Collisional Penrose process in Kerr–Taub–NUT spacetime

Abstract

Maximum efficiency of collisional Penrose process with spinning and non-spinning particles in Kerr–Taub–NUT spacetime has been studied. We consider three cases in detail: two massive particles collide near the horizon, one of the resulting massive particles escapes to infinity, and the other massive particle falls into the black hole; a massless particle collides with a massive particle, then the massless daughter particle escapes from the black hole to infinity, and the massive daughter particle falls into the black hole (Compton scattering); a massive particle collides with a massless particle, the massive daughter particle escapes from the black hole to infinity and the massless daughter particle falling into the horizon (inverse Compton scattering). We find that for these cases, regardless of whether particles are spinning or not, the maximum energy extraction efficiency of the collisional Penrose process always decreases as the NUT charge increases, and the energy extraction efficiency in the spinning case is always higher than that in the non-spinning case.