Self-force as a cosmic censor

We examine Hubeny’s scenario according to which a near-extremal Reissner-Nordström black hole can absorb a charged particle and be driven toward an over-extremal state in which the charge exceeds the mass, signaling the destruction of the black hole. Our analysis incorporates the particle’s electromagnetic self-force and the energy radiated to infinity in the form of electromagnetic waves. With these essential ingredients, our sampling of the parameter space reveals no instances of an overcharged final state, and we conjecture that the self-force acts as a cosmic censor, preventing the destruction of a near-extremal black hole by the absorption of a charged particle. We argue, on the basis of the third law of black hole mechanics, that this conclusion is robust and should apply to attempts to overspin a Kerr black hole.

Figure 1

Plot of $r^2{f}^r$ as a function of $r/M$ for the first case listed in Table . The dashed line (blue) is the local approximation. The solid line (red) is the result of our computation. The local approximation overestimates the self-force except when the particle is very close to the event horizon, where its action is most important. The oscillations seen below $r/M=5$ are a manifestation of numerical noise associated with an unphysical burst of radiation taking place at $t=0$.