Fabio Fontanot

Max Planck Institute for Astronomy

torek, 25. 3. 2008, ob 14h v F6

In recent years, a general consensus has been reached on the cosmological model describing the properties of the Universe as a whole. However, while the initial conditions are specified and the basic physical laws are known, the formation of galaxies is still an open problem, due to the high level of non-linearity of the processes involved. I will compare the predictions from the MOdel for the Rise of GAlaxies aNd Active nuclei (MORGANA, Monaco, Fontanot & Taffoni, 2007) with a number of observational evidencies, in order to shed light on the complex interplay between the relevant physical processes responsible for the formation and evolution of structures in the Universe. I will discuss the main improvements we introduce in MORGANA, with respect to alternative semi-analytical models. I will then present the main successes of the model. MORGANA is able to reproduce both the downsizing of AGNs (thanks to the treatment of the stellar kinetic feedback that arises in star-forming bulges as a consequence of the high level of turbulence); and the early assembly and late, almost-passive evolution of massive galaxies (thanks to the improved modeling of gas cooling and infall in Dark Matter Halos). Despite these successes, I will show in the last part of the talk that the ‘downsizing’ trend (i.e. the modest evolution of the most massive galaxies accompanied by a build-up of small galaxies at z < 1) is still not fully reproduce in MORGANA: the most significant discrepancy refers to the overprediction of the space density of low-mass galaxies at z<2.