MAGNETICALLY SUPPORTED TORI IN ACTIVE GALACTIC NUCLEI

We explore the concept that the gas tori inferred to exist around the central black holes in many active galactic nuclei (AGN) have signific ant magnetic pressure support. We derive the basic equations for magne tically supported tori with a general axisymmetric B field involving t oroidal and poloidal components. We treat strong and weak field limits assuming the aspect ratio R/a larger than unity, where R is the major radius of the torus, and a is the minor radius. For strong fields, th e major radius is influenced by the B field, whereas for weak fields o nly the minor radius is affected by the field. In the strong field lim it, stability to kink perturbations is possible only for R/a approachi ng unity, just where our theory breaks down. The weak field tori tend to be kink stable for R/a less than or similar to 13. This suggests th at magnetically supported tori in nature need to be ''fat'' in order t o be stable. This appears to be consistent with observations of tori i n AGN. We note that some fat disks around young stars and around more evolved stars represent magnetically supported tori.