Fermi Gamma-ray Space Telescope

Accounting for Secondary Gamma-Ray Emission Spatial Morphology in the Galactic Center

O. Macias
T. Lacroix, C. Gordon, P. Panci, C. Boehm, J. Silk

Abstract:

Excess GeV gamma rays from the Galactic Center have been measured with the Fermi Large Area Telescope (LAT). This excess appears to be robust with respect to changes in the diffuse galactic background modelling. The three main proposals for the excess are an unresolved population of millisecond pulsars (MSPs), an outburst of cosmic rays from the Galactic Center region, and self-annihilating dark matter. Secondary electrons and positrons would be injected into the interstellar medium by an unresolved population of MSPs or dark matter annihilations. These can lead to observable gamma-ray emission via inverse Compton or bremsstrahlung. In the present study we show the importance of accounting for the spatial morphology of the secondary emission. We show examples where assuming that the secondary emission has the same morphology as the primary emission leads to good fitting models erroneously being assigned bad fitting and vice versa.