Shocks in relativistic viscous accretion flows around Kerr black holes (original) (raw)
Monthly Notices of the Royal Astronomical Society
We study the relativistic viscous accretion flows around the Kerr black holes. We present the governing equations that describe the steady state flow motion in full general relativity and solve them in 1.5D to obtain the complete set of global transonic solutions in terms of the flow parameters, namely specific energy (${\cal E}$), specific angular momentum (${\cal L}$) and viscosity (α). We obtain a new type of accretion solution which was not reported earlier. Further, we show for the first time to the best of our knowledge that viscous accretion solutions may contain shock waves particularly when flow simultaneously passes through both inner critical point (rin) and outer critical point (rout) before entering into the Kerr black holes. We examine the shock properties, namely shock location (rs) and compression ratio (R, the measure of density compression across the shock front) and show that shock can form for a large region of parameter space in calL−calE{\cal L}-{\cal E}calL−calE plane. We stu...
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Study of shocks in relativistic viscous accretion flow around Kerr black hole
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We study the relativistic viscous accretion flows around the Kerr black holes. We present governing equations that describe the flow motion in full general relativity and solve them to obtain the complete set of global transonic solutions in terms of the flow parameters, namely energy ( E), angular momentum ( L) and viscosity (α). We obtain a new type of accretion solution which was not reported earlier. Further, to the best of our knowledge, we show for the first time that viscous accretion solutions may contain shock waves particularly when flow simultaneously passes through both inner critical point (r_ in) and outer critical point (r_ out) before entering to the Kerr black hole. We examine the shock properties, namely shock location (r_s) and compression ratio (R, measure of density compression across the shock front) and show that shock can form for a large region of parameter space in L- E plane. We study the effect of viscous dissipation on the shock parameter space and find ...
Solutions of Two Dimensional Viscous Accretion and Winds In Kerr Black Hole Geometry
Astrophysical Journal, 1996
We extend our previous studies of shock waves and shock-free solutions in thin accretion and winds in pseudo-Newtonian geometry to the case when the flow is ``two-dimensional'' and around a ``Kerr black hole''. We present equations for fully general relativistic viscous transonic flows and classify the parameter space according to whether or not shocks form in an inviscid flow. We discuss the behaviors of shear, angular momentum distribution, heating and cooling in viscous flows. We obtain a very significant result: we find that in weak viscosity limit the presence of the standing shock waves is more generic in the sense that flows away from the equatorial plane can produce shock waves in a wider range of parameter space. Similar conclusion also holds when the angular momentum of the black hole is increased. Generally, our conclusions regarding the shape of the shock waves are found to agree with results of the existing numerical simulations of the two dimensional accretion in Schwarzschild geometry. In a strong viscosity limit, the shocks may be located farther out or disappear completely as in the pseudo-Newtonian geometry.
Steady state shocks in accretion disks around a Kerr black hole
Monthly Notices of the Royal Astronomical Society
Results of numerical simulations of shock solutions in a geometrical thin accretion disk around a Kerr black hole (BH) are presented. Using the smoothed particle hydrodynamics (SPH) technique, the influence of the central object is included by means of an effective potential, We first present the theory of standing shock formation in accretion disks around a Kerr black hole, and show that the results of our numerical simulation agree very well with the theoretical results. We find that the shocks in an inviscid flow are very stable. We also remove the ambiguity prevalent regarding the location and stability of shocks in adiabatic flows. Finally we sketch some of the astrophysical consequences of our findings in relation to accretion disks in Active Galactic Nuclei (AGN) and Quasars.
We self-consistently study the properties of the dissipative standing shock waves in an accrertion flow around a stationary black hole. We use analytical method to achieve our goal and identify an effective area in the parameter space spanned by the specific energy and the specific an-gular momentum which allows accretion flow to pass through shock hav-ing some energy dissipation. As the dissipation is increased, the parameter space is reduced and finally disappears when the dissipation is reached its critical value. We show the variation of shock location and compression ratio as a function of the specific energy and study them in terms of energy dissipation across the shock.
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