On the thermal instability in numerical models of the interstellar medium

We investigate with 3D hydrodynamical simulations the role played by thermal processes in the dynamical evolution of the interstellarmedium (ISM). A parametric approach of the coolingprocess shows that the observed mass fraction of the cold (< 300 K)and unstable gas (300K < T < 6000K) can not be produced by turbulentcompression or background heating of the medium alone. An analysis of theproperties of the clouds that are formed by the combined effect of the thermal and gravitational instability shows that the cloud’s scaling relations imprinted by the thermal instability (TI) are in good agreementwith observational values.