Marginalized posterior distributions of Bianchi parameters recovered from PlanckSMICA (solid blue curves), SEVEM (dashed green curves), NILC (dot-dashed yellow curves), and Commander (dotted red curves) component-separated data for left-handed models. Planck data provide evidence in support of a Bianchi component in the phenomenological flat-decoupled-Bianchi model (panel a)) but not in the physical open-coupled-Bianchi model (panel b)). Significant differences exist between the posterior distributions shown in panel b) for each component separation method; this model is not favoured by data and parameters are in general poorly constrained.