Toroidal Horizons in Binary Black Hole Mergers

Abstract

We find the first binary black hole event horizon with a toroidal topology. It had been predicted that generically the event horizons of merging black holes should briefly have a toroidal topology, but such a phase has never been seen prior to this work. In all previous binary black hole simulations, in the coordinate slicing used to evolve the black holes, the topology of the event horizon transitions directly from two spheres during the inspiral to a single sphere as the black holes merge. We present a coordinate transformation to a foliation of spacelike hypersurfaces that "cut a hole" through the event horizon surface, resulting in a toroidal event horizon. A torus could potentially provide a mechanism for violating topological censorship. However, these toroidal event horizons satisfy topological censorship by construction, because we can always trivially apply the inverse coordinate transformation to remove the topological feature.

13 pages, 18 figures, supplementary videos at https://www.black-holes.org/for-researchers/event-horizon-topologies

References in corpus (4)

• Observation of Gravitational Waves from a Binary Black Hole Merger
• Dynamical Excision Boundaries in Spectral Evolutions of Binary Black Hole Spacetimes
• Revisiting Event Horizon Finders
• Seeking for toroidal event horizons from initially stationary BH configurations

Cited by in corpus (8)

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• Topological regular black holes without Cauchy horizon
• Black hole shadow and Wandering null geodesics
• Deformation of horizons during a merger
• Precursory collapse in Neutron Star-Black Hole mergers
• The binary black hole explorer: on-the-fly visualizations of precessing binary black holes
• Marginally Outer Trapped Tori in Black Hole Spacetimes
• Microscopic State of BHs and an Exact One Body Method for Binary Dynamics in General Relativity