Isothermal hydrodynamics of the mass - loaded ISMR

Compelling evidence associates the nuclei of active galaxies and massive star-bursts. 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 eeect on the most important observable properties of active galaxies through its gravity, and by mass injection through stellar winds, super-novae and stellar collisions. This mass-loss, injected throughout the nucleus, creates a hot nuclear interstellar medium (nISM). The cluster both acts as an optically-thin fuel reservoir and enriches the nISM with the products of nucleosynthesis. The nISM ows 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 eld is not spherically symmetric. This results in complex ows in which regions of innow can coexist with high Mach number outtowing winds and hydrodynamic jets. We present two-dimensional hydrodynamic models of such nISM ows, 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 ow geometry. The real structure of the ows is inevitably yet more complex. The structure of these nISM ows is principally determined by two dimensionless quantities. The rst is the magnitude of the stellar cluster velocity dispersion relative to the sound speed in the nISM. These speeds measure the gravitational and thermal energies in the nISM respectively, and, therefore, whether the gas is initially bound, or escapes in a thermal wind. The second parameter is the Mach number of the ill-collimated nISM ow which is driven away from the central black hole. We discuss a two-parameter classiication based on this observation which, in future papers, we will relate to empirical classiications. The interplay between the nucleus and the wider galaxy depends critically on the exchange of radiative and mechanical energy. The outbound mechanical energy transfer is governed by the nuclear stellar cluster. Active galactic nuclei will only be understood once the symbiotic relationships between the black hole, the stellar cluster, and the galaxy are considered. It is impossible to treat correctly any isolated component. Our conceptually simple and self-consistent Symbiotic Model explains the observed complexity of active galaxies without ad hoc measures.