Abstract:

Ever since black holes are thought to be present in compact binaries or at galactic centres a large number of model solutions have been offered to explain various aspects of observations. These explanations were on a case by case basis, and timing properties required totally different models.  However,  improved observational techniques ensured new and refined spectral and timing data which kept theorists on edge and an attempt was made to obtain a general picture, purely on theoretical grounds, which is as close to reality as possible. We review these models and show that with the most general approach of viscous transonic flow solutions which also include radiative transfer processes, we can

not only get back all these special models and capture each of their positive features, we can explain far more. We discuss how the most general two component flow solution can explain the observations and extract mass of the black holes from spectral fits. We discuss what happens when sporadic magnetic fields are included.