Perfect fluid scalar-tensor cosmologies

A method is investigated which enables exact solutions to be found for k=0 Friedmann cosmological models with a perfect fluid satisfying the equation of states p= (-1), where is constant and 02, in scalar-tensor gravity theories with an arbitrary form for the gravitational coupling function (), which defines the theory. A number of explicit solutions are investigated for p=0 universes and inflationary universes, including those for theories in which () has a power-law dependence on the scalar field. When p=- new varieties of inflation arise in which a (t) t^nexp (H₀t^m).