Asymmetry a_asym of the Lyman α line (see Sect. 5.2) as a function of the axis ratio of the UV continuum counterpart, similar to Figs. 16 and 17. The black dots show the median values in bins, indicated by the widths of their error bars in x-direction with the first and last quartiles of the values in each bin indicated by the y-axis error bar. The top left cross shows the median errors in both directions, the grey dashed line indicates a symmetric line. Only objects with UV continuum counterparts are shown.