Ergoregions between two ergospheres

TL;DR

This paper investigates the properties of ergoregions with two boundary components in stationary spacetimes, extending previous work on simpler ergoregion geometries.

Contribution

It analyzes the structure and characteristics of annular ergoregions with two boundaries, expanding understanding beyond single-boundary ergoregions.

Findings

Characterization of ergoregions with two boundaries

Extension of existence and regularity results

Insights into ergoregion topology and geometry

Abstract

For a stationary spacetime metric, black holes are spatial regions which disturbances may not propagate out of. In our previous work an existence and regularity theorem was proven for black holes in two space dimensions, in the case where the boundary of the ergoregion is a simple closed curve surrounding a singularity. In this paper we study the case of an annular ergoregion, whose boundary has two components.