Hamburg 2016 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 83: Kosmische Strahlung

T 83.1: Gruppenbericht

Mittwoch, 2. März 2016, 16:45–17:05, VMP9 SR 30

An alternative explanation for the GeV excess in the Fermi gamma ray data. — Iris Gebauer, •Wim de Boer, and Alexander Neumann — Karlsruhe Institute of Technologie, Karlsruhe, Germany

Towards the Galactic center the diffuse Fermi Gamma Ray data show a 1-3 GeV excess, which has been interpreted previously as a new source, like dark matter annihilation, contributions from millisecond pulsars or cosmic rays interacting with molecular clouds. We search for this excess in the whole Galactic Plane and find it to be perfectly correlated with the spatial distribution of the 26Al line, thought to be a tracer of SNRs. So the excess is not only found in the Galactic Center, but found everywhere, where there are molecular clouds (MCs). This excludes the dark matter annihilation interpretation. If we assume the proton spectrum in MCs to be depleted at energies below 14 GeV by a combination of trapping, solar winds and energy losses, we find a perfect description of the whole gamma ray sky. In this case the excess is not an excess, but a depletion of low energy gamma rays below a few GeV due to the depletion of the protons in MCs below 14 GeV, which happens not only in the Galactic Center, but everywhere in the Galactic Plane, where there are MCs with star formation, as proven by the identical morphology of the excess and the 1.8 MeV line of 26Al, observed by Comptel and Integral.