Ultra-high energy collisions of nonequatorial geodesic particles near dirty black holes

TL;DR

This paper demonstrates that ultra-high energy collisions, known as the BSW effect, can occur near the horizons of generic rotating black holes for any particle motion, extending previous specific cases.

Contribution

It generalizes the BSW effect to arbitrary nonequatorial motion around generic rotating black holes without relying on special symmetries.

Findings

The BSW effect occurs near any point of the horizon surface.

The results are applicable to a broad class of rotating black holes, not just Kerr.

The paper provides a general classification scheme for collision scenarios.

Abstract

We consider collision of two geodesic particles moving around rotating stationary axially symmetric black holes. It is shown for arbitrary nonequatorial motion that under certain conditions the energy in their centre of mass frame can grow unbound (the so-called BSW effect). This generalizes the previous results for equatorial motion around dirty (surrounded by matter) black holes and nonequatorial motion around the Kerr metric. It turns out that the BSW effect occurs near any point of the horizon surface. We do not use special symmetries of space-time typical of the Kerr metric, so the results are quite generic. The general scheme classifying all possible scenarios is discussed.