Power-law relation and basal flux. Left panel a: power-law-index b between magnetic field and the emission flux proxies for different values of the basal flux determined in bins of different sizes (for all data points with magnetic field strengths below 4 G). For larger bin-sizes the basal flux, and thus the derived power law index is constant. Right panel b: same, but for data sets where we added outliers to the data. The vertical red lines indicates the bin size we use in our study. See Appendix A.