An AdS Crunch in Supergravity

TL;DR

This paper explores modified boundary conditions in N=8 gauged supergravity, revealing black hole solutions with scalar hair, non-uniqueness of black holes, and the potential for dual CFT descriptions of cosmological singularities.

Contribution

It introduces a new class of boundary conditions preserving AdS symmetry, demonstrating black hole non-uniqueness and solutions evolving to big crunch singularities in supergravity.

Findings

Existence of black holes with scalar hair under new boundary conditions.

Black hole solutions are not unique, including Schwarzschild-AdS.

Solutions can evolve from smooth initial data to a big crunch singularity.

Abstract

We review some properties of N=8 gauged supergravity in four dimensions with modified, but AdS invariant boundary conditions on the m^2=-2 scalars. There is a one-parameter class of asymptotic conditions on these fields and the metric components, for which the full AdS symmetry group is preserved. The generators of the asymptotic symmetries are finite, but acquire a contribution from the scalar fields. For a large class of such boundary conditions, we find there exist black holes with scalar hair that are specified by a single conserved charge. Since Schwarschild-AdS is a solution too for all boundary conditions, this provides an example of black hole non-uniqueness. We also show there exist solutions where smooth initial data evolve to a big crunch singularity. This opens up the possibility of using the dual conformal field theory to obtain a fully quantum description of the cosmological singularity, and we report on a preliminary study of this.