A tale of emission and absorption: Decoding early quasar feedback with multiple outflow tracers

Outflows from active galactic nuclei are invoked as the principal feedback process regulating the co-evolution of supermassive black holes and their host galaxies. Their complex, multi-phase and multi-scale nature demands a comprehensive, multi-tracer approach to fully characterize their physical properties. In this talk, I will focus on the z=5-7 redshift range, and investigate the early feedback mechanisms shaping the (post-)Reionization Universe, where these processes are expected to be particularly intense and efficient. I will analyze state-of-the-art samples of quasar spectra from these early cosmic epochs, using observations from X-Shooter/VLT. For these objects, I will provide a complete characterization of nuclear and galaxy-scale outflows by exploiting the combined power of diverse emission and absorption diagnostics. These include narrow and broad blue-shifted UV absorption lines, the presence of blue-shifted wings in CIV emission, and velocity shifts in CIV and MgII profiles. I will explore the mutual interplay of these different tracers, along with their driving mechanisms and their impact on interstellar and circumgalactic media of the host galaxy. Special attention will be given to the connection between nuclear winds, revealed by asymmetric and blueshifted emission, and strong absorption features, either broad and narrow, that appear to be ubiquitous in high-z quasar spectra. This work offers new insights into AGN feedback and its role in shaping galaxies, from distant and remote cosmic epochs to the cosmos as we observe today.