Sommaire:

Since more than 10 years, an unexpected gamma-ray component over astrophysical backgrounds has been detected at GeV energies towards the Galactic center in the data of the Fermi-Large Area Telescope. Initially, this excess was considered to be hinting at GeV thermal relics annihilating in the Galactic dark matter halo. However, recent works have demonstrated that the excess is better explained by a population of millisecond pulsar-like sources in the Galactic bulge. While the excess photon flux is peaked at about few GeV, a significant high energy tail extending up to tens of GeV has been detected. Such high-energy photons are naturally explained by the inverse Compton emission of electrons and positrons emitted by millisecond pulsars.
I will present a novel study of the morphology and photon statistics of the Galactic center excess at energies above 10 GeV. This is based on an innovative method, which combines adaptive template fitting and pixel-count statistics in order to assess the role of sub-threshold point sources while minimizing the mis-modelling of Galactic diffuse emission backgrounds.

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