Dynamics of a string coupled to gravitational waves - Gravitational wave scattering by a Nambu-Goto straight string

TL;DR

This paper investigates how a self-gravitating Nambu-Goto string interacts with gravitational waves, showing that it does not emit waves on its own but can bend when waves pass through.

Contribution

It develops a gauge-invariant perturbation framework for analyzing the dynamics of a self-gravitating string in general relativity, including the thin string limit.

Findings

The string does not emit gravitational waves through free oscillation.

Gravitational waves cause the string to bend without emission.

The perturbation framework applies to finite-thickness strings.

Abstract

We study the perturbative dynamics of an infinite gravitating Nambu-Goto string within the general-relativistic perturbation framework. We develop the gauge invariant metric perturbation on a spacetime containing a self-gravitating straight string with a finite thickness and solve the linearized Einstein equation. In the thin string case, we show that the string does not emit gravitational waves by its free oscillation in the first order with respect to its oscillation amplitude, nevertheless the string actually bends when the incidental gravitational waves go through it.