Dynamical interiors of Black-Bounce spacetimes

TL;DR

This paper constructs regular dynamical interior models for black-bounce spacetimes, analyzes the matching conditions with the exterior, and explores the formation of horizons and physical implications of the regularization.

Contribution

It introduces a class of regular dynamical interiors for black-bounce spacetimes and examines the matching conditions and horizon formation within this framework.

Findings

Smooth matching with the exterior is not possible without a thin shell.

Derived expressions for energy density and pressure of the thin shell.

Discussed horizon formation during collapse scenarios.

Abstract

Using the Israel-Darmois junction conditions, we obtain a class of regular dynamical interiors to the recently proposed black-bounce spacetimes which regularises the Schwarzschild singularity by introducing a regularisation parameter. We show that a regularised Friedmann-Lemaitre-Robertson-Walker like interior geometry can not be matched smoothly with the exterior black-bounce spacetime through a timelike hypersurface, as there always exists a thin shell of non-zero energy-momentum tensor at the matching hypersurface. We obtain the expressions for the energy density and pressure of the thin shell energy-momentum tensor in terms of the regularisation parameter and derive an evolution equation for the scale factor of the interior geometry by imposing physical conditions on these components of the surface energy-momentum tensor. We also discuss the formation of the event horizon inside the interior in the case when the initial conditions are such that the situation describes a collapsing matter cloud. We elaborate upon the physical implications of these results.