Gravitational field around a time-like current-carrying screwed cosmic string in scalar-tensor theories

TL;DR

This paper derives the gravitational field of a current-carrying cosmic string in scalar-tensor theories with torsion, analyzing its effects on dark matter accretion and comparing with torsion-free models.

Contribution

It introduces a new solution for a superconducting cosmic string in scalar-tensor theories including torsion, and studies its physical implications.

Findings

Torsion effects can be described by contorsion and scalar gradient terms.

The gravitational field influences dark matter wake formation around the string.

Torsion modifies the gravitational effects compared to torsion-free scalar-tensor models.

Abstract

In this paper we obtain the space-time generated by a time-like current-carrying superconducting screwed cosmic string(TCSCS). This gravitational field is obtained in a modified scalar-tensor theory in the sense that torsion is taken into account. We show that this solution is comptible with a torsion field generated by the scalar field $\phi $. The analysis of gravitational effects of a TCSCS shows up that the torsion effects that appear in the physical frame of Jordan-Fierz can be described in a geometric form given by contorsion term plus a symmetric part which contains the scalar gradient. As an important application of this solution, we consider the linear perturbation method developed by Zel'dovich, investigate the accretion of cold dark matter due to the formation of wakes when a TCSCS moves with speed $v$ and discuss the role played by torsion. Our results are compared with those obtained for cosmic strings in the framework of scalar-tensor theories without taking torsion into account.