Amplification of magnetic fields in an accretion disk with a starburst torus

It is widely believed that a black hole is surrounded by an accretion disk. Such an accretion disk should have magnetic fields whose evolution is impo rtant to understand the disk dynamics, since the viscosity in the disk must originate from magnetic turbulence. In the case of the accretion disk of A GN (active galactic nuclei) with a circum-disk star-burst region, we point out that the so-called cr-dynamo effect via radiation drag due to an exteri or radiation field around the disk works well. This is possible since the d rag time-scale is longer than the dynamical time-scale. Importantly, we fin d that the starburst AGN satisfies this criterion. Thus, the magnetic field of the accretion disk of the starburst AGN is amplified by the dynamo effe ct owing to the radiation drag. This results in enhancing the mass-accretio n rate to the massive black-hole of AGN within the star-burst region.