Magnetically Collimated Jets with High Mass Flux

Recent numerical simulations and analytical models of magnetically collimated plasma outflows from a uniformly rotating central gravitating object and/or a Keplerian accretion disk have shown that relatively low mass and magnetic fluxes reside in the produced jet. Observations however indicate that in some cases, as in jets of YSO's, the collimated outflow carries higher fluxes than these simulations predict. A solution to this problem is proposed here by assuming that jets with high mass flux originate in a central source which produces a noncollimated outflow provided that this source is surrounded by a rapidly rotating accretion disk. The relatively faster rotating disk produces a collimated wind which then forces all the enclosed outflow from the central source to be collimated too. This conclusion is confirmed by self-consistent numerical solutions of the full set of the MHD equations.