Black bounces to traversable wormholes from pure gravity in four and higher dimensions

Abstract

This article derives static and spherically symmetric wormhole and black bounce spacetimes as vacuum solutions of metric gravitational theories in four and higher dimensions. To this end, I extend previous results on quasi-topological gravities to encompass cases in which the metric depends on two arbitrary functions of one variable --- instead of the usual single function. I then explain how, given (almost) any spherically symmetric metric, one can reverse engineer a well-defined higher-dimensional theory having such a metric as solution. I apply these results to three paradigmatic examples, including the Simpson--Visser black bounce, to showcase the versatility of this method, as well as its limitations. Moreover, I consider the coupling to a Vaidya-like matter source, so as to generate time-varying solutions and investigate what kind of dynamical evolution these theories can account for.