| Description: | In star forming disk galaxies, matter circulation between stars and the interstellar medium (ISM), in particular the energy input by random and clustered supernova (SN) explosions, determines the dynamical and chemical evolution of the ISM, and hence of the galaxy as a whole. Present day models of the ISM assume that ionization by electrons collisions is balanced by recombinations. Such collisional ionization equilibrium (CIE) implies that the cooling time is longer than the recombination times. A condition that is verified for temperatures > 10e6 K. For lower temperatures the cooling times are comparable or shorter than the recombination time scale of the ion and therefore, departures from equilibrium are expected. We have carried out new adaptive mesh refinement simulations of the turbulent magnetized ISM powered by supernovae types Ia and II (Ib+c and II) at Galactic rate in a section of the Galactic disk centred at solar circle using a resolution of 0.5 pc. The model includes background heating, heat conduction and cooling calculated on the spot and taking into account the time-dependent ionization structure of the ten most important elements in nature - H, He, C, N, O, Ne, Mg, Si, S, and Fe - and including collisional ionization by thermal electrons, autoionization, charge exchange reactions, radiative and dielectronic recombination, photoionization, comptonisation, Auger effect and ionization of H and He by photo- and Auger electrons. Cooling is essentially a time-dependent process that controls the flow dynamics, feeding back to the thermal evolution by a change in the density and internal energy distribution, which in turn modifies the thermodynamic path of non-equilibrium cooling. |
