Confined Penrose process and black-hole bomb
arXiv:2204.12405 · doi:10.1103/PhysRevD.106.024037
Abstract
We consider the decay of a particle with some energy inside the ergosphere of a black hole. After the first decay one of particles with the energy falls towards a black hole while the second one with moves in the outward direction. It bounces back from a reflecting shell and, afterwards, the process repeats. For radial motion of charged particles in the Reissner-Nordstöm metric, the result depends strongly on a concrete scenario. In particular, an indefinitely large growth of energy inside a shell is possible that gives rise to a black-hole bomb. We also consider a similar multiple process with neutral particles in the background of a rotating axially symmetric stationary black hole. We demonstrate that, if particle decay occurs in the turning point, a black-hole bomb in this case is impossible at all. For a generic point inside the ergoregion, there is a condition for a black-hole bomb to exist. It relates the ratio of masses before and after decay and the velocity of a fragment in the center of mass frame.
16 pages. Presentation improved and slightly expanded, typos corrected. Matches published version