A supernova-regulated interstellar medium: Simulations of the turbulent multiphase medium

The dynamic state of the interstellar medium, heated and stirred by superno vae (SNe), is simulated using a three-dimensional, nonideal MHD model in a domain extended 0.5 x 0.5 kpc horizontally and 2 kpc vertically, with the g ravitational field symmetric about the midplane of the domain, z = 0. We in clude both Type I and Type II SNe, allowing the latter to cluster in region s with enhanced gas density. The system segregates into two main phases: a warm, denser phase and a hot, dilute gas in global pressure equilibrium; th ere is also dense, cool gas compressed into filaments, shells, and clumps b y expanding SN remnants. The filling factor of the hot phase grows with hei ght, so it dominates at \z\ greater than or similar to 0.5 kpc. The multico mponent structure persists throughout the simulation, and its statistical p arameters show little time variation. The warm gas is in hydrostatic equili brium, which is supported by thermal and turbulent pressures. The multiphas e gas is in a state of developed turbulence. The rms random velocity is dif ferent in the warm and hot phases, 10 and 40 km s(-1), respectively, at \z\ less than or similar to 1 kpc; the turbulent cell size (twice the velocity correlation scale) is about 60 pc in the warm phase.