The distribution of the Faraday depth induced by galaxies, groups and clusters on a patch of sky is investigated. For instance, we utilise a halo model approach to obtain synthetic Faraday skies. Moreover, our modelling includes cluster physical as well as cosmological aspects.
A SKA sky survey will provide a large sample of Rotation Measures of polarised sources. Hence, we examine to what extent statistics of Rotation Measures of these sources can yield information about cosmic magnetic fields and cosmology.