engleski

Probing Quantum Gravity with Cherenkov Telescopes

Cherenkov telescopes play a crucial role in testing possible consequences of Quantum Gravity (QG), such as violations or deformations of Lorentz symmetry. In both cases, the photon dispersion relation is modified, making the photon group velocity energy dependent. This tiny effect, if real, could be measured using very high energy (VHE, E > 100 GeV) gamma rays crossing cosmological distances. The so-called time of flight measurements were up to now performed on individual sources with single instruments. No deviations from the special relativistic predictions have been detected, although strong constraints have been set on modified dispersion relations. In order to increase the sensitivity of QG analyses, and to perform the most robust searches for the energy-dependent photon group velocity up to date, researchers from the three major imaging Cherenkov telescopes (IACTs) experiments (H.E.S.S., MAGIC, and VERITAS) have joined forces. It is the first attempt at merging data from different instruments for this purpose, thus creating exceptionally large statistics. Moreover, combining observations from various gamma-ray sources at different redshifts alleviates the entanglement between the effects of QG and the source intrinsic time-delays. In addition, the influence of different theoretical formalisms for distance contribution were investigated and compared for the first time. In this talk, we will describe the likelihood-based analysis method developed for this purpose, and present the results obtained from simulated data. However, this is only the first part of the anticipated work. We will introduce our plans for the continuation and future endeavours in this field, specifically, for performing our analysis on real data sets.

gamma rays: general, methods: statistical, active galactic nuclei, gamma-ray bursts, pul-sars, quantum gravity, Lorentz invariance violation

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