Disformal Transition of a Black Hole to a Wormhole in Scalar-Tensor Horndeski Theory

TL;DR

This paper demonstrates how disformal transformations in a specific scalar-tensor theory can convert a hairy black hole into a wormhole, violating energy conditions and analyzing the stability of the resulting wormhole.

Contribution

It introduces a novel disformal transformation approach to transition black holes into wormholes within Horndeski theory, including stability analysis.

Findings

Black hole to wormhole transition via disformal transformation

Null energy condition violation in the wormhole configuration

Stability of the wormhole under scalar perturbations

Abstract

We consider disformal transformations in a subclass of Horndeski theory in which a scalar field is kinetically coupled to the Einstein tensor. We apply a disformal transformation on a seed hairy black hole solution of this theory and we show that there is a transition of a black hole to a wormhole. We also show that the null energy condition is violated in the wormhole configuration and we study the stability of the wormhole solution by calculating the time evolution of scalar perturbations in this geometry.