PROFESSOR ANVAR SHUKUROV

We present recent extensive simulations of the multiphase interstellar medium (ISM) that include external gravity, differential rotation, injection of thermal and kinetic energy by supernova (SN) explosions, optically thin radiative cooling, photoelectric heating, magnetic fields, and various transport and dissipation processes. With a three-dimensional domain extending 1 kpc by 1¿kpc horizontally and 2¿kpc vertically (symmetric about the galactic mid-plane), the model routinely spans gas number densities 10-5–102/cm3, temperatures 10–108¿K and local velocities up to 103¿km/s (Mach number up to 25). We confirm that most of the modelled ISM complexity can be captured in terms of just three phases, separated by temperature borderlines at about 103 and 5 × 105¿K. The probability distribution of gas density within each phase is approximately lognormal. We clarify the connection between the fractional volume of a phase and its various proxies, and derive an exact relation between the fractional volume and the filling factors defined in terms of the volume and probabilistic averages. The correlation scale of the random flows is calculated from the velocity autocorrelation function; it is of the order of 100 pc and tends to grow with distance from the mid-plane. Despite the extreme, violent randomness of the gas flow driven by the SNe, the ISM amplifies both the mean and random magnetic fields via two distinct dynamo mechanisms. A seed magnetic field grows exponentially to reach a statistically steady state within 1.6 Gyr. Magnetic field growth rates differ for the mean field and the fluctuating field, with clear scale separation between the two elements, whose integral scales are about 0.7 and 0.3 kpc, respectively.