Black Hole Formation with an Interacting Vacuum Energy Density

TL;DR

This paper investigates how an interacting vacuum energy density affects the gravitational collapse of a star's core, revealing that while it delays collapse, it does not prevent singularity formation and influences the singularity's nature.

Contribution

It introduces a phenomenological eta-parameter to model vacuum-fluid interaction effects on gravitational collapse, analyzing the conditions for different singularity outcomes.

Findings

Vacuum energy increases collapse time.

Collapse still leads to singularity for all eta values.

Nature of singularity depends on eta and fluid equation of state.

Abstract

We discuss the gravitational collapse of a spherically symmetric massive core of a star in which the fluid component is interacting with a growing vacuum energy density. The influence of the variable vacuum in the collapsing core is quantified by a phenomenological \beta-parameter as predicted by dimensional arguments and the renormalization group approach. For all reasonable values of this free parameter, we find that the vacuum energy density increases the collapsing time but it cannot prevent the formation of a singular point. However, the nature of the singularity depends on the values of \beta. In the radiation case, a trapped surface is formed for \beta<1/2 whereas for \beta>1/2, a naked singularity is developed. In general, the critical value is \beta=1-2/3(1+\omega), where the \omega-parameter describes the equation of state of the fluid component.