The dynamics of gas around active Galactic nuclei

This paper examines the relationship between the accretion flows into the a ccretion disk around the black holes of active galactic nuclei (AGN), and t he jets which they produce. A large-scale accretion flow around the nucleus is proposed as the thick dusty toroid structure of the unified model. Phys ically, this is similar to the Kahn 'cocoon star' model. High (super-Edding ton) accretion rates into the accretion disk are needed. It is assumed that all black holes produce relativistic jets. However, entrainment of thermal (wind) material into the jet determines the AGN class, radio-loud or radio quiet. The jet interacts with the ambient medium as it expands, generating a cocoon of fast radiative or partially-radiative shocks around it. Such a model can explain both the radio properties and the emission line properti es over a wide variety of AGN classes.