Interaction of young stellar object jets with their accretion disk

I reexamine recent observations of velocity profiles across jets blown by young stellar objects, and argue that the observations do not support the earlier interpretation of jets rotating around their symmetry axes. Instead, I propose that interaction of the jets with a twisted-tilted (wrapped) accretion disk can form the observed asymmetry in the jets' line of sight velocity profiles. The proposed scenario is based on two plausible assumptions. (1) There is an inclination between the jet and the outer parts of the disk, such that the jet is perpendicular to the inner part of the disk; i.e., there is a twisted-tilted (wrapped) disk. (2) The disk-jet interaction slows the jet down as the jet entrains mass from the disk, with larger decelaration of jet segments closer to the tilted disk. The proposed scenario can account for the basic properties of the observed velocity profiles, while offering the advantage of not needing to refer to any magnetic jet launching model, and there is no need to invoke jet rotation with a huge amount of angular momentum.