Why do Galaxy magnetic field models fail to match radio observations?

Astronomers tested eight Galactic magnetic field models against radio polarization data from two sky surveys at 2.3 and 4.76 GHz. Models matched the *direction* of polarization reasonably well but failed to reproduce the *strength*. Local foreground features like the North Polar Spur dominate the polarized emission, suggesting current models miss crucial small-scale structures needed for accurate predictions.