Same as Fig. 2 but for the lens system J0946+1006. Here, the NFW profile with concentration fixed by the concentration–mass relation is a worse fit to the data than the other models: a symptom is the best-fit position of the subhalo, which is very different and more uncertain than for the other profiles. Moreover, the enclosed mass in the bottom-right panel does not converge within a radius similar to the other two profiles, i.e. R_eq = 0.45 kpc. The best models and the full posterior distributions can be found in the appendix in Figs. A.1 and A.5.