The Dynamics of Gas around Active Galactic Nuclei

This paper examines the relationship between the accretion flows into the accretion disk around the black holes of active galactic nuclei (AGN), and the jets which they produce. A large-scale accretion flow around the nucleus is proposed as the thick dusty toroid structure of the unified model. Physically, this is similar to the Kahn ‘cocoon star’ model. High (super-Eddington) 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 properties over a wide variety of AGN classes. This revised version was published online in July 2006 with corrections to the Cover Date.