from GRBs, therefore, promise calorimetric evidence for Kerr black holes.