Polarization radial profiles for a) extragalactic emission; b) galactic emission; and c) the overall Lyα emission. The thin orange lines show the profile corresponding to each LOS; the solid red line is the median profile; the dispersion along different LOS is represented by the two dashed red lines (first and third quartiles). The red area shows the 3σ confidence limits inferred from our bootstrap experiment (see Appendix B). The data points are taken from H11.