RADIATING BONDI AND COOLING SITE FLOWS

Steady accretion of a radiating gas onto a central mass point is described and compared to classic Bondi accretion. Radiation losses are essential for accretion flows to be observed. Unlike Bondi flows, radiating Bondi flows pass through a sonic point at a finite radius and become supersonic near the center. The morphology of all radiating flows is described by a single dimensionless parameter proportional to (M) over dot / MTs where T-s is the gas temperature at the sonic point. In radiating Bondi flows the relationship between the mass accretion rate and central mass, (M) over dot proportional to M-p with p similar to 1, differs significantly from the quadratic dependence in classical Bondi flows, (M) over dot proportional to M-2. Mass accretion rates onto galaxy or cluster-centered black holes estimated from traditional and radiating Bondi flows are significantly different. In radiating Bondi flows the gas temperature increases at large radii, as in the cores of many galaxy groups and clusters, allowing radiating Bondi flows to merge naturally with gas arriving from their cluster environments. Some radiating flows cool completely before reaching the center of the flow, and this also occurs in cooling site flows, in which there is no central gravitating mass.