The structure and variability of dynamo driven accretion discs

A turbulent dynamo operating in an accretion disc around a black hole can produce fields strong enough so that the Maxwell stress due to the fluctuations dominates. In this dynamo driven limit, enormous localized fluctuations can be expected because the Kepler flow energy density is efficiently tapped. The detailed radial structure of this model is calculated, which for Cyg X-1, predicts a cool (Tmax ≾ 108 K), dense, thin (z0/r ≾ 10−2), and …