Three-dimensional global MHD simulations of magnetised accretion disks and jets

We carried out three-dimensional global MHD simulations of jet formation from an accretion disk threaded by large-scale magnetic fields. Numerical results show that bipolar jets with maximum speed v(jet) similar to v(Kepler) are created. The surface layer of the disk accretes faster than the equatorial part because magnetic braking most effectively affects that layer. Accretion proceeds along spiral channels which correspond to the surface avalanche flow appearing in previous axisymmetric simulations. Spirally shaped low beta (= P-gas/P-mag < 1) regions appear in the innermost part of accretion disks where toroidal magnetic fields become dominant.