Asymptotic and Exact Solutions of Perfect-Fluid Scalar-Tensor Cosmologies

Abstract

We present a method which enables exact solutions to be found for at homogeneous and isotropic scalar-tensor cosmologies with an arbitrary $ω(Φ)$ function and satisfying the general perfect fluid state equation $P=(γ-1)ρc^2$. This method has been used to analyze a wide range of asymptotic analytical solutions at early and late times for different epochs in the cosmic history: false vacuum inflationary models, vacuum and radiation-dominated models, and matter-dominated models. We also describe the qualitative behavior of models at intermediary times and give exact solutions at any time for some particular scalar-tensor theories.