New 2D dilaton gravity for nonsingular black holes

TL;DR

This paper introduces a new two-dimensional gravity model extending spherically symmetric Einstein-Lanczos-Lovelock gravity, enabling nonsingular black hole solutions with second-order field equations and Birkhoff's theorem.

Contribution

It develops a novel 2D action with arbitrary functions that generalizes existing models, allowing for a broader class of nonsingular black hole solutions.

Findings

Second-order field equations with Birkhoff's theorem

Generalized Misner-Sharp mass as a first integral

Vacuum solutions include new nonsingular black holes

Abstract

We construct a two-dimensional action that is an extension of spherically symmetric Einstein-Lanczos-Lovelock gravity. The action contains arbitrary functions of the areal radius and the norm squared of its gradient, but the field equations are second order and obey Birkhoff's theorem. In complete analogy with spherically symmetric Einstein-Lanczos-Lovelock gravity, the field equations admit the generalized Misner-Sharp mass as the first integral that determines the form of the vacuum solution. The arbitrary functions in the action allow for vacuum solutions that describe a larger class of interesting nonsingular black-hole spacetimes than previously available.