Astrophysics with the Sunyaev-Zel’dovich effect in clusters of galaxies

Clusters of galaxies are unique systems in the universe. Being the largest gravitation- ally bound and virialized structures, they are “at the crossroads of astrophysics and cosmology”. They host three main components: galaxies; hot, optically-thin plasma and non-baryonic dark matter. The Sunyaev–Zel’dovich effect, arising from the scattering of the photons of the cosmic microwave background off the free electrons in the ionized intra-cluster plasma, is one of the most valuable probes of cluster properties. Among these, cluster mass is the most important one, since it plays a central role in cluster-based cosmological studies. Direct measurements of the Sunyaev–Zel’dovich signal allow the investigation of the thermal pressure and of the projected velocity of the intra-cluster plasma along the observer’s line of sight. This Thesis is devoted to the study of these quantities, which both play a relevant role in getting accurate estimates of cluster masses. More specifically, we focussed on: (i) the development and validation of an improved imaging algorithm to produce maps of the thermal component of the Sunyaev–Zel’dovich effect; (ii) an application of the kinetic Sunyaev–Zel’dovich effect to investigate cluster rotation. To this end, we used microwave data from real cluster observations with the Planck satellite, and mock data from a set of hydrodynamical simulations of galaxy clusters. Both these studies yielded interesting results, which can shed new light on largely addressed but yet unresolved issues in modern cluster science.