gamma-ray burst

New insights into the behavior of rotating black holes could help unravel a 30-year-old cosmic mysterynamely, where those elusive deep-space explosions known as gamma-ray bursts come from. According to the scientists who conducted the research, the bursts could be one product of a kind of cosmic dance between a spinning black hole and its surrounding doughnut-shaped ring, or torus. When a rotating black hole starts spinning twice as fast as its torus, they propose, a beamlike burst of energy flows out along the rotational axis of the pair, culminating several billion miles away in an explosion of gamma rays. Maurice van Putten of the Massachusetts Institute of Technology and Amir Levinson of Tel Aviv University describe their new model in the current issue of the journal Science.

The scientists postulate that these beams actually emit only a tiny fraction of the total radiation. A typical spinning black hole--called a Kerr black hole, after the scientist who predicted its existence in 1963--stores a third of its mass in rotational energy, according to van Putten. In the teams model, the black hole transfers the majority of its spin energy to the torus, which then radiates most of the received energy as gravitational waves. This transfer of energy accounts for the unusually long--20-second--life span of the torus, the scientists say. Without gravitational wave radiation, the torus would either explode or be swallowed instantly.

Down the road, the investigators hope that the new Laser Interferometer Gravitational-wave Observatory (LIGO), scheduled to operate at full power by 2008, will detect gravitational waves. Such findings could provide the first cosmological proof of the existence of Kerr black holes.