Statistical Properties of Line Centroid Velocities and Centroid Velocity Increments in Compressible Turbulence
Résumé
We have calculated probability density functions (PDFs) of centroid velociti and centroid velocity increments of line profiles computed from the output of a 512 simulation of compressible turbulence. The PDFs of centroid velocities calculated over the whole data cube are roughly Gaussian. On a smaller scale, non-Gaussian PDFs are observed in some cases. However, this is far from being the rule, and most of the distributions show relatively minor deviations from a Gaussian. By contrast, PDFs of centroid velocity increments clearly show non-Gaussian wings that are associated with regions of increased vorticity in the flow and thus appear related to the phenomenon of intermittency. Investigations of PDFs of centroid velocity increments in non-star4orming regions thus seem a promising avenue for studying the intermittency in the interstellar medium, as an alternative to the line-shape approach. Subject headings: hydrodynamics ISM: clouds ISM: kinematics and dynamics turbulence
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