Escape probability of the super-Penrose process

TL;DR

This paper analyzes the escape probability and energy of massless particles produced in head-on collisions near an extremal Kerr black hole's horizon, revealing conditions for arbitrarily high energy escape.

Contribution

It provides a detailed calculation of the escape probability and energy distribution of particles resulting from collisions near an extremal Kerr black hole.

Findings

Escape probability approaches 5/12 for isotropic emission in the equatorial plane.

Produced particles can escape with arbitrarily large energy near the horizon.

Most escaping particles have impact parameters close to 2GM/c^2.

Abstract

We consider a head-on collision of two massive particles that move in the equatorial plane of an extremal Kerr black hole, which results in the production of two massless particles. Focusing on a typical case, where both of the colliding particles have zero angular momenta, we show that a massless particle produced in such a collision can escape to infinity with arbitrarily large energy in the near-horizon limit of the collision point. Furthermore, if we assume that the emission of the produced massless particles is isotropic in the center-of-mass frame but confined to the equatorial plane, the escape probability of the produced massless particle approaches $5/12$ and almost all escaping massless particles have arbitrarily large energy at infinity and an impact parameter approaching $2GM/c^2$, where $M$ is the mass of the black hole.