Starbursting to Quenching: the Role of X-Ray Emission in Active Galactic Nuclei Feedback Processes.

One of the most debated topics of modern extragalactic astrophysics is the co-evolution between the SMBHs sitting in the nuclei of the galaxies and their hosts. According to the most popular models of AGN and galaxies co-evolution, starburst galaxies, unobscured quasars and inactive (and quenched) galaxies represent the different phases of an evolutionary sequence reproducing the most massive galaxies observed in the Universe. In this context, gas flows in the form of energetic outflows are postulated to play a pivotal role in this process, given that they regulate both accretion and ejection of material onto and from the SMBH, acting on the fuel from which new stars form and stopping the host galaxy growth. In order to validate this AGN-galaxy binding nature, we investigate the kinematic and physical properties of ionized and atomic gas components of the ISM of well selected AGN-galaxy systems, obtained from ultraviolet, optical, near-infrared spectroscopic analysis, to unveil the presence of outflows. In particular, we propose and test different selection criteria to isolate sources at z ~2 in the predicted feedback phase, starting from multiwavelength information collected in the COSMOS field. As a complementary approach, we also collect a large sample of X-ray selected AGNs at z < 0.8 from the SDSS database to unveil the incidence of outflows and prove the crucial role of X-ray observations for the investigation of the feedback phase. We combine the ionized/neutral gas kinematic and physical conditions with SMBH accretion and host galaxy properties, recovered from multiwavelength spectral energy distribution analysis and X-ray spectroscopic investigation, to infer the general conditions regulating the feedback processes. We also discuss our results in the context of the more recent observational and theoretical clues.