Impact of higher derivative corrections to general relativity on black hole mergers

Abstract

The merging of two black holes is a notoriously difficult process to describe exactly. Nevertheless, the hindrances posed by gravity’s nonlinearity can be circumvented by focusing on the strict extreme mass ratio limit, in which one of the black holes is infinitely larger than the other. Such an approach has been developed by Emparan and Martínez and applied within general relativity to investigate the time evolution of event horizons melding, using nothing but elementary concepts in gravitational physics and simple integrations of geodesics. We apply this strategy to study black hole mergers in higher derivative gravity in order to assess how the defining characteristics of the fusion process change as the gravitational theory is modified. We adopt the case of Einsteinian cubic gravity for concreteness, and determine how the mergers’ duration and the relative area increment change as the theory’s single coupling parameter is varied.