Statistical Measurement of the Gamma-ray Source-count Distribution as a Function of Energy

Understand

Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision.

• We employ the 1-point probability distribution function of 6 years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy.
• To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 GeV and 171 GeV.
• It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ~50 GeV.