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

We present a method which enables exact solutions to be found for flat homogeneous and isotropic scalar-tensor cosmologies with an arbitrary ω(Φ) function and satisfying the general perfect fluid state equation P = (γ−1)ρc2. 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 PACS number(s): 04.50.+h, 04.80.+z, 98.80.Cq, 98.80.Hw Typeset using REVTEX 1