Fermi Gamma-ray Space Telescope

Observation of the Earth Limb with the Fermi Large Area Telescope

F. Spada
W. Mitthumsiri, C. Sgro'

Abstract:

The Earth's limb is the brightest gamma-ray source seen by the Fermi Large Area Telescope, due to its proximity. It is produced by cosmic-ray interactions with the atmosphere, and the spectrum of the emission has a power-law shape that follows that of the parent particles. From a comparison of the measured spectrum to a simulation based on a detailed model, it is possible to cross-check the energy scale up to the TeV region as measured by the LAT.