Global monopole in scalar tensor theory

TL;DR

This paper extends the global monopole solution to scalar-tensor theories, specifically Brans-Dicke gravity, analyzing its properties and effects on test particles, with both numerical and exact solutions presented.

Contribution

It provides new solutions for global monopoles in Brans-Dicke theory and explores their gravitational effects, expanding understanding beyond general relativity.

Findings

Monopole solutions depend on arbitrary parameters, reducing to known cases.

In Brans-Dicke theory, monopoles exert gravitational pull, unlike in general relativity.

Numerical analysis of spacetime variables in Brans-Dicke theory.

Abstract

The well known monopole solution of Barriola and Vilenkin (BV) resulting from the breaking of a global SO(3) symmetry is extended in general relativity along with a zero mass scalar field and also in Brans-Dicke(BD) theory of gravity.In the case of BD theory, the behaviour of spacetime and other variables such as BD scalar field and the monopole energy density have been studied numerically.For monopole along with a zero mass scalar field, exact solutions are obtained and depending upon the choice of arbitary parameters, the solutions either reduce to the BV case or to a pure scalar field solution as special cases.It is interesting to note that unlike the BV case the global monopole in the BD theory does exert gravitational pull on a test particle moving in its spacetime.