Sergijenko O. Dynamics of Expansion and Large-Scale Structure of the Universe in Cosmological Models with Scalar Field as Dark Energy

The thesis is devoted to the analysis of dynamics of expansion of homogeneous isotropic Universe and its large-scale structure formation in the multicomponent cosmological model with dark energy modeled by the minimally coupled scalar field with two different types of Lagrangian (classical and tachyonic ones) and generalized linear barotropic equation of state. It was shown that the past dynamics of expansion and future of the Universe - eternal accelerated expansion or turnaround and collapse - are completely defined by the current energy density of a scalar field and relation between its current and early equation of state parameters. The clustering properties of such models of dark energy and their imprints in the power spectrum of matter density perturbations depend on the same relation and, additionally, on the ''effective sound speed'' of a scalar field, defined by its Lagrangian. It was concluded that such scalar fields with different values of these parameters can be distinguishable in principle. The parameters of cosmological models with such types of dark energy have been constrained by confronting theoretical predictions with the corresponding observational data. The properties of such scalar field models of dark energy with best fitting parameters and possibility of their distinguishing by the observational data were analyzed.