Averaged polarization degree at 3.5–6 keV versus the equatorial ionization parameter, ξ₀, for two different surface ionization profiles with β = −2 (top) and β = 2 (bottom). For the cone geometry (left), we show the reflected-only polarization degree, p in %. For the torus (center) and bowl (right) geometries, we show the polarization degree difference, Δp in %, which is the polarization degree p of the reflecting cone subtracted from the polarization degree p of the reflecting torus or bowl, respectively, in identical configurations. The results are plotted for Θ = 40° (brown) and Θ = 70° (turquoise), and for two different inclinations: i = 79°, where reflected radiation is the only observable component (dashed lines), and i = 28°, where we show the reflected-only polarization (dotted lines) and the total observed polarization (solid lines). We show the case of ρ = ρ_c, B = 1, and unpolarized isotropic irradiation. For the torus, the configuration with Θ = 40° and i = 79° (brown dashed lines) is already under full eclipse, and hence it is not displayed.