Event Horizon of a Charged Black Hole Binary Merger

TL;DR

This paper studies how charge affects the event horizon during black hole binary mergers, providing analytical and numerical insights relevant for gravitational wave observations and theories beyond general relativity.

Contribution

It offers new analytical and numerical analyses of charged black hole mergers, including horizon evolution and area growth, in various dimensions and limits.

Findings

Charge influences merger properties and horizon evolution.

Analytical results in the Extreme Mass Ratio limit are developed.

Numerical solutions are provided for arbitrary dimensions.

Abstract

We analyse the formation and evolution of the event horizon of a black hole binary merger when the black holes are charged. We find that the presence of charge influences the properties of the merger and can be useful for investigating the validity of various theories of modified gravity and several proposals for dark matter candidates. It can moreover give insights into various aspects of astrophysical phenomena involving black holes, such as degeneracies in the gravitational wave parameter determination. We perform our analysis both analytically and numerically, in $D=4$ dimensions, in the Extreme Mass Ratio (EMR) limit and compare the results. The development of analytical results in the EMR limit is of uttermost importance in view of the upcoming observations of the LISA interferometer. We then use our analysis to describe how the horizon evolves in time during the merger and to investigate the growth in the area of the event horizon and the duration of the merger. We moreover provide a numerical solution valid in arbitrary dimensions $D \geq 4$ which could be of interest in the context of the AdS/CFT correspondence or for examining possible extensions of general relativity.