Cosmic String in Scalar-Tensor Gravity

TL;DR

This paper investigates the gravitational effects of cosmic strings within scalar-tensor gravity, revealing an attractive force on test particles absent in General Relativity, with implications for early universe cosmology.

Contribution

It derives the metric for scalar-tensor cosmic strings in the weak-field approximation and demonstrates the existence of an attractive force on neutral test particles, contrasting with General Relativity.

Findings

The cosmic string exerts an attractive force on test particles.

The angular separation remains unchanged for scalar-tensor cosmic strings.

The force could have influenced early universe dynamics.

Abstract

The gravitational properties of a local cosmic string in the framework of scalar-tensor gravity are examined. We find the metric in the weak-field approximation and we show that, contrary to the General Relativity case, the cosmic string in scalar-tensor gravitation exerces a force on non-relativistic, neutral test particle. This force is proportional to the derivative of the conformal factor $A^{2}(\phi)$ and it is always attractive. Moreover, this force could have played an important role at the Early Universe, although nowadays it can be neglegible. It is also shown that the angular separation $\delta\varphi$ remains unaltered for scalar-tensor cosmic strings.