Two exceptional flares of the active galaxy PKS 2155-304 at very high energy {γ-rays [gamma-rays] and their implications on blazar and fundamental physics [Elektronische Ressource] / put forward by Rolf Bühler

Dissertationsubmitted to theCombined Faculties for the Natural Sciences and for Mathematicsof the Ruperto-Carola University of Heidelberg, Germanyfor the degree ofDoctor of Natural SciencesPut forward byDipl.-Phys. Rolf Bu¨hlerborn in Ru¨sselsheimOral examination: 28 January 2009Two exceptional flares of the active galaxy PKS 2155-304at Very High Energy γ-rays and their implications onblazar and fundamental physicsReferees: Prof. Dr. Werner HofmannProf. Dr. Heinrich V¨olkAbstractIn this work an analysis and interpretation of the Very High Energy (VHE, photon energy> 200 GeV)γ-ray emission measured from the Active Galactic Nuclei (AGN) PKS 2155-304is presented. The observations were carried out with the H.E.S.S. telescopes between 2005and 2007. The source underwent two exceptional flares during this period, on 28 and 30July 2006. The fluxes observed during these nights are among the highest ever observed inVHE astronomy and provided a very rich dataset. During the first flare the source showed avery fast flux variability (∼ 200 s). No time delays could be observed between the emissionat different photon energy bands; this lack of dispersion is used to set limits on the energyscale of Lorentz Invariance violations. The second flare was observed simultaneously by theChandra X-ray satellite, yielding an unprecedented multi-wavelength view on this object.The most striking result of this night is a cubic decay of the γ-ray flux as a function of theX-ray flux.