The Bicoherence as a Diagnostic for Models of High Frequency QPOs

We discuss the use of the bicoherence - a measure of the phase coupling of oscillations at different frequencies - as a diagnostic between different models for high frequency quasi-periodic oscillations from Galactic black hole candidates. We show that this statistic is capable of finding qualitative distinctions between different hot spot models which produce nearly identical Fourier power density spectra. Finally, we show that proposed new timing missions should detect enough counts to make real use of this statistic.