Fig. 5: The steep decay phase and the correspondent spectral evolution for the extended sample.
From: Spectral index-flux relation for investigating the origins of steep decay in γ-ray bursts
In a we show an example of a light curve of an X-ray tail selected for our extended sample, taken from GRB 150323A. We report on the same plot the XRT (orange) and the BAT (blue) flux density at 1 and 50 keV, respectively. The peak flux \({F}_{\max }\) is estimated extrapolating the X-ray tail back to the BAT peak. The error bars represent 1σ uncertainties and they are derived from the Swift archive. In b we show the spectral evolution of our extended sample of GRBs, which present a steep decay at the beginning of the XRT light curve, preceded by the brightest BAT pulse since the trigger time. The evolution of α lies on the same region of the plane occupied by the original sample, indicated in gray. The error bars represent 1σ uncertainties, calculated via spectral fitting in XSPEC. In the legend, we report the name of each GRB.
