Quantum-gravity analysis of gamma-ray bursts using wavelets

¹ Theory Division, CERN, 1211 Geneva 23, Switzerland e-mail: John.Ellis@cern.ch
² Department of Physics, Theoretical Physics, King's College London, Strand, London WC2R 2LS, UK e-mail: Nikolaos.Mavromatos@cern.ch
³ George P. and Cynthia W. Mitchell Institute of Fundamental Physics, Texas A & M University, College Station, TX 77843, USA Astroparticle Physics Group, Houston Advanced Research Center (HARC), Mitchell Campus, Woodlands, TX 77381, USA Academy of Athens, Division of Natural Sciences, 28 Panepistimiou Avenue, Athens 10679, Greece e-mail: Dimitri.Nanopoulos@cern.ch
⁴ Theory Division, CERN, 1211 Geneva 23, Switzerland Swiss Institute of Technology, ETH-Zürich, 8093 Zürich, Switzerland

Corresponding author: A. S. Sakharov, Alexandre.Sakharov@cern.ch

Received: 29 October 2002
Accepted: 14 February 2003

Abstract

In some models of quantum gravity, space-time is thought to have a foamy structure with non-trivial optical properties. We probe the possibility that photons propagating in vacuum may exhibit a non-trivial refractive index, by analyzing the times of flight of radiation from gamma-ray bursters (GRBs) with known redshifts. We use a wavelet shrinkage procedure for noise removal and a wavelet “zoom” technique to define with high accuracy the timings of sharp transitions in GRB light curves, thereby optimizing the sensitivity of experimental probes of any energy dependence of the velocity of light. We apply these wavelet techniques to 64 ms and TTE data from BATSE, and also to OSSE data. A search for time lags between sharp transients in GRB light curves in different energy bands yields the lower limit  GeV on the quantum-gravity scale in any model with a linear dependence of the velocity of light . We also present a limit on any quadratic dependence.