Stability, causality and quasinormal modes of cosmic strings and cylinders

TL;DR

This paper investigates the behavior of scalar fields in cylindrically symmetric spacetimes, revealing instability in rotating cosmic cylinders with closed time-like curves through quasinormal mode analysis.

Contribution

It provides the first calculation of quasinormal modes for rotating cosmic cylinders and links their stability to the presence of closed time-like curves.

Findings

Unstable modes found in some rotating cosmic cylinders.

Static and rotating cosmic strings without regular interiors lack quasinormal modes.

Rotating cosmic cylinders with closed time-like curves are unstable against scalar perturbations.

Abstract

In this work we consider the evolution of a massive scalar field in cylindrically symmetric space-times. Quasinormal modes have been calculated for static and rotating cosmic cylinders. We found unstable modes in some cases. Rotating as well as static cosmic strings, i.e., without regular interior solutions, do not display quasinormal oscillation modes. We conclude that rotating cosmic cylinder space-times that present closed time-like curves are unstable against scalar perturbations.