Perturbations of Spacetime around a Stationary Rotating Cosmic String

TL;DR

This paper analyzes the spacetime perturbations caused by a stationary rotating cosmic string, revealing effects like frame-dragging, gravitational potential, and gravitational wave emission with direction-dependent waveforms.

Contribution

It provides a detailed solution to linearized Einstein equations around a rotating cosmic string, including gravitational wave emission and directional dependence of waveforms.

Findings

Frame-dragging effects around the string

Gravitational wave emission at discrete angles

Explicit waveforms and polarizations

Abstract

We consider the metric perturbations around a stationary rotating Nambu-Goto string in Minkowski spacetime. By solving the linearized Einstein equations, we study the effects of azimuthal frame-dragging around the rotation axis and linear frame-dragging along the rotation axis, the Newtonian logarithmic potential, and the angular deficit around the string as the potential mode. We also investigate gravitational waves propagating off the string and propagating along the string, and show that the stationary rotating string emits gravitational waves toward the directions specified by discrete angles from the rotation axis. Waveforms, polarizations, and amplitudes which depend on the direction are shown explicitly.