Iron Line Variability of Discoseismic Corrugation Modes

Using a fast semi-analytic raytracing code, we study the variability of relativistically broadened Fe–Kα lines due to discoseismic oscillations concentrated in the innermost regions of accretion discs around black holes. The corrugation mode, or c-mode, is of particular interest as its natural frequency corresponds well to the ∼0.1–15 Hz range observed for low-frequency quasi-periodic oscillations (LFQPOs) for lower spins. Comparison of the oscillation phase dependent variability and quasi-periodic oscillation-phase stacked Fe–Kα line observations will allow such discoseismic models to be confirmed or ruled out as a source of particular LFQPOs. The spectral range and frequency of the variability of the Fe–Kα line due to c-modes can also potentially be used to constrain the black hole spin if observed with sufficient temporal and spectral resolution.