Turbulence in simulated HII regions
  We investigate the scale dependence of fluctuations inside a realistic model
of an evolving turbulent HII region and to what extent these may be studied
observationally. We find that the multiple scales of energy injection from
champagne flows and the photoionization of clumps and filaments leads to a
flatter spectrum of fluctuations than would be expected from top-down
turbulence driven at the largest scales. The traditional structure function
approach to the observational study of velocity fluctuations is shown to be
incapable of reliably determining the velocity power spectrum of our
simulation. We find that a more promising approach is the Velocity Channel
Analysis technique of Lazarian & Pogosyan (2000), which, despite being
intrinsically limited by thermal broadening, can successfully recover the
logarithmic slope of the velocity power spectrum to a precision of +-0.1 from
high resolution optical emission line spectroscopy.
