On the Asymptotic Behaviour of Cosmological Models in Scalar-Tensor Theories of Gravity

We study the qualitative properties of cosmological models in scalartensor theories of gravity by exploiting the formal equivalence of these theories with general relativity minimally coupled to a scalar field under a conformal transformation and field redefinition. In particular, we investigate the asymptotic behaviour of spatially homogeneous cosmological models in a class of scalar-tensor theories which are conformally equivalent to general relativistic Bianchi cosmologies with a scalar field and an exponential potential whose qualitative features have been studied previously. Particular attention is focussed on those scalar-tensor theory cosmological models, which are shown to be selfsimilar, that correspond to general relativistic models that play an important rôle in describing the asymptotic behaviour of more general models (e.g., those cosmological models that act as early-time and late-time attractors).