Published online by Cambridge University Press: 12 April 2016
A natural site for water maser emission in AGNs is provided by dusty gas with properties characteristic of broad line region (BLR) clouds. Radiation shielding by dust in the clouds is critical for allowing molecular gas to exist ≤ 1 pc from the central engine. Thus, the innermost radius at which such masers appear should correspond to the grain sublimation radius rsub. We suggest a dynamical model in which the masing clouds are embedded within a magnetized accretion disk wind.