Black Hole Astrophysics.

Black holes are the simplest objects in nature. All the matter enter into it with the speed of light at the horizon and thus the inner boundary condition is fixed, independent of whether we study stellar mass black holes (nano-quasars) or the massive (miliquasars) and super-massive black holes (Quasars). All types of flows are thus transonic. We compare the nature of the hydrodynamic solutions of the transonic flows and show that other solutions are special cases of this solution. Similarly, we describe the radiative properties of the accretion flows and compare the radiations emitted from other solutions. [ABSTRACT FROM AUTHOR]