Intrinsic 2 − 10 keV luminosity (top panel) and Δ(α_OX) (bottom panel) as a function of CIV velocity v_CIV. WISSH non-BAL objects are shown as purple dots. The dispersion around the best fits (solid red lines) is given by plotting ≈200 realisations considering the values of slope and intercept within 1σ of the sampled marginalised posterior distribution (see Figures D.1b and D.1c, and Table D.1 for further details).