Rotating non-Kerr black hole and energy extraction

TL;DR

This paper studies how a deformation parameter affects the ergosphere and energy extraction efficiency in rotating non-Kerr black holes, revealing enhanced energy extraction potential compared to Kerr black holes.

Contribution

It introduces analysis of the ergosphere shape and energy extraction efficiency in non-Kerr black holes with a deformation parameter, highlighting significant differences from Kerr black holes.

Findings

Deformation parameter $$ enlarges the ergosphere.

Energy extraction efficiency can exceed 60% for superspinning non-Kerr black holes.

Efficiency is significantly higher than in Kerr black holes, which is only 20.7%.

Abstract

The properties of the ergosphere and energy extraction by Penrose process in a rotating non-Kerr black hole are investigated. It is shown that the ergosphere is sensitive to the deformation parameter $\epsilon$ and the shape of the ergosphere becomes thick with increase of the parameter $\epsilon$. It is of interest to note that, comparing with the Kerr black hole, the deformation parameter $\epsilon$ can enhance the maximum efficiency of the energy extraction process greatly. Especially, for the case of $a>M$, the non-Kerr metric describes a superspinning compact object and the maximum efficiency can exceed 60%, while it is only 20.7% for the extremal Kerr black hole.