| Abstract |
The evolution of late-type galaxies is driven by the continuous formation of stars out of interstellar matter (ISM). The ISM is a highly compressible and magnetized medium, characterized by large Reynolds numbers. Supernova (SN) explosions of massive stars appear to be the major energy source in the ISM, generating turbulence,
heating the gas and also accelerating cosmic rays. The inherent complexity and nonlinearity of the system require a careful approach, especially for advanced numerical 3D parallel computer simulations. We have built a bottom-up model of a turbulent SN driven ISM over the last years, emphasizing the necessity of critical numerical resolution appropriate for the physical processes included, and for sufficiently long evolution times for a dynamical equilibrium to be established. It is shown that both for hydro- and magnetohydrodynamical simulations, the distribution of the plasma into distinct "stable" phases does not occur in contrast to the standard 3-phase model, and that instead a considerable fraction of the gas mass resides in classically thermally unstable phases. We will show that turbulence has a significant influence on the structure and the evolution of the ISM, and compare our results to current observations. The solar system itself is embedded in a superbubble, which has been modelled for the first time in a realistic ISM background medium. Some interesting results will be discussed. Finally, it will be emphasized that our results imply a change in paradigm, i.e. from a stable 3-phase medium in pressure equilibrium to a highly turbulent ISM.
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