New Charged Black Holes with Conformal Scalar Hair

TL;DR

This paper constructs a new class of four-dimensional charged black holes with conformal scalar hair, extending known solutions and removing conical singularities through scalar field back reaction.

Contribution

It introduces a novel family of hairy black hole solutions within the Einstein-Maxwell-Lambda system, including their static limits and regularity properties.

Findings

New hairy black hole solutions with scalar hair and charge.

Scalar field back reaction removes conical singularities.

Solutions include limits to known black holes like Bekenstein and Martinez-Troncoso-Zanelli.

Abstract

A new class of four-dimensional, hairy, stationary solutions of the Einstein-Maxwell-Lambda system with a conformally coupled scalar field is constructed in this paper. The metric belongs to the Plebanski-Demianski family and hence its static limit has the form of the charged C-metric. It is shown that, in the static case, a new family of hairy black holes arises. They turn out to be cohomogeneity-two, with horizons that are neither Einstein nor homogenous manifolds. The conical singularities in the C-metric can be removed due to the back reaction of the scalar field providing a new kind of regular, radiative spacetime. The scalar field carries a continuous parameter proportional to the usual acceleration present in the C-metric. In the zero-acceleration limit, the static solution reduces to the dyonic Bocharova-Bronnikov-Melnikov-Bekenstein solution or the dyonic extension of the Martinez-Troncoso-Zanelli black holes, depending on the value of the cosmological constant.