Arnab Kumar Ray

Research Summary:

The following is the summary of the research work done after having joined the HRI on 16th. February, 2004.

The inviscid and thin accretion disc is a well understood model system in accretion studies. Modelling such a disc like a dynamical system in a mathematical parameter space, gives a clear idea of the nature of the critical points of the stationary solutions of the flow. The outer critical point is saddle type while the inner critical point is centre type. This fact, coupled with the outer boundary condition of the flow, allows for a complete understanding of all the important qualitative features of the flow solutions, which conventionally would only be achieved by numerical integration. Furthermore, this analysis also gives a tighter upper bound on the admissible range of values for the angular momentum of the sub-Keplerian flow through the saddle point. To address the adverse implications regarding the physical realizability of a solution passing through the saddle point, it has then been demonstrated by use of a mathematical model, that a temporal evolution of the flow is a very likely non-perturbative mechanism for the selection of an inflow solution that passes through the saddle type critical point.

Preprints:

• A dynamical systems approach to an inviscid and thin accretion disc, Arnab K. Ray and J. K. Bhattacharjee, 2004 (submitted).

Other Activities:

• Presented a seminar on the topic of An Accretion Disc as a Dynamical System at the HRI on 17th. March, 2004.