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The origin of obscuration in Active Galactic Nuclei (AGN) is still an opendebate. In particular, it is unclear what drives the relative contributions tothe line-of-sight column densities from galaxy-scale and torus-linkedobscuration. The latter source is expected to play a significant role inUnification Models, while the former is thought to be relevant in bothUnification and Evolutionary Models. In this work, we make use of a combinationof cosmological semi-analytic models and semi-empirical prescriptions for theproperties of galaxies and AGN, to study AGN obscuration. We consider adetailed object-by-object modelling of AGN evolution, including different AGNlight curves (LCs), gas density profiles, and also AGN feedback-induced gascavities. Irrespective of our assumptions on specific AGN LC or galaxy gasfractions, we find that, on the strict assumption of an exponential profile forthe gas component, galaxy-scale obscuration alone can hardly reproduce thefraction of $\log (N_{\rm H}/$cm$^{-2}) \geq 24$ sources at least at$z\lesssim3$. This requires an additional torus component with a thickness thatdecreases with luminosity to match the data. The torus should be present in allevolutionary stages of a visible AGN to be effective, although galaxy-scale gasobscuration may be sufficient to reproduce the obscured fraction with $22<\log(N_{\rm H}/$cm$^{-2})<24$ (Compton-thin, CTN) if we assume extremely compactgas disc components. The claimed drop of CTN fractions with increasingluminosity does not appear to be a consequence of AGN feedback, but rather ofgas reservoirs becoming more compact with decreasing stellar mass.

Probing the roles of orientation and multi-scale gas distributions in shaping the obscuration of Active Galactic Nuclei through cosmic time