Figure 6: Observational constraints on the polarisation fraction of the AME at 23 GHz for individual regions and on all sky (see Table 1). The horizontal lines correspond to different theoretical predictions in this frequency band, both for electric dipole emission (ED) and magnetic dipole emission (MD) models. The solid line shows the expected polarisation fraction for the Cold Neutral Medium (spinning dust) model proposed by [34]. The dotted and dashed lines correspond to the polarisation fraction for MD from perfectly aligned grains consisting of a single magnetic domain [37]. The polarisation fraction from randomly oriented magnetic inclusions [42] is shown by the dot-dashed and dot-dot-dashed lines.