Aspects of HOŘAVA-LIFSHITZ Cosmology

We review some general aspects of Hořava-Lifshitz cosmology. Formulating it in its basic version, we extract the cosmological equations and we use observational data in order to constrain the parameters of the theory. Through a phase-space analysis we extract the late-time stable solutions, and we show that bouncing and cyclic behavior can arise naturally. Concerning the effective dark energy sector we show that it can describe the phantom phase without the use of a phantom field. However, performing a detailed perturbation analysis, we see that Hořava-Lifshitz gravity in its basic version, suffers from instabilities. Therefore, suitable generalizations are required in order for this novel theory to be a candidate for the description of nature.