Description
Over the summer Fermi LAT will publish a new measurement of the angular power spectrum of anisotropies in the diffuse gamma-ray emission. The new data indicate the detection of significant Poissonian angular power over the energy range between 0.5 and 500 GeV. Such an observable provides valuable insight on the nature of the Diffuse Gamma-Ray Background (DGRB), i.e. the radiation produced by gamma-ray emitters not bright enough to be resolved individually by Fermi-LAT. Normally, any measurement of the DGRB is explained by building a model of the contributing unresolved sources, e.g. parametrising their abundance, energy spectrum or redshift evolution. Instead, in this talk I will interpret the new anisotropy data in a model independent way. Without relying to any specific parametrization, I will derive the composition of the DGRB in terms of multiple classes of unresolved sources and I will determine how many classes are need to best fit the data.
