ACCELERATED EXPANSION OF THE UNIVERSE THROUGH INTERACTIONS IN THE COSMIC SUBSTRATUM

Various homogeneous and isotropic cosmological models which describe the present stage of accelerated expansion of the Universe, like the ΛCDM model or (generalized) Chaplygin gas models, can be seen as specific realizations of a holographic dark energy cosmology if an interaction within the cosmic substratum is admitted. The corresponding interaction strength parameter determines the cosmological constant. The transition from decelerated to accelerated expansion arises as a pure interaction phenomenon. Different from the "standard" ΛCDM and Chaplygin gas models, the interaction based approach is characterized by non-adiabatic pressure perturbations.