Results of the fitting procedure. Left column: (a) and (c) . Right column: (b) and (d) . In the top panels, for each combination of α, B₀, the other parameters of the model are marginalised; in the bottom panels, this includes B₀. The dotted white lines in the top panels indicate the contours for constant values of volume averaged ⟨B⟩ = 30, 60, 90 μG. The cyan dashed line indicates the combinations B₀ and α with the minimum total energy W_tot in electrons and magnetic field. The yellow solid contour marks the 95% confidence level error box for B₀, α. The grey boxes in the bottom panel indicate the 95% confidence interval for α. In the bottom right diagram, the cyan dashed line indicates the minimal total energy W_tot for a given α. For a discussion on the relevance of the co-location of the global minimum with the corresponding global minimum of W_tot, see the text.