Bianchi VI_0&III models. Self-similar approach

Abstract

We study several cosmological models with Bianchi VI_0&III symmetries under the self-similar approach. We find new solutions for the "classical" perfect fluid model as well as for the vacuum model although they are really restrictive for the equation of state. We also study a perfect fluid model with time-varying constants, $G$ and $\Lambda.$ As in other models studied we find that the behaviour of $G$ and $\Lambda$ are related. If $G$ behaves as a growing time function then $\Lambda$ is a positive decreasing time function but if $G$ is decreasing then $\Lambda_{0}$ is negative. We end by studying a massive cosmic string model, putting special emphasis on calculating the numerical values of the equations of state. We show that there is no SS solution for a string model with time-varying constants.