NEUTRINOS AND THE LARGE SCALE STRUCTURE OF THE UNIVERSE

Present-day cosmology is experiencing a rather exciting season, as many observations of unprecedented quality either have recently been performed or are just about to be carried out. In this framework, long-standing unsolved questions, such as the nature and dynamics of cold dark matter and dark energy, the laws of gravity on cosmological scales, and the detailed physics of gravitational collapse and galaxy formation, might finally be assessed and hopefully find some answers. However, to maximally extract information from such copious and precise data, theoretical modeling must join the effort and push predictions to higher levels of accuracy. In the present thesis, I investigate a number of aspects regarding the role of massive neutrinos in cosmology, considering in particular their effects on the Large Scale Structure of the universe. The presence of massive neutrinos leaves its trace on many cosmological observables, requiring us to carefully account for their effects in order not to introduce systematic errors in our theories, but also allowing us to set constraints on quantities such as the number of neutrino species, their total mass and mass hierarchy. For this reason, the study of cosmological neutrinos is not only encompassed within the boundaries of cosmology, but reaches out to fundamental physics. In the first part of my work, I present a new method to set the initial conditions for cosmological simulations that include massive neutrinos. I then move to the study of the clustering ratio (a cosmological probe that quantifies the clustering properties of the galaxy distribution) in the presence of neutrinos, assessing its constraining power using both current data (from SDSS) and a forecast of a Euclid-like survey. Finally I study the possible degeneracies between neutrino effects and the parameters introduced to account for the galaxy-matter bias in some state-of-the art models.