Standing Shocks in Trans-Magnetosonic Accretion Flows onto a Black Hole
  Fast and slow magnetosonic shock formation is presented for stationary and axisymmetric magnetohydrodynamical (MHD) accretion flows onto a black hole. The shocked black hole accretion solution must pass through magnetosonic points at some locations outside and inside the shock location. We analyze critical conditions at the magnetosonic points and the shock conditions. Then, we show the restrictions on the flow parameters for strong shocks. We also show that a very hot shocked plasma is obtained for a very high-energy inflow with small number density. Such a MHD shock can appear very close to the event horizon, and can be expected as a source of high-energy emissions. Examples of shocked MHD accretion flows are presented in the Schwarzschild case. 
M. Takahashi, J. Goto, K. Fukumura, D. Rilett and S. Tsuruta