MAIO, UmbertoUmbertoMAIO2022-06-162022-06-1620222101-6275http://hdl.handle.net/20.500.12386/32358We present first results of the evolution of cold cosmic gas obtained through a set of state-of-the-art numerical simulations (ColdSIM). We model time-dependent atomic and molecular non-equilibrium chemistry coupled to HI and H2 self-shielding, various UV backgrounds as suggested by the recent literature, H2 dust grain catalysis, photoelectric heating, cosmic-ray heating, as well as hydrodynamics, star formation and feedback effects. By means of such non-equilibrium calculations we are finally able to reproduce the latest HI and H2 observational data. Both observed HI and H2 trends are well reproduced by our non-equilibrium H2-based star formation modelling. H2 depletion times remain below the Hubble time and comparable to the dynamical time at all epochs. These findings suggest that, besides HI, non-equilibrium H2 analyses are key probes for assessing the cold gas and the role of UV background radiation.ELETTRONICOenConference paper10.1051/epjconf/202225700029https://www.epj-conferences.org/articles/epjconf/abs/2022/01/epjconf_mmUniverse2021_00029/epjconf_mmUniverse2021_00029.htmlhttp://arxiv.org/abs/2111.01804v1FIS/05 - ASTRONOMIA E ASTROFISICA