Statistics Of The Galaxy Distribution PDF Download

The main objective of this thesis is to investigate the relationship between the dark and the luminous part of the Universe. Within the standard cosmological model framework, we will use galaxies as our probes to study the matter distribution in the Universe and its evolution. In order to achieve this goal, we use statistical tools to characterize the way objects are distributed in the sky. We model our measurements using a phenomenological description: the ``halo model''. However, to make robust estimations, we need to have access to a large amount of data which is made possible by the use of photometric redshift surveys. First, we look at the redshift dependence of the hierarchical amplitudes of the galaxy distribution up to order 5 using a wide photometric survey, the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS), from present day up to intermediate redshifts. We interpret these measurements in the perturbation theory framework. We found that in the weakly non-linear regime, our measurements are marginally consistent with the predictions. However, these latter slightly over-predict our measurements, which suggests the existence of higher-order bias terms. Using the halo model, we also showed that the position of the transition between the non-linear and the weakly non-linear regime is fully compatible with theoretical expectations. Then, using two-point statistics on data from the UltraVISTA-COSMOS survey, we investigate the way galaxy clustering depends on the stellar mass and the redshift beyond a redshift of one. We found that, on average, samples with higher stellar mass thresholds have higher mean clustering amplitude meaning that rarer populations are more strongly clustered. We also interpreted these measurements in the context of the halo model. Furthermore, we consider the stellar mass to halo mass ratio and follow the evolution of the peak in this quantity up to redshift z \sim ~2 trying to interpret it in terms of galaxy formation. We showed that, for the full sample, M_{h}^{peak} shifts progressively to higher halo masses at higher redshifts, an effect known as ``anti-hierarchical''. Finally, we summarize our main results and present some of our future projects.