Stellar collapse with pressure in effective loop quantum gravity

TL;DR

This paper investigates how pressure affects stellar collapse in effective loop quantum gravity, showing that quantum effects replace classical singularities with bounces, but shell-crossing singularities persist regardless of pressure.

Contribution

It generalizes semiclassical dust collapse models to include pressure and analyzes the impact on singularity formation and spacetime structure in loop quantum gravity.

Findings

Shell-focusing singularities are resolved by quantum effects, replaced by a bounce.

Shell-crossing singularities remain a feature even with pressure.

Inclusion of pressure does not change the qualitative collapse behavior.

Abstract

We explore semiclassical stellar collapse scenarios with pressure within the framework of effective loop quantum gravity. The objective of this work is to generalize existent models of semiclassical dust collapse and examine the role of pressure in the formation of shell-crossing singularities in a semiclassical context. Numerical investigations show that the shell-focusing singularity characterizing the end state of any classical stellar collapse is here resolved by quantum gravitational effects and replaced by a bounce of the star. However, they also show that shell-crossing singularities remain a general feature of these models and that the inclusion of pressure does not alter the qualitative picture emerging from semiclassical models of inhomogeneous dust collapse. Given the absence of a shell-focusing singularity and the possibility of extending spacetime in the future of the trapped region formed by gravitational collapse, the investigation of the causal structure of the spacetime describing the semiclassical collapse of a star is inevitably tied to a better understanding of the physics of these shell-crossing singularities.