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Abstract

Active Galactic Nuclei (AGNs) power the most luminous sources in the Universe, and generate very energetic large-scale radio jets. These processes are important in galaxy formation models and numerical simulations, which require energy from AGNs to prevent central gas from overcooling. In this thesis we use hydrodynamical simulations to explore the impact of jets on the intra-galactic medium of individual halos, with particular focus on massive galaxies. The simulations are performed with the FLASH code, and we took advantage of the Adaptive Mesh Refinement scheme to deal with the complex, multiscale physics of AGNs on scales ranging from Megaparsec down to a few tens of parsecs. In the first part of this thesis we describe in detail the first few millions years of AGN jets, identifying precise evolutionary stages and testing our findings against theoretical models. We discuss gas circulation within the “cocoon” carved by the jet as a possible self-regulation mechanism for jet activities. In the second part, we extend the analysis to cosmologically relevant timescales, and carry on a detailed thermodynamyc analysis of the jet-gas system, including mechanical work, global energy transfer and volume fraction of the heated gas. Finally, we present a few extensions of our model such as multiple jet events, and take a few steps towards direct comparison with X-ray observations.