A calorimetric test for Kerr black holes in gamma-ray bursts

Cosmological gamma-ray bursts are potentially associated with systems harboring a rotating black hole. Calorimetry on yet "unseen" emissions in gravitational waves from a surrounding torus may provide a measure for its rotational energy. We introduce a compactness parameter alpha = 2 pi integralf dE for the fluence E and frequency f in gravitational waves. For black hole-torus systems, alpha similar or equal to 2 pi Ef similar or equal to 0.005-0.05 may exceed the upper bound alpha = 0.005 for rapidly rotating neutron stars. A duration in gravitational radiation consistent with the redshift-corrected durations of the BATSE catalog defines an association with long gamma-ray bursts. This promises to be a new test for Kerr black holes as objects in nature.