Distribution of the Faraday Rotation Measure in Agn Jets As A Clue for Deciding A Valid Theoretical Model

We note that extremely valuable observational clues to the formation mechanism of AGN jets are provided from the distribution of the Faraday Rotation Measure (FRM). The results of recent observations suggest that there is quite a systematic magnetic structure in the jet, indicating that some magnetodynamic process is essential in the jet formation.We have developed our MHD model (Uchida & Shibata 1985) for the formation of AGN jets, based on the magnetic action in the gravitational contraction forming the central gravitator with an accretion disk. The weak primordial intergalactic magnetic field is amplified in the contraction of frozen-in gas into the central object, and the braking of the disk rotation by amplified magnetic field allows further accretion of the disk. The reaction of this process produces magnetic twists which dynamically pinch the large scale field into a thin jet shape in propagating out along the large scale magnetic field. The gas is driven out in the direction of the axis as spinning jets in the propagation of the twist with large Alfven velocity.We show the model counterpart of the observed FRM distribution from our 3D MHD model seen from various directions, and such comparisons can determine which of the proposed models is correct.