Density distributions of outflow-driven turbulence

Abstract

Protostellar jets and outflows are signatures of star formation and promising mechanisms for driving supersonic turbulence in molecular clouds. We quantify outflow-driven turbulence through three-dimensional numerical simulations using an isothermal version of the robust total variation diminishing code. We drive turbulence in real space using a simplified spherical outflow model, analyse the data through density probability distribution functions (PDFs), and investigate the core formation rate per free-fall time (CFRff). The real-space turbulencedriving method produces a negatively skewed density PDF possessing an enhanced tail on the low-density side. It deviates from the log-normal distributions typically obtained from Fourier-space turbulence driving at low densities, but can provide a good fit at high densities, particularly in terms of mass-weighted rather than volume-weighted density PDF. Due to this fact, we suggest that the CFRff determined from a Fourier-driven turbulence model could be comparable to that of our particular real-space-driving model, which has a ratio of solenoidal to compressional components from the resulting turbulence velocity fields of ~0.6. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.