Pre-burst events of gamma-ray bursts with light speed variation

Abstract Previous researches on high-energy photon events from gamma-ray bursts (GRBs) suggest a light speed variation v ( E ) = c ( 1 − E / E LV ) with E LV = 3.6 × 10 17  GeV , together with a pre-burst scenario that hight-energy photons come out about 10 seconds earlier than low-energy photons at the GRB source. However, in the Lorentz invariance violating scenario with an energy dependent light speed considered here, high-energy photons travel slower than low-energy photons due to the light speed variation, so that they are usually detected after low-energy photons in observed GRB data. Here we find four high-energy photon events which were observed earlier than low-energy photons from Fermi Gamma-ray Space Telescope (FGST), and analysis on these photon events supports the pre-burst scenario of high energy photons from GRBs and the energy dependence of light speed listed above.