Séminaires

Constraining Lorentz invariance violations with the MAGIC Cherenkov telescopes using the Crab pulsar TeV emission

par Markus Gaug (Universitat Autònoma de Barcelona)

Europe/Paris
Description

Fast variations of gamma-ray flux from Active Galactic Nuclei and Gamma-Ray Bursts can constrain Lorentz Invariance Violation (LIV) because of the delayed (or advanced) arrival of photons with higher energies: this approach has lead to the current world-best limits on the energy scale of Quantum Gravity. I will report on constraints on LIV studying the gamma-ray emission up to TeV energies from the Galactic Crab pulsar, recently discovered by the MAGIC collaboration. A detailed likelihood analysis of the pulsar events reconstructed for energies above 400 GeV finds no significant delays, or advancements, and 95% CL limits are then obtained on the effective LIV energy scale after taking into account systematic uncertainties. The study finds unexpected behaviour of the pulse shapes in the region from 200 to 400 GeV, which need to be excluded from the likelihood leading to a limit of a factor of about two less  constraining than the current world-best limit on a quadratic LIV scenario. More data is needed to clarify the emission mechanism of the Crab pulsar at the highest energies, nevertheless pulsars can now be considered (again) established as a third and independent class of astrophysical objects suitable to constrain the characteristic energy scale of LIV.