An analytic model for magneto-viscous accretion discs

A self-consistent model for a thin accretion disc is presented, in which a large-scale magnetic held is dynamo-generated with turbulent diffusion and magnetic buoyancy operating. Both magnetic and viscous stresses generally p lay a role in causing the outward radial advection of angular momentum that is necessary to allow the inflow of material. The dynamical model places c onstraints on the turbulent Mach number and on the strength of magnetic buo yancy. The general diffusivity case has the property that, for given turbul ent and buoyancy parameters, the vertical equilibrium and dynamo equations can be satisfied in more than one way.