Dynamics of black holes in de Sitter spacetimes

TL;DR

This paper investigates the nonlinear dynamics of black holes in de Sitter spacetimes, comparing analytical, perturbative, and numerical methods to understand mergers, scattering, and cosmic censorship in an expanding universe.

Contribution

It provides the first comparison of analytical, perturbative, and nonlinear simulations for black hole collisions in de Sitter backgrounds.

Findings

Accurate determination of merger/scatter transition for small binaries

Test of the Cosmic Censorship conjecture for large binaries

Black holes in large binaries lose causal contact, supporting the conjecture

Abstract

Nonlinear dynamics in cosmological backgrounds has the potential to teach us immensely about our universe, and also to serve as prototype for nonlinear processes in generic curved spacetimes. Here we report on dynamical evolutions of black holes in asymptotically de Sitter spacetimes. We focus on the head-on collision of equal mass binaries and for the first time compare analytical and perturbative methods with full blown nonlinear simulations. Our results include an accurate determination of the merger/scatter transition (consequence of an expanding background) for small mass binaries and a test of the Cosmic Censorship conjecture, for large mass binaries. We observe that, even starting from small separations, black holes in large mass binaries eventually lose causal contact, in agreement with the conjecture.