Formation and propagation of MHD jets - relativistic jets, radiation pressure, and shock-induced rotation

We present recent results of magnetohydrodynamic (MHD) simulations of jet formation and propagation, discussing a variety of astrophysical setups. In the first approach the role of the disk magnetic flux profile and disk mass flux profile concerning the jet collimation degree is investigated. Our results suggest (and quantify) that in general magnetized outflows launched from a compact region close to the inner disk radius tend to be less collimated. The second setup considers simulation of relativistic MHD jet formation, considering jet launched from the surface of a Keplerian disks, demonstrating - for the first time - the self-collimating ability of relativistic MHD jets. We obtain Lorentz factors up to simeq 10 while acquiring a high degree of collimation of about 1 degree. We then present MHD jet formation simulations taking into account radiation pressure of a central luminous source. We investigate radiative effects on jet collimation and propagation - an environment which is interesting for outflows from massive young stars and active galactic nuclei. Finally, we present a model which explains a possible jet rotation by shock compression of an intrinsic helical magnetic field.