Current-Carrying Cosmic Strings in Scalar-Tensor Gravities

TL;DR

This paper investigates how scalar-tensor gravity theories modify the spacetime metric around superconducting cosmic strings, highlighting differences from general relativity due to scalar field coupling.

Contribution

It derives a new metric for cosmic strings in scalar-tensor gravity, incorporating scalar field effects and comparing with general relativity results.

Findings

Metric depends on five parameters related to string structure and scalar field

Scalar-tensor modifications alter the gravitational field around cosmic strings

Comparison shows deviations from general relativity predictions

Abstract

We study the modifications on the metric of an isolated self-gravitating bosonic superconducting cosmic string in a scalar-tensor gravity in the weak-field approximation. These modifications are induced by an arbitrary coupling of a massless scalar field to the usual tensorial field in the gravitational Lagrangian. The metric is derived by means of a matching at the string radius with a most general static and cylindrically symmetric solution of the Einstein-Maxwell-scalar field equations. We show that this metric depends on five parameters which are related to the string's internal structure and to the solution of the scalar field. We compare our results with those obtained in the framework of General Relativity.