Observations of PG 1553+113 with the MAGIC telescope [Elektronische Ressource] / Daniela Dorner

Observations of PG1553+113with the MAGIC telescopeDissertation zur Erlangung desnaturwissenschaftlichen Doktorgradesder Bayerischen Julius-Maximilians-Universit¨at Wu¨rzburgDaniela DornerausAmbergWu¨rzburg 2008AbstractAbstractBlazars are among the most luminous sources in the universe. Their extreme short-timevariability indicates emission processes powered by a supermassive black hole. With thecurrentgenerationofImagingAirCherenkov Telescopes, thesesourcesareexploredatveryhigh energies. Lowering the threshold below 100GeV and improving the sensitivity of thetelescopes, more and more blazars are discovered in this energy regime. For the MAGICtelescope, a low energy analysis has been developed allowing to reach energies of 50GeVfor the first time. The method is presented in this thesis at the example of PG1553+113measuring a spectrum between 50GeV and 900GeV.In the energy regime observed by MAGIC, strong attenuation of the gamma-rays isexpected from pair production due to interactions of gamma-rays with low-energy photonsfrom the extragalactic background light. For PG1553+113, this provides the possibilityto constrain the redshift of the source, which is still unknown.Well studied from radio to x-ray energies, PG1553+113was discovered in 2005 in the veryhigh energy regime. In total, it was observed with the MAGIC telescope for 80 hoursbetween April 2005 and April 2007.