Gamma-ray angular power spectrum for emission resulting from proton-proton interactions in galaxy clusters in the energy range 1−10 GeV. We show the result for the semi-analytical model of Sect. 4 for 20% and 40% loud clusters. We plot the EGB anisotropy measured by Fermi (Fermi LAT Collaboration 2012) for comparison, which is explained by unresolved blazars, and the upper limits obtained once the blazar component is subtracted (Cuoco et al. 2012). We plot the square root of ℓ(ℓ + 1)C_ℓ/ 2π, which implies that the shown quantity is directly proportional to an increase in intensity.