CO luminosity vs. stellar mass bisector fits of AGN host galaxies (red circles) and non-active galaxies of the control sample (blue squares). The thick lines mark the bisector fits obtained by adopting a Bayesian framework (see main text). The dispersion of the fits is given by plotting 500 realizations of the bisector fits. The vertical axis on the right is derived by assuming α_CO = 3.6 M_⊙/(K km s⁻¹ pc²) and serves for illustration purposes only since we only consider L′_CO in our quantitative analysis (see Sect. 5.3).