In Unification Models, Active Galactic Nuclei (AGN) are believed to be
surrounded by an axisymmetric structure of dust and gas, which greatly
influences their observed properties according to the direction from which they
are observed. The main aim of this work is to constrain the properties of this
obscuring material using X-Ray observations. The distribution of column
densities observed by Chandra in the Chandra Deep Field South is used to
determine geometrical constraints for already proposed torus models. It is
found that the best torus model is given by a classical `donut shape' with an
exponential angular dependency of the density profile. The opening angle is
strongly constrained by the observed column densities. Other proposed torus
models are clearly rejected by the X-Ray observations.Comment: 10 pages, 4 figures, submitted to A&