Quantum-Spacetime Scenarios and Soft Spectral Lags of the Remarkable GRB130427A

Figure 5

Here shown is a study of the frequency of occurrence of spectral lags in our sample as a function of a minimum photon energy and without any prior assumption on high energy photons. The red (resp., blue) solid line describes the frequency of occurrence of a certain spectral-lag slope within the sample of GRB130427A events with energy grater than 5 GeV (resp., 15 GeV). Dotted/dashed lines represent the 10%, 1%, and 0.23% probability that the given frequency of occurrence of spectral lags is a chance occurrence. The peak of the 𝑑𝐸/𝑑𝑡 distribution is consistent with the estimate of −2.8 GeV/s obtained from the best-fit analysis described in Figure 4.