Quasars represent our main lighthouses to explore the high z Universe and to investigate the processes of formation of galaxies and their central supermassive black holes. The discovery of a relationship between the central black hole and the properties of their host galaxies is a fundamental ingredient for a comprehensive interpretation of the structure and evolution of the galaxies. Of particular relevance is the understanding how this relationship evolves over the cosmic time and it can offer important clues for the study of the formation processes of galaxies and their central massive BHs. Another key issue is to explore the immediate environment of the galaxies that host powerful active nuclei to search for signature of interaction and/or merging that is considered a fundamental ingredient for triggering and fueling the nuclear activity (e.g. Heckman et al., 2014).
The characterization of the key parameters as the galaxy mass, size, morphology and their close environments are hindered by the limited resolution and sensitivity of the present instrumentation. The measurement of the properties of the QSO host galaxies is increasingly more challenging at high redshift. This is because the contrast between the bright central nucleus and the starlight from the host galaxy critically depends on the size and shape of the latter compared with that of the point spread function (PSF).
Cosmological transformation and k-corrections have been applied adopting concordant cosmological parameters. Simulation were provided by AETC tool.