Proposed gravitational wave background from black hole-torus systems
  Cosmological gamma-ray bursts may be powered by rotating black holes with contemporaneous emission of gravitational radiation from a surrounding torus. We calculate the resulting stochastic background radiation assuming strong cosmological evolution and a uniform black hole mass distribution of M= (4--14)M_odot. The predicted spectral flux density corresponds to a peak spectral closure density of (1--2) times 10^{-7}, and has comparable contributions at 450 Hz times kappa and over 300--450 Hz times kappa from nearby and distant sources, respectively, where kappa refers to an uncertainty factor of order unity in the radius of the torus. For two optimized advanced LIGO-type detectors the proposed gravitational wave background could be detectable within a year of integration. 
David M. Coward (UWA), Maurice H.P.M. van Putten (MIT), and Ronald R.   Burman (UWA)