Marginalized posterior density distribution of β_ani based on the joint models using ideal kinematic data. Different colors represent posterior densities corresponding to different BH masses, while the same color indicates models with identical mass parameterization but different source grid resolutions. We observe that as M_BH increases, the inferred β_ani decreases and vice versa. The inferred β_ani distributions given different M_BH spread over the prior range [−0.3,0.3], but different M_BH yield different goodness of fit to the kinematic data (as shown in Fig. 5).