Top: angular dispersion function as a function of linear polarisation fraction for all pixels with |b| < 5° in the Auriga 6 model with dust allocation recipe recSF8000 and an observer at the low density position in the outer annulus. Pixels have been binned to visualise the pixel density, with yellow indicating more pixels on a logarithmic scale. The blue line is a linear fit to the pixel values of the form log₁₀(S/°) = αlog₁₀(p/%)+β. The black line correspond to the Planck Collaboration XIX (2015) fit, while the grey line is a fit to the Planck data from Planck Collaboration XII (2020). Bottom: fit coefficients α and β for the linear fits shown in the top panel, but now for all level 3 Auriga halos, as indicated in the legend. Discs indicate models that use dust allocation recipe recSF8000, while squares correspond to dust allocation recipe recT12. The stars correspond to the Planck data fits, with the same colours as in the top panel.