Critical properties of spherically symmetric accretion in a fractal medium |
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| Authors: | Nirupam Roy Arnab K Ray |
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| Institution: | National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Post Bag 3, Ganeshkhind, Pune 411007, India;Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007, India;Compagnie Générale de Géophysique India Pvt. Ltd, 504B Delphi, Hiranandani Business Park, Powai, Mumbai 400076, India |
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| Abstract: | Spherically symmetric transonic accretion of a fractal medium has been studied in both the stationary and the dynamic regimes. The stationary transonic solution is greatly sensitive to infinitesimal deviations in the outer boundary condition, but the flow becomes transonic and stable when its evolution is followed through time. The evolution towards transonicity is more pronounced for a fractal medium than it is for a continuum, and in the former case the static sonic condition is met on relatively larger length scales. The dynamic approach also shows that there is a remarkable closeness between an equation of motion for a perturbation in the flow, and the metric of an analogue acoustic black hole. The stationary inflow solutions of a fractal medium are as much stable under the influence of linearized perturbations as they are for the fluid continuum. |
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| Keywords: | accretion accretion discs hydrodynamics ISM: structure |
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