Clustering of Clusters as a Cosmological Probe

Galaxy clusters play a leading role in both present and planned cosmological investigations. They represent the biggest collapsed structure of the Universe, sitting on top of the highest peaks of the dark matter density field. These objects are considered from long time as cosmological probes; the possibility to link their observed properties to the fundamental quantities of their host haloes, modelled as a function of cosmological parameters, is in fact very concrete. The advantage in using these objects for this kind of studies comes from a) the presence of multiple independent methods covering the whole spectrum to determine the total halo mass: this helps in understanding the systematics that affect different procedures and then provide a robust mass estimate; b) the less sophisticated modelling required to link the observations with cosmologically relevant quantities, as for these masses the baryon physics has only a marginal influence; the same cannot be exploited with e.g. galaxies, as the link between the total mass and observable quantities is much more influenced by baryon physics. These positive aspects apply also to the case of clustering of galaxy clusters. Moreover, clusters have a large clustering signal, due to the high bias and a very negligible contribution from non-linear redshift-space distortions caused by peculiar motions of objects in virialized haloes. All of these advantages counterbalance the larger measurement uncertainties due to the paucity of cluster sample with respect to galaxy clustering analyses. Moreover, the possibility to combine all the probes the galaxy clusters can provide gives us an unique instrument to address the fundamental puzzles in the present-day cosmology. In this Thesis we will exploit the clustering of an optically selected sample of galaxy clusters, focusing in particular on the two-point correlation function.