A Search for Dark Matter Lines with H.E.S.S. II

Abstract: Most of the matter in the universe, ~80% is thought to be dark matter- particles that have small or no interactions with standard model particles. Dark matter is an integral part of the current understanding of cosmology, and leaves signs in the movements of stars and galaxies, as well as the Cosmic Microwave Background. The erakly interacting massive particle (WIMP) is a well-studied dark matter model that would be expected to have a mass around the weak scale, 100 GeV. WIMPs annihilating in the galactic center could give rise to mono- energetic gamma-rays in addition to a more extended spectrum. This thesis details a search for a dark matter line in a region 1.5° west of the galactic center using the High Energy Stereoscopic System (H.E.S.S.) imaging air Cherenkov telescope. The inclusion of a fifth telescope in the array enabled the analysis to extend the HESS energy range down to 100 GeV for a spectral line search. At 130 GeV, a limit of 1.38 10^-27 cm^3/s on the velocity-weighted cross-section at 95% confidence limit could be set using15.2 hours of data. The analysis is the first paper using all five telescopes of H.E.S.S. II. The main subject of the thesis has been in optimization of this analysis as well as future H.E.S.S. pointings.