Kinsuk Giri, Sandip K. Chakrabarti
We study the time evolution of a rotating, axisymmetric, viscous accretion
flow around black holes using a grid based finite difference method. We use the
Shakura-Sunyaev viscosity prescription. However, we compare with the results
obtained when all the three independent components of the viscous stress are
kept. We show that the centrifugal pressure supported shocks became weaker with
the inclusion of viscosity. The shock is formed farther out when the viscosity
is increased. When the viscosity is above a critical value, the shock
disappears altogether and the flow becomes subsonic and Keplerian everywhere
except in a region close to the horizon, where it remains supersonic. We also
find that as the viscosity is increased, the amount of outflowing matter in the
wind is decreased to less than a percentage of the inflow matter. Since the
post-shock region could act as a reservoir of hot electrons or the so-called
'Compton cloud', the size of which changes with viscosity, the spectral
properties are expected to depend on viscosity strongly: the harder states are
dominated by low-angular momentum and the low viscosity flow with a significant
outflows while the softer states are dominated by the high viscosity Keplerian
flow having very little outflows.
View original:
http://arxiv.org/abs/1112.1500
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