  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. Here
we 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 likelihood analysis of the pulsar events reconstructed for
energies above 400 GeV finds no significant variation of energy-dependent
arrival time, and 95% CL limits are then obtained on the effective LIV energy
scale after taking into account systematic uncertainties. Only a factor of
about two less constraining than the current world-best limit on a quadratic
LIV scenario, pulsars are now well established as a third and independent class
of astrophysical objects suitable to constrain the characteristic energy scale
of LIV.
