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Free keywords:
Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE,General Relativity and Quantum Cosmology, gr-qc
Abstract:
We present results from three-dimensional, numerical relativity simulations
of a tilted black hole-thick accretion disc system. The simulations are
analysed using tracer particles in the disc which are advected with the flow.
Such tracers, which we employ in these new simulations for the first time,
provide a powerful means to analyse in detail the complex dynamics of tilted
black hole-torus systems. We show how its use helps to gain insight in the
overall dynamics of the system, discussing the origin of the observed black
hole precession and the development of a global non-axisymmetric $m=1$ mode in
the disc. Our three-dimensional simulations show the presence of quasi-periodic
oscillations (QPOs) in the instantaneous accretion rate, with frequencies in a
range compatible with those observed in low mass X-ray binaries with either a
black hole or a neutron star component. The frequency ratio of the dominant low
frequency peak and the first overtone is $o_1/f \sim 1.9$, a frequency ratio
not attainable when modelling the QPOs as $p$-mode oscillations in axisymmetric
tori.
