Variation of the 4.5 − 5.8 keV power spectrum with the photon index Γ₁. A darker color code indicates a higher value of f  ×  PSD(f). Dashes at the bottom show the photon indices of the individual spectra. Intermediate values are interpolated with a Gaussian blur. With increasing photon index the variability components shift to higher frequencies and their intensity decreases (in this energy band L₂ completely fades out toward Γ₁ ~ 2.6).