Light Curves from an MHD Simulation of a Black Hole Accretion Disk

We use a relativistic ray-tracing code to calculate the light curves observed from a global general relativistic magneto-hydrodynamic simulation of an accretion flow onto a Schwarzschild black hole. We apply three basic emission models to sample different properties of the time-dependent accretion disk. With one of these models, which assumes thermal blackbody emission and free-free absorption, we can predict qualitative features of the high-frequency power spectrum from stellar-mass black holes in the “Thermal Dominant” state. The simulated power spectrum is characterized by a power law of index Γ ≈ 3 and total rms fractional variance of . 2% above 10 Hz. For each emission model, we find that the variability amplitude should increase with increasing inclination angle. On the basis of a newly-developed formalism for quantifying the significance of quasiperiodic oscillations (QPOs) in simulation data, we find that these simulations are able to identify any such features with (rms/mean) amplitudes & 1% near