Detection of the Vela pulsar and search for Lorentz invariance violation with the fifth H.E.S.S. telescope

The fifth telescope (CT5) of the H.E.S.S. array (High Energy Stereoscopic System) was inaugurated in 2012. H.E.S.S. is designed to scrutinize the southern γ ray sky and CT5, whose threshold is about 30 GeV, allowed the Vela pulsar detection in 24 hours observation time. Some quantum gravity (QG) scenarios predict a violation of Lorentz invariance (LIV). This could manifest by additional terms ∝ (E=E_QG)ⁿ to the photon dispersion relations, where E is the light quantum energy, E_QG the typical scale at which QG processes are expected to occur and n the order of the correction. This energy dependence could be tested by time of flight measurements between photons emitted from variable (active galactic nuclei), transient (gamma ray bursts) or periodical (pulsars) astrophysical sources. This thesis presents the analysis of the CT5 collected data from the Vela pulsar. A maximum likelihood method already successfully applied to other source species has been adapted here to the Vela pulsar. No deviation from standard photon dispersion relations is observed, therefore limits have been placed on E_QG. The most restrictive result has been obtained for a superluminal linear correction to the dispersion relations E_QG>7.0 x 10¹⁵ GeV. (author)