STATISTICAL PROPERTIES OF LINE CENTROID VELOCITIES AND CENTROID VELOCITY INCREMENTS IN COMPRESSIBLE TURBULENCE

We have calculated probability density functions (PDFs) of centroid ve locities and centroid velocity increments of line profiles computed fr om the output of a 512(3) simulation of compressible turbulence. The P DFs of centroid velocities calculated over the whole data cube are rou ghly Gaussian. On a smaller scale, non-Gaussian PDFs are observed in s ome cases. However, this is far from being the rule, and most of the d istributions show relatively minor deviations from a Gaussian. By cont rast, PDFs of centroid velocity increments clearly show non-Gaussian w ings that are associated with regions of increased vorticity in the fl ow and thus appear related to the phenomenon of intermittency. Investi gations of PDFs of centroid velocity increments in non-star-forming re gions thus seem a promising avenue for studying the intermittency in t he interstellar medium, as an alternative to the line-shape approach.