  Current phenomenology suggests the presence of a compact baryon-poor energy
source to cosmological gamma-ray bursts reacting to high-density matter. The
association of short and long gamma-ray bursts with hyper- and suspended
accretion onto slowly and rapidly spinning black holes predicts weak X-ray
afterglow emissions from short bursts, as in GRB050509B and GRB050709. Long
gamma-ray bursts are probably the birth place of rapidly spinning high-mass
black holes in core-collapse of massive stars, as in GRB030329 with supernova
SN2003dh. This predicts a long-duration burst of gravitational radiation
powered by the spin-energy of the black hole. In contrast to MeV-neutrino
emissions, as in SN1987A, this can be tested by the advanced detectors LIGO and
Virgo about once per year up to distances of about 100Mpc. Detection of the
expected chirps and long-duration bursts of gravitational waves promises
identification of Kerr black holes as the most luminous objects in the
Universe.
