From left to right: β plotted against M_UV for z ~ 3.6, 4.9, and 6.0. The small black circles indicate individual LAEs. The vertical dashed line indicates the characteristic UV luminosity at z ~ 3, (Steidel et al. 1999). The red squares show biweight mean values of β at each M_UV bin. The biweight mean is a robust statistic for determining the central location of a distribution. The standard deviation of the biweight mean is determined based on bootstrap simulations at each magnitude bin. The solid red line is the best-fit linear function to the biweight mean values. The slopes are dβ/dM_UV=− 0.09 ± 0.03, − 0.10 ± 0.06, and − 0.04 ± 0.15 for z ~ 3.6, 4.9, and 6.0, respectively.