Correlation plot of the posterior sample of source A (a) and B (b) marginalised over all but three parameters: the surface emission frequency, log₁₀(f_*), the surface toroidal-to-poloidal magnetic-field ratio, log₁₀(α), and the radial power-law exponent of the toroidal field, p. A Gaussian mixture model has been fitted to this marginalised distribution. On the 2D correlation plots, grey iso-contours of the model are shown together with coloured ellipses representing the one-standard-deviation area of each mode. The same colours are used on the 1D plots to represent the parts of the histogram attributed to each mode, and the line represents the model. In particular, the low mode is blue, the medium mode is orange, and the high mode is green.