Gravitational radiation from gamma-ray burst-supernovae as observational opportunities for LIGO and VIRGO

Gamma-ray bursts are believed to originate in the core collapse of massive stars. This produces an active MeV-nucleus containing a rapidly rotating Kerr black hole of mass MH and angular velocity ΩH1/2MH, surrounded by a uniformly magnetized torus of angular velocity ΩT=ηΩH represented by two counteroriented current rings. We quantify black-hole--spin interactions with the torus and charged particles along open magnetic flux tubes subtended by the event horizon at a finite half-opening angle θH. A major output of Egw4×10⁵³(η/0.1)(MH/7M_)erg is radiated in gravitational waves of frequency fgw500(η/0.1)(7M_/MH) Hz by a quadrupole mass moment in the torus when its minor-to-major radius is less than 0.3260. The durations correspond to the lifetime Tₛ of black hole spin, determined by a stability condition of poloidal magnetic field energy-to-kinetic energy $<1/15$ in the torus. Consistent with observations of GRB-SNe, we find (i) Tₛ90s (tens of s), (ii) aspherical SNe of kinetic energy ESN2×10⁵¹erg (2×10⁵¹erg in SN1998bw), and (iii) GRB-energies E_γ2×10⁵⁰erg(3×10⁵⁰erg), upon associating θH with poloidal curvature of the magnetosphere. GRB-SNe occur perhaps about once a year within D=100Mpc. Correlating LIGO-VIRGO detectors enables searches for nearby events and their spectral closure density 6×10^-9 around 250 Hz in the stochastic background radiation in gravitational waves. At current sensitivity, LIGO-Hanford may place an upper bound around 150M_ in GRB030329. Upcoming all-sky supernovae surveys may provide distances to GRB-SNe, conceivably coincident with weak wide-angle GRB emissions similar to the nearby event GRB980425/SN1998bw. Detection of Egw thus provides a method for identifying Kerr black holes by calorimetry.