The 1+1+2 formalism for Scalar-Tensor gravity

TL;DR

This paper applies the 1+1+2 covariant formalism to scalar-tensor gravity, clarifying spherically symmetric solutions, extending Birkhoff's theorem, and analyzing quasi-local horizons in non-minimally coupled theories.

Contribution

It introduces the 1+1+2 formalism to better understand spherically symmetric solutions in scalar-tensor gravity, extending classical results like Birkhoff's theorem.

Findings

Extended Birkhoff's theorem in scalar-tensor theories

Characterized quasi-local horizons in this context

Clarified properties of spherically symmetric solutions

Abstract

We use the 1+1+2 covariant approach to clarify a number of aspects of spherically symmetric solutions of non-minimally coupled scalar tensor theories. Particular attention is focused on the extension of Birkhoff's theorem and the nature of quasi-local horizons in this context.