Black Hole Advective Accretion Disks with Optical Depth Transition

We consider the effects of advection and radial gradients of pressure andradial drift velocity on the structure of accretion disks around black holeswith proper description of optically thick/thin transitions. We concentratedour efforts on the models with large accretion rate. Contrary to disk modelsneglecting advection, we find that continuous solutions extending from theouter disk regions to the inner edge exist for all accretion rates we haveconsidered. We show that the sonic point moves outward with increasingaccretion rate, and that in the innermost disk region advection acts as aheating process that may even dominate over dissipative heating. Despite theimportance of advection on it's structure, the disk remains geometrically thin.Global solutions of advective accretion disks, which describe continuously thetransition between optically thick outer region and optically thin inner regionare constructed and analyzed.Comment: 13 pages, 8 figures, to be published in Proceedings of the Gamov Memorial International Conference, Odessa, Ukraine, August 8-14, 2004, Cambridge Scientific Publication