Publication date: May 2012
Abstract:
Near a rotating black hole, circular motion of particles, dust grains
and complex fluids have been investigated as a model for accretion of
gaseous and dusty environment in the toroidal geometry. Here we further
discuss, within the framework of general relativity, figures of
equilibrium of matter under the influence of combined gravitational and
large-scale magnetic fields, assuming that the accreted material
acquires a small (but non-vanishing) electric charge due to the
interplay of plasma processes and photoionization. We employ different
solutions for the central body (magnetized Kerr metric, or a massive
magnetic dipole) and we identify the corresponding regions of stability.
The action of gravitational and electromagnetic forces jointly determine
the regions of stable motion, in particular, whether the halo lobes
develop where particles can be captured in permanent circulation around
the central body. Therefore, our set-up is relevant in the context of
accreting compact objects where the halo motion can describe the overall
global motion through corona of an accretion disc or a geometrically
thick torus. We also investigate situations when the motion exhibits the
onset of chaos. In order to characterize the measure of chaoticness we
employ techniques of Poincare surfaces of section and Recurrence plots.
Acknowledgments: Czech-US collaboration project (ref. ME09036) and the
Czech Science Foundation program (ref. P209/10/P190) are gratefully
acknowledged for their continued support.
Authors:
Karas, Vladimir; Kovar, J.; Kopacek, O.; Kojima, Y.; Slany, P.; Stuchlik, Z.;