Fig. 9

Tilt angle deviations of the measured principal axis from the true anisotropy direction (spectral extension direction) for Fig. 8 top and middle panels. Top panel shows the angle mismatch for different values of spectral slopes: \(\alpha = 1\) (black), \(\alpha = 2\) (gray), and \(\alpha = 3\) (light gray). Bottom panel shows the angle mismatch for different elliptic ratios \(\epsilon _{\mathrm{true}} = 0.05\) (black), \(\epsilon _{\mathrm{true}} = 0.1\) (gray), and \(\epsilon _{\mathrm{true}} = 0.5\) (light gray)