Scalar Lumps with Two Horizons

TL;DR

This paper explores new static, spherically symmetric solutions with scalar fields and two horizons, including novel configurations where scalar lumps alter horizon structures, relevant for black hole physics and vacuum decay.

Contribution

It introduces a new class of solutions where scalar lumps significantly modify horizon properties, expanding understanding of scalar field effects in gravitational settings.

Findings

Discovery of solutions with scalar lumps between two horizons.

Identification of solutions where scalar fields turn cosmological horizons into trapped horizons.

Potential implications for black hole seeded vacuum decay.

Abstract

We study generalisations of the Schwarzschild-de Sitter solution in the presence of a scalar field with a potential barrier. These static, spherically symmetric solutions have two horizons, in between which the scalar interpolates at least once across the potential barrier, thus developing a lump. In part, we recover solutions discussed earlier in the literature and for those we clarify their properties. But we also find a new class of solutions in which the scalar lump curves the spacetime sufficiently strongly so as to change the nature of the erstwhile cosmological horizon into an additional trapped horizon, resulting in a scalar lump surrounded by two black holes. These new solutions appear in a wide range of the parameter space of the potential. We also discuss (challenges for) the application of all of these solutions to black hole seeded vacuum decay.