The evolution of active galactic nuclei. I - Models without stellar evolution

Abstract

The evolution of an isolated, spherically symmetric AGN is theoretically investigated using simulations. The models evolve through four stages characterized by the gas flow profile: (1) an early, pure accretion phase during which the central black hole grows at an Eddington-limited rate and the excess mass in the accretion flow accumulates in a central reservoir; (2) a subsequent flow characterized by a thermally stable accretion region near the black hole and a thermally unstable wind far from the black hole; (3) a flow with an inner acccretion region and an outer wind, where both are thermally stable; and (4) a pure accretion flow that commences when the mass of the black hole has become comparable to the initial core mass of the galactic nucleus. The duration of the stages depends on the photon efficiency of black hole accretion. 43 references.