Top panel: F_{2−10 keV}/F_{20−100 keV} flux ratio of our sample. Lines correspond to expected values for an absorbed power-law with photon index 1.5 (dotted) and 1.9 (dashed); see text for details. The blue empty symbols indicate sources with Galactic absorption only, while red-filled ones correspond to sources with an extra intrinsic absorption. Bottom panel: X-ray column density versus the optical one computed from the E(B − V) assuming the Galactic extinction law of Cardelli et al. (1989). Triangles are Seyfert 2, squares are Seyfert 1 objects. Points marked with red arrows are upper limits.