Modeling the Galactic center emission from GeV to PeV

Abstract

The H.E.S.S. collaboration recently reported a new analysis of the gamma-ray diffuse emission from a “semi-annulus” region of 1.4 × 10⁻⁴ steradiants around Sagittarius A*. The gamma-ray spectral energy distribution measured from this region suggests the presence of interacting cosmic rays at PeV energies. This analysis adds a important piece to the previous measurements obtained with Fermi-LAT, H.E.S.S. and VERITAS telescopes in this particular region of the Central Molecular Zone. Here we describe this diffuse gamma-ray emission observed around the galactic center within a comprensive model implying a cosmic-ray population with a harder spectrum in the central part of the galaxy respect to the standard scenarios. With this phenomenological model we obtain the expected diffuse gamma-ray and neutrino components for this target rich region considering the energy range from GeV to PeV. While for the gamma-ray expectations we compare the results with the data of the mentioned experiments, for the expected neutrino spectra we consider the possibility to observe the signal with Cherenkov telescopes.