Viscosity-driven Winds from Magnetized Accretion Disks

We present an analytic model in which an inefficiently radiating accretion disk drives an upward wind from its surfaces. The accretion process is controlled simultaneously by a global magnetic field penetrating the disk and by the viscosity of the accreting plasma. It is shown that energy is transported radially outward within the accreting flow, associated with the viscous angular momentum transport in the same direction, and that this addition of energy from the inner region to the disk enables the latter to drive an upward wind. The parameter that specifies the strength of the wind is determined uniquely in terms of a naturally introduced viscosity parameter.