Black Bounces with multiple throats and anti-throats

TL;DR

This paper explores new black-bounce spacetimes with complex structures like anti-throats, analyzing their geometric properties, energy conditions, and potential for regular extensions within four-dimensional general relativity.

Contribution

It introduces novel black-bounce metrics with multiple throats and anti-throats, examining their regularity, symmetry, and energy condition compliance, including models satisfying the null energy condition outside the horizon.

Findings

Some models have curvature singularities at infinity regions.

Regular metrics can be extended to negative radial coordinates.

Certain models satisfy the null energy condition outside the horizon.

Abstract

In this article, we test the possibility of building new black-bounce spacetimes with changes in the area in the context of general relativity in four dimensions. These new metrics can present extra structures, such as anti-throats. We see two regions where the area goes to infinity, and, depending on the model, one of these regions presents curvature singularities. Regular metrics can be extended to negative values of the radial coordinate and have a symmetrical structure, whereas some singular cases cannot be extended and have no symmetrical structure. The energy conditions are analyzed, and, for some cases, at least one of the inequalities in the null energy condition is not respected. We also presented models that satisfied the null energy condition outside the event horizon. The event horizon hides the throats of these models.