Monday, July 8, 2013 - 11:00am
"The Density Variance—Mach Number Relation in Supersonic Turbulence"
Abstract. It is widely accepted that supersonic, magnetized turbulence plays a fundamental role for star formation in molecular clouds. It produces the initial dense gas seeds out of which new stars can form. However, the exact relation between gas compression, turbulent Mach number, and magnetic field strength is still poorly understood. Here, we introduce and test an analytical prediction for the relation between the density variance and the root-mean-square Mach number in supersonic, magnetized turbulent flows. We approximate the density and velocity structure of the interstellar medium as a superposition of shock waves. We obtain the density contrast considering the momentum equation for a single magnetized shock and extrapolate this result to the entire cloud. We test the analytically derived density variance—Mach number relation with numerical simulations, and find a very good agreement with simulated data with turbulent forcing parameter b=0.4, when the gas is super-Alfvénic.