SIMBAD references

A magnetic field dynamo in the inner regions of the accretion disk surrounding the supermassive black holes in AGNs may be the mechanism that generates magnetic fields in galaxies and in extragalactic space. We argue that the two coherent motions produced by (1) the Keplerian motion and (2) star-disk collisions, numerous in the inner region of AGN accretion disks, are both basic to the formation of a robust, coherent dynamo and consequently to the generation of large-scale magnetic fields. Star-disk collisions are frequent enough to account for an integrated dynamo gain, e¹⁰9 at 100 gravitational radii of a central black hole, many orders of magnitude greater than what is required to amplify any seed field, no matter how small. The existence of extragalactic, coherent, large-scale magnetic fields whose energies greatly exceed all but massive black hole energies is recognized. In Paper II we argue that in order to produce a dynamo that can access the free energy of black hole formation and produce all the magnetic flux in a coherent fashion, the existence of these two coherent motions in a conducting fluid is required. The differential winding of Keplerian motion is obvious; the counter-rotation of driven plumes in a rotating frame is less well known, but has been previously demonstrated in laboratory modeling. The disk structure depends on the model of α, the transport coefficient of angular momentum chosen, but fortunately the magnetic effect is independent of the disk model. Both motions are discussed in this paper. The description is preliminary to two theoretical derivations and one numerical simulation of the α-ω dynamo in Paper II.