A Generalised Bondi Accretion Model for the Galactic Centre
  We develop an analytic, steady-state model for the gas environment in
quiescent galactic nuclei. We assume that the mass is constantly supplied by a
spherically symmetric distribution of wind emitting stars, and that gravity is
solely due to a central supermassive black hole. We show that at some finite
radius, where the Keplerian velocity is comparable to the wind velocity, the
bulk velocity vanishes. Matter generated below that radius will be accreted
onto the black hole, while matter outside it will escape the system. Under
certain conditions, the flow may become supersonic at both domains. We obtain
radial profiles of the hydrodynamic variables and verify them using a
time-dependent hydrodynamic simulation. We delineate the conditions under which
radiative cooling can be neglected, and predict the luminosity and spectrum of
the free-free X-ray emission from such a system. We discuss applications of our
solution to our own Galactic Centre and other quiescent galactic nuclei.
