Communicating the energy: accretion properties and feedback in AGN

This thesis focuses on investigating the role of nuclear activity in SMBH-host galaxy self-regulated growth. This work is based on an extensive collection of multi-band imaging and spectroscopic data. Indeed, it is now widely accepted that AGN activity can affect different phases of the interstellar medium making mandatory a multi-wavelength approach that combines the study of emitting/absorbing gas at increasing distance from the SMBH. I have studied the relationships between nuclear properties, AGN-driven outflows, and host galaxy properties by investigating two specific cases. The first one aims at understanding if and how the huge radiative output of a hyper-luminous QSO interacts with the circum-galactic medium (CGM) of the host galaxy. The second science case regards the formation of the so-called Brightest Cluster Galaxy (BCG). BCGs are the most massive and luminous galaxies residing at the center of the relaxed, virialized and undisturbed clusters in the local Universe.