High energy collisions of particles inside ergosphere: general approach

TL;DR

This paper generalizes the understanding of high-energy particle collisions within the ergosphere of rotating black holes, demonstrating that such collisions can lead to unbounded energy growth under specific conditions, extending prior findings.

Contribution

It provides a general framework for analyzing particle collisions in ergospheres of rotating axially symmetric spacetimes, explaining the critical role of the ergosphere in energy amplification.

Findings

Energy in the center of mass frame can grow indefinitely during collisions in the ergosphere.

Negative angular momentum of one particle is essential for unbounded energy growth.

The general approach confirms previous specific results for Kerr black holes.

Abstract

We show that recent observation made in Grib and Pavlov, Europhys. Lett. 101 (2013) 20004 for the Kerr black hole is valid in the general case of rotating axially symmetric metric. Namely, collision of two particles in the ergosphere leads to indefinite growth of the energy in the centre of mass frame, provided the angular momentum of one of two particles is negative and increases without limit for a fixed energy at infinity. General approach enabled us to elucidate, why the role of the ergosphere in this process is crucial.