COLLAPSE OF A DIFFERENTIALLY ROTATING SUPERMASSIVE STAR TO A SUPERMASSIVE BLACK HOLE

摘要

We investigate the collapse of differentially rotating supermassive stars by means of 3+1 hydrodynamic simulations in general relativity. We particularly focus on the formation of a rapidly rotating dynamic black hole, and find the following two features. Firstly, quasi-periodic gravitational waves continue to be emitted after the quasi-normal mode frequency has decayed. Secondly, when the newly formed black hole is almost extreme Kerr, the amplitude of the quasi-periodic oscillation is enhanced during the late stages of the evolution. Geometrical features, shock waves, and instabilities of the fluid are suggested as a cause of this amplification behaviour. This alternative scenario for the collapse of differentially rotating supermassive stars might be observable by LISA.