The isothermal shocks and their stabilities in fully relativistic accretion wedge flows onto black holes are studied. The jump condition across the shock is modified by the relativistic effects when the sound speed is comparable to the speed of light. With a new kind of instability analysis, it is found that only one of the two possible shocks is stable. The results are applied to the QPO behavior in galactic black hole candidates such as Cygnus X-1.
Yang, R., Kafatos, M. (1995) Shock Study in Fully Relativistic Isothermal Flows. II, Astronomy and Astrophysics, 295:238-244.