Robust limits on Lorentz violation from gamma-ray bursts

• Published in: Astroparticle physics Vol. 25; no. 6; pp. 402 - 411
• Main Authors: Ellis, John, Mavromatos, N.E., Nanopoulos, D.V., Sakharov, A.S., Sarkisyan, E.K.G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2006
• Subjects: Gamma ray burst; Lorentz invariance; Quantum gravity; Wavelet transform; Wavelet transform; 04.62.+v; 04.50.+h; Lorentz invariance; Gamma ray burst; Quantum gravity; 98.80.Cq
• ISSN: 0927-6505; 1873-2852
• DOI: 10.1016/j.astropartphys.2006.04.001

We constrain the possibility of a non-trivial refractive index in free space corresponding to an energy-dependent velocity of light: c( E) ≃ c 0(1 − E/ M), where M is a mass scale that might represent effect of quantum-gravitational space-time foam, using the arrival times of sharp features observed in the intensities of radiation with different energies from a large sample of gamma-ray bursters (GRBs) with known redshifts. We use wavelet techniques to identify genuine features, which we confirm in simulations with artificial added noise. Using the weighted averages of the time-lags calculated using correlated features in all the GRB light curves, we find a systematic tendency for more energetic photons to arrive earlier. However, there is a very strong correlation between the parameters characterizing an intrinsic time-lag at the source and a distance-dependent propagation effect. Moreover, the significance of the earlier arrival times is less evident for a subsample of more robust spectral structures. Allowing for intrinsic stochastic time-lags in these features, we establish a statistically robust lower limit: M > 0.9 × 10 16 GeV on the scale of violation of Lorentz invariance.