LIGO/VIRGO searches for gravitational radiation in hypernovae
  A torus around a stellar mass Kerr black hole can emit about 10% of the spin-energy of the black hole in gravitational radiation, potentially associated with a gamma-ray burst. Wide tori may develop buckling modes by the Papaloizou-Pringle instability and gravitational radiation-reaction forces in the Burke-Thorne approximation. Gravitational wave experiments may discover these emissions in a fraction of nearby supernovae. This provides a test for Kerr black holes, and for GRB inner engines by comparison with the de-redshifted durations of long GRBs. 
Maurice H.P.M. van Putten