A turbulent model for the interstellar medium. 1: Threshold star formation and self-gravity

Abstract

We present numerical simulations of self-gravitating turbulent compressible flows in two dimensions with model terms for local stellar heating, diffuse background heating, radiative cooling (assuming an optically thin medium), and large-scale shear. Star formation (SF) is modeled by assuming that a local heating center is turned on every time the local density exceeds a threshold value. The heating then remains on for a time typical of the lifetimes of OB stars. Supernovae, magnetic fields, and rotation effects (Coriolis and centrifugal forces) are not considered. We discuss both the structure and the evolution of the model using parameters appropiate to the interstellar medium (ISM) at the scale of 1 kpc in the plane of the Galactic disk, although many of the results should be applicable to other scales with marginally important sef-gravity. Also discussed are dynamical aspects of the turbulence in these flows.