Null limits of the C-metric

TL;DR

This paper investigates the null limit of the C-metric, revealing that it describes impulsive gravitational waves caused by cosmic strings snapping or expanding, thus connecting accelerating black hole solutions to wave phenomena.

Contribution

It provides a comprehensive analysis of the null limit of the C-metric, linking accelerating black hole solutions to impulsive gravitational waves from cosmic strings.

Findings

Null limit leads to impulsive gravitational waves

Spherical waves generated by cosmic strings

Connects black hole acceleration to wave phenomena

Abstract

The C-metric is usually understood as describing two black holes which accelerate in opposite directions under the action of some conical singularity. Here, we examine all the solutions of this type which represent accelerating sources and investigate the null limit in which the accelerations become unbounded. We show that the resulting space-times represent spherical impulsive gravitational waves generated by snapping or expanding cosmic strings.