Massive cosmic strings in Bianchi type II

TL;DR

This paper investigates cosmological models with massive cosmic strings and Bianchi type II symmetry, analyzing their behavior under self-similarity and variable gravitational and cosmological constants, revealing specific time-dependent behaviors.

Contribution

It introduces models with variable G and Lambda in Bianchi type II cosmologies with cosmic strings, analyzing their evolution under self-similarity.

Findings

G(t) increases over time for 0<ω≤1

Lambda(t) decreases over time for 0<ω≤1

G and Lambda are constant when ω=0

Abstract

We study a massive cosmic strings with BII symmetries cosmological models in two contexts. The first of them is the standard one with a barotropic equation of state. In the second one we explore the possibility of taking into account variable \textquotedblleft constants\textquotedblright ($G$ and $\Lambda ).$Both models are studied under the self-similar hypothesis. We put special emphasis in calculating the numerical values for the equations of state. We find that for $\omega\in(0,1]$, $G$, is a growing time function while $\Lambda$, behaves as positive decreasing time function. If $\omega=0,$ both \textquotedblleft constants\textquotedblright, $G$ and $\Lambda,$ behave as true constants.