Black holes in scalar-tensor gravity

TL;DR

This paper extends Hawking's no-hair theorem to a broad class of scalar-tensor and f(R) gravity theories, showing that stationary black holes are indistinguishable from those in general relativity.

Contribution

It generalizes the no-hair theorem to scalar-tensor and f(R) gravity theories without symmetry assumptions.

Findings

Stationary black holes in these theories are equivalent to those in general relativity.

The proof does not rely on symmetry assumptions.

The result broadens understanding of black hole solutions in alternative gravity theories.

Abstract

Hawking has proven that black holes which are stationary as the endpoint of gravitational collapse in Brans--Dicke theory (without a potential) are no different than in general relativity. We extend this proof to the much more general class of scalar-tensor and f(R) gravity theories, without assuming any symmetries apart from stationarity.