Black holes in self-tuning cubic Horndeski cosmology

TL;DR

This paper constructs and analyzes black hole solutions in a restricted scalar-tensor theory with self-tuning properties, revealing unique horizon structures and scalar hair that differ from standard general relativity.

Contribution

It introduces explicit black hole solutions within the self-tuning cubic Horndeski framework, demonstrating how the scalar field absorbs the cosmological constant and affects black hole geometry.

Findings

Black holes exhibit scalar hair due to scalar field velocity.

Solutions asymptote to self-tuned de Sitter space.

Near-horizon geometry differs from standard GR black holes.

Abstract

Observations of neutron star mergers in the late Universe have given significant restrictions to the class of viable scalar-tensor theories. In this paper we construct black holes within the "self-tuning" class of this restricted set, whereby the bare cosmological constant is absorbed by the dynamics of the scalar, giving a lower effective cosmological constant. We use analytic expansions at the singularity, black hole and cosmological horizon, and asymptotic region, coupled with numerical solutions, to find well-behaved black holes that asymptote to the self-tuned de Sitter geometry. The geometry differs from standard general relativity black holes near the horizon, and the scalar field velocity provides a hair for the black holes.