Polish Academy of Sciences, European Commission, ETH Zurich, Universitat de Barcelona
المصدر:
Physics Letters B, 668 (4) E-Prints Complutense: Archivo Institucional de la UCM Universidad Complutense de Madrid Physics letters : B E-Prints Complutense. Archivo Institucional de la UCM instname Dipòsit Digital de la UB Universidad de Barcelona Recercat. Dipósit de la Recerca de Catalunya Physics letters / B 668, 253-257 (2008). doi:10.1016/j.physletb.2008.08.053 Digital.CSIC. Repositorio Institucional del CSIC
We analyze the timing of photons observed by the MAGIC telescope during a flare of the active galactic nucleus Mkn 501 for a possible correlation with energy, as suggested by some models of quantum gravity (QG), which predict a vacuum refractive index ≃ 1 + (E / MQGn)n, n = 1, 2. Parametrizing the delay between γ-rays of different energies as Δ t = ± τl E or Δ t = ± τq E2, we find τl = (0.030 ± 0.012) s / GeV at the 2.5-σ level, and τq = (3.71 ± 2.57) × 10-6 s / GeV2, respectively. We use these results to establish lower limits MQG 1 > 0.21 × 1018 GeV and MQG 2 > 0.26 × 1011 GeV at the 95% C.L. Monte Carlo studies confirm the MAGIC sensitivity to propagation effects at these levels. Thermal plasma effects in the source are negligible, but we cannot exclude the importance of some other source effect. Physics Letters B, 668 (4) ISSN:0370-2693 ISSN:0031-9163 ISSN:1873-2445
