Pringle and Lynden-Bell used a Green function appr
Pringle and Lynden-Bell used a Green function approach to find solutions for the diffusion equation governing these structures, whose gravitational instabilities are the subject of the Toomre Q parameter. Balbus and Hawley postulated the MRI instability for them, and their rate of formation is given by the Bondi-Hoyle equations. One theory describing them correctly predicts the appearance and disappearance of a double-peak in the spectra of cataclysmic variables. That model uses Kramer's Opacity Law and features a viscosity proportional to the scale height and sound speed, a nine-equation system known as the Shakura-Sunyaev model. Advection dominated flow causes puffing in them below the Eddington limit, and magnetic field lines in these objects are dragged in the Blandford-Znajek mechanism. They are a hallmark of Active Galactic Nuclei and can power X-ray pulsars. Often displaying relativistic jets from their centers, for 10 points, name these circular regions of matter that surround quasars and black holes.
Pringle and Lynden-Bell used a Green function approach to find solutions for the diffusion equation governing these structures, whose gravitational instabilities are the subject of the Toomre Q parameter.
{Accretion Disk} (Accept {Protostellar disc} until AGN)