Can protostellar jets drive supersonic turbulence in molecular clouds?

Jets and outflows from young stellar objects have been proposed as candidates to drive supersonic turbulence in molecular clouds. Here we present the results from multidimensional jet simulations where we investigate in detail the energy and momentum deposition from jets into their surrounding environment and quantify the character of the excited turbulence with velocity probability density functions. Our study includes jet-clump interaction, transient jets, and magnetized jets. We find that collimated supersonic jets do not excite supersonic motions far from the vicinity of the jet. Supersonic fluctuations are damped quickly and do not spread into the parent cloud. Instead, subsonic, non-compressional modes occupy most of the excited volume. This is a generic feature that cannot be fully circumvented with overdense jets or magnetic fields. Nevertheless, jets are able to leave strong imprints in the cloud structure and can disrupt dense clumps. Our results question the ability of collimated jets to sustain supersonic turbulence in molecular clouds.