The dark side of the Universe

The knowledge of the Universe surrounding us, nevertheless the big steps forward of the last decade, presents a lot of obscure or not well understood parts, that are usually indicated with the adjective dark. These parts touch every component of the Universe: we have well known radiation in form of photons, and its dark counterpart in form of neutrinos, dark matter beside the ordinary (baryonic) matter and also an obscure form of energy whose nature is completely unknown. In this context the big challenge of the next generation cosmology is to determine the intrinsic properties of these exotic components by working on available observables and by determining new ways to look at our Universe. Astrophysicists and Cosmologists developed during the years different techniques to observe the sky, some of which focus on the static properties of the Universe (distances and topology, actual composition), while others point towards a description of its dynamics (evolution of the components' perturbations, expansion of the background and so on). As we will see in detail in this thesis, the general relativity that rules the Universe evolution works in such a way to link statical and dynamical behaviour. This feature gives the Cosmologists the possibility to infer dynamical properties starting from simple geometrical measurements, and this, in last analysis, leads to development of new techniques to study directly also the evolutionary part of the Cosmo. We already have some measurements of this kind, but the best is to come with recently developed experiments that started in the last couple of years or that should start soon. This kind of observations will concentrate on precise and complete dynamical data that hopefully will lead us to comprehend also the darkest part of our knowledge: the dark energy. My Ph.D. work has been principally focused on the study of the properties of the dark sector of the Universe using all probes actually available.