Quantum-Spacetime Scenarios and Soft Spectral Lags of the Remarkable GRB130427A
Figure 15
Here (d) shows data points with energy greater than 15 GeV, which illustrate the structure of our hard minibursts: a miniburst occurring between 230 and 260 seconds after trigger is preceded by a relatively long time interval ( seconds) of “high-energy silence,” and farther back in time one finds rather frequent detections of high-energy photons. Even for GRB130427A (observed in “high resolution”) the hard minibursts are composed of only a few photons, characterized by soft spectral lags, with in particular the highest-energy photon in the miniburst observed as the first photon in the miniburst. When we looked for supporting evidence for these features within the three brightest pre-GRB130427A Fermi-LAT long GRBs (other three panels in this figure (a), (b), and (c)) we did not find conclusive evidence of small bunches of photons governed by soft spectral lags. This also suggests that the size of the spectral lags within such hard minibursts gets bigger at higher redshift. We did find that in all three of these pre-GRB130427A Fermi-LAT long GRBs, when selecting only events above a suitably-high energy, the highest-energy photon was observed after a relatively large time interval of “high-energy silence,” as first photon of a phase of rather frequent detections of high-energy photons.
