Gravitational Collapse of a Rotating Cylindrical Null Shell in the Cosmic String Spacetime

TL;DR

This paper investigates the gravitational collapse of a rotating cylindrical null shell in a cosmic string spacetime, identifying a critical radius where the shell's energy density becomes zero or negative, indicating physical limits of the model.

Contribution

It introduces a model for rotating cylindrical null shell collapse in cosmic string spacetime and analyzes the conditions for physical viability based on energy density behavior.

Findings

Existence of a critical radius where energy density vanishes

Energy density becomes negative beyond the critical radius

Matching conditions become unphysical when shell exceeds critical radius

Abstract

We study the gravitational collapse of a rotating cylindrical null shell with flat interior and the metric of a spinning cosmic string as the exterior. We see that there is a critical radius, where the energy density of the shell vanishes and beyond which it would be negative, thereby signaling that the matching would be unphysical.