Advective accretion flows: Ten years later

Ten years have passed since the global solutions of advective accretion dis ks around black holes and neutron stars were first discovered. Since then t hey are enjoying support from observers almost on a daily basis, more so in recent days with the launching of very high resolution satellites. This re view presents the development of the subject of advective accretion in last twenty five years leading to the global solutions and their applications. It also shows that apart from the standard Keplerian disk features in most part of the accretion flow, future models must incorporate the essential fe atures of the advective disks, such as the advection of energy and entropy by the flow, centrifugal barrier supported boundary layer of a black hole, steady and non-steady shocks, the bulk motion Comptonization of matter clos e to the black hole, outflows from the centrifugal barrier, etc. Since blac k holes are "black", methods of their identification must be indirect, and therefore, the solutions must be known very accurately. On the horizon, mat ter mores supersonically, but just before that it is subsonic due to centri fugal pressure dominated boundary layer or CENBOL where much of the infall energy is released and outflows are generated. In this review, we show that advective flow models treat accretion and winds onto black holes and neutr on stars in the same footing. Similarly treated are the steady and time-dep endent behaviour of the boundary layers of neutron stars and the black hole s! Several observational results are presented which support the prediction s of this advective accretion/outflow model. Signals from coalescing gravit ating waves are affected by the sub-Keplerian flows as well.