Quasi-periodic oscillations in the X-ray light curves from relativistic tori

We use a relativistic ray-tracing code coupled to a relativistic hydrodynamics code to analyze the X-ray emission from a pressure-supported oscillating torus around a black hole. Solving the relativistic radiative transfer equation along each photon path, we calculate the X-ray light curves, power spectra, and broadened emission lines, as seen by a distant observer from various inclinations. We show that a strong correlation exists between the intrinsic frequencies of the torus normal modes and the extrinsic frequencies seen in the observed light-curve power spectrum. This correlation demonstrates the feasibility of the oscillating-torus model to explain the multiple peaks seen in black hole high-frequency quasi-periodic oscillations. Observations of these features can provide important information about the torus as well as the black hole.