Lyα FWHM as a function of quasar luminosities. In both panels each star represents a system with nebula detected and colors correspond to the percentage of the quasar Lyα luminosity (integrated within the ±FWHM of the nebula) with respect to the bolometric luminosity. Top: Lyα FWHM at the center of the nebula, computed from the first point in the velocity dispersion radial profiles (Figure 11) as a function of bolometric luminosity of the quasar. The median values of bins A2 and A3 are indicated with blue squares and error-bars indicating the range of L_bol within each bin. The dashed gray line represents a power law fit to the data points. Bottom: Distance from the data points to the power law fit shown in the top panel.