ON THE ORIGIN OF OBSCURING TORI IN THE GALACTIC NUCLEUS AND ACTIVE GALACTIC NUCLEI

Differences between Seyfert 1 and Seyfert 2 galaxies can be explained by the existence of obscuring tori at distances a few parsecs from cen tral black holes. In the Galaxy there exists a similar thick disk stru cture, the circumnuclear disk, at a distance approximately 1.7 pc from the Galactic center. We examine the possibility that both structures are the result of turbulence-supported viscous evolution and accumulat ion of accreted material in soft gravitational potentials of galactic nuclei. The accumulation occurs in a region where the gravitational po tential provides reduced differential rotation compared with different ial rotation in the neighboring regions. The existence of these struct ures requires that the ratio of the smooth background mass within appr oximately a few parsecs to the central black hole mass be of order 1. We also discuss how strong magnetic fields prevent such tori formation and suggest evolutionary possibilities consistent with our results.