Large-scale properties in turbulent spherically symmetric accretion

Abstract

We study the role of turbulence in a spherically symmetric accreting system on very large spatial scales of the system. This is also a highly subsonic flow region, and here the accreting fluid is treated as nearly incompressible. It is shown here that the coupling of the mean flow and the turbulent fluctuations gives rise to a scaling relation for an effective "turbulent viscosity." This in turn leads to a dynamic scaling of sound propagation in the accretion process. As a consequence of this scaling, the sonic horizon of the transonic inflow solution is shifted inward, in comparison with the inviscid flow.