Symbiotic starburst-black hole AGN -- I. Isothermal hydrodynamics of the mass-loaded ISM

Abstract

Compelling evidence associates the nuclei of active galaxies and massive starbursts. The symbiosis between a compact nuclear starburst stellar cluster and a massive black hole can self-consistently explain the properties of active nuclei. The young stellar cluster has a profound effect on the most important observable properties of active galaxies through its gravity, and by mass injection through stellar winds, supernovae and stellar collisions. Mass injection generates a nuclear ISM which flows under gravitational and radiative forces until it leaves the nucleus or is accreted onto the black hole or accretion disc. The radiative force exerted by the black hole--accretion disc radiation field is not spherically symmetric. This results in complex flows in which regions of inflow can coexist with high Mach number outflowing winds and hydrodynamic jets. We present two-dimensional hydrodynamic models of such nISM flows, which are highly complex and time variable. Shocked shells, jets and explosive bubbles are produced, with bipolar winds driving out from the nucleus. Our results graphically illustrate why broad emission line studies have consistently failed to identify any simple, global flow geometry. The real structure of the flows is _inevitably_ yet more complex.