Results of the tests for the existence of a Lyα halo. Top panel: histogram of the flux S/Ns between r = r_in and r_CoG measured on the optimized Lyα NBs. Blue and gray histograms indicate galaxies above and below the threshold of S/N = 3 (black dashed line), Non-LAHs and LAH candidates, respectively. RID = 23135 has a negative S/N(r_in − r_CoG) and is counted as S/N(r_in − r_CoG) = 0 in the plot. Bottom panel: probability of the null hypothesis that the SB profile at r = r_in − r_CoG matches that of the target’s continuum-component profile vs. flux S/N between r = r_in and r_CoG for the LAH candidates. A black dashed line represents the border of LAHs and Non-LAHs.