Abstract
The evolution of accretion disks and the formation of jets around super‐massive black holes are studied by 3‐D magnetohydrodynamic simulations. The previous studies of astrophysical jets have been concentrated on the effects of large‐scale magnetic fields permeating accretion disks. However, the existence of such global magnetic fields is not evident in astrophysical objects, and their origin is not well understood. Instead, we concentrate on the effect of the magnetic fields amplified as a result of the magneto‐rotational instability in the differentially rotating disk. In our simulations, we found the emergence of accumulated toroidal magnetic fields from the inner region of the disk (a so‐called magnetic‐tower) and also the formation of jets accelerated by the magnetic pressure of the magnetic‐tower. The magnetic energy, ejected by the magnetic‐tower jet during a lifetime of an active galactic nuclei (AGNs), is about 10^46^ erg. Our results indicate that the magnetic‐tower jet can be one of the most powerful process for the formation and the evolution of the large‐scale structured magnetic .elds in the cluster of galaxies. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)