Freiburg 2008 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 76: Gammaastronomie V

T 76.4: Vortrag

Freitag, 7. März 2008, 14:45–15:00, KGII-HS 2006

A Fast TeV Gamma-Ray Flare of an Active Galactic Nucleus as a Probe for Quantum Gravity — •Robert Wagner — Max-Planck-Institut für Physik, 80805 München

The constancy of the speed of light is a very basic assuption of physics. Some models for quantum gravity, however, violate Lorentz invariance, implying an energy dependence of the speed of light. The resulting dispersion may lead to measurable signatures in very-high energy (E>100 GeV) gamma-ray signals from extragalactic gamma-ray sources. In July 2005, the MAGIC (Major Air Gamma-ray Imaging Cerenkov) Telescope observed an unprecedentedly rapid gamma-ray flare of the active galactic nucleus Markarian 501, with flare doubling and halving times below 120 seconds. We use these time-tagged photon measurements to investigate possible modifications of photon propagation. The spectral timing analysis of the Markarian 501 event is presented and estimates on the mass scales allowed for quantum-gravity-induced vacuum refraction are made.