Contours of the constant total PD (in %) on the plane τ₀ − α_w. The red and blue lines correspond to inclinations of i = 40° and 70°, respectively. The positive PD is shown with the solid lines and the negative PD with the dotted lines. The illuminating source is taken to be (a) isotropic, (b) a blackbody unpolarized disk, (c) Comptonization in a slab, and (d) an electron-scattering dominated disk. The intrinsic PD is zero in cases (a) and (b). In case (c), the intrinsic PD is 4.24% and 8.64% for the two inclinations 40° and 70°, and in case (d), it is −0.73% and −3.46%, respectively.