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T: Teilchenphysik

T 407: Kosmische Strahlung III

T 407.2: Talk

Wednesday, March 29, 2006, 16:35–16:50, HG2-HS3

Intrinsic spectrum of 1ES1218+304 at Very High Energies — •Daniel Mazin¹, Tanja Kneiske², Thomas Bretz³, and Markus Meyer³ — ¹Max-Planck-Institut für Physik, Föhringer Ring 6, 80805 München — ²Department of Physics, University of Adelaide, 5005 Australia — ³Lehrstuhl für Astronomie, Am Hubland, D-97074 Würzburg

A distant Active Galactic Nuclei 1ES1218+304 (z=0.182) has been detected above 100 GeV with the MAGIC Telescope. Since 1ES1218+304 is very distant object, the measured differential energy spectrum at these very high energies has strong imprint of attenuation due to gamma-gamma pair production. In order to determine the intrinsic spectrum of 1ES1218+304, knowledge about the evolving Extragalactic Background Light (EBL) which is the source of the low energy photons is required. However, despite strong progress in the modelling of the EBL and in the direct measurements of it in the last years, its level remains unknown by a factor of 2 within the models and by a factor of 4 for the direct measurements. Here we discuss possible scenarios for the intrinsic spectrum of 1ES1218+304, their consistency with leptonic and hadronic models, and potential constraints on the level of the EBL.