Comparison of the radio and Lyα luminosities for various samples of RGs. The black circles show HzRGs at z ∼ 2−3.5 from Roettgering et al. (1997), the red circles show high-excitation 3C RGs with z < 0.3 from Buttiglione et al. (2010), having assumed Lyα/Hα = 5, the blue diamonds mark the five RGs at z > 4 cited in the text, the green stars show eight HzRGs with MUSE observations, and the blue squares show the four HzRGs confirmed by this study. The blue line represents the locus of a constant ratio of L_Lyα and L_radio.