Dr. Olaf Reimer (University of Innsbruck)
"Diffuse Galactic Gamma-Ray Emission before CTA "
Diffuse emission is the most prominent observational signature of the GeV gamma-ray sky, and was established before individual gamma-ray sources started to emerge. It became a prime source of knowledge about cosmic-ray particle interactions and radiation processes at very high energies. In contrast to the GeV domain, the search for diffuse emission at TeV-energies is still in its infancy, largely due to the predominant charged particle background that constitutes the principal instrumental challenge for observational techniques. Diffuse emission is expected in the TeV-domain too, on the Galactic scale primarily from the interaction of protons and nuclei with the interstellar gas, and by Inverse Compton scattering of high energy electron on the interstellar radiation field. Local emission is also predicted in the vicinity of cosmic accelerators in dense molecular clouds or locally enhanced radiation fields, the emission being indicative for particle escape from their acceleration region. A characterization of the phenomenon over the transition regime from diffuse emission dominance to gamma-ray source dominance will be made, emphasizing also consequences for observations and analysis techniques with the upcoming Cherenkov Telescope Array.