Scatter plot of pulse width versus fluence for the full FAST sample, in which 76 “classical” bursts are marked with colored dots (upper panel). The blue solid line represents the best-fitting of . The dotted lines represent for different fixed T_B values and the green dashed line is for the critical 10³³ K. The variance of 76 bursts with respect to the fitting line versus their brightness temperatures (lower panel) and no clear dependence is found.