Search for Millisecond Flares in INTEGRAL and RHESSI GRBs — towards probing Quantum Gravity with GRBs

Since the discovery of the cosmological origin of GRBs there has been growing interest in using these transient events to probe the Quantum Gravity energy scale in the range 1016–1019 GeV, up to the Planck mass scale. This energy scale can manifest itself through a modification in the electromagnetic radiation dispersion relation, specifically, an energy‐dependence of the velocity of light. To impose stringent limits on a possible modification, a flare within a GRB must be both short and significant over a wide energy band to provide a sufficient baseline for determining dt/dE, the difference in the arrival times of photons of different energies. To approach the Planck mass scale, we must measure arrival time differences on the order of 0.5 ms from soft to hard (∼10 MeV) photons within a flare for a GRB at a redshift of a few. We have searched INTEGRAL‐ and RHESSI‐observed GRBs for suitable flares, requiring a 5σ trigger on a 2 ms, 10 ms, or 100 ms time scale using only photons above 1 MeV. We present met...