Time dependent black holes and scalar hair

TL;DR

This paper develops a method to accurately model scalar field accretion onto black holes in dark energy scenarios, providing exact solutions and analyzing the back reaction on black hole expansion.

Contribution

It introduces a consistent slow roll expansion approach and derives an exact scalar field solution regular at horizons, advancing understanding of black hole scalar hair and accretion.

Findings

Exact scalar field solution regular at horizons

Black hole expansion due to scalar back reaction quantified

Results independent of horizon size ratio

Abstract

We show how to correctly account for scalar accretion onto black holes in scalar field models of dark energy by a consistent expansion in terms of a slow roll parameter. We find an exact solution for the scalar field within our Hubble volume which is regular on both black hole and cosmological event horizons, and compute the back reaction of the scalar on the black hole, calculating the resulting expansion of the black hole. Our results are independent of the relative size of black hole and cosmological event horizons. We comment on the implications for more general black hole accretion, and the no hair theorems.