Floating Orbits, Superradiant Scattering and the Black-hole Bomb

Abstract

Penrose¹ and Christodoulou² have shown how, in principle, rotational energy can be extracted from a black hole by orbiting and fissioning particles. Recently, Misner³ has pointed out that waves can also extract rotational energy (“superradiant scattering” in which an impinging wave is amplified as it scatters off a rotating hole). As one application of super-radiant scattering, Misner has suggested the possible existence of “floating orbits”, that is, orbits in which a particle radiatively extracts energy from the hole at the same rate as it radiates energy to infinity; thereby it experiences zero net radiation reaction.