to the X-ray Baldwin effect is given by $A=1.64\pm0.05$ and $B=-0.12\pm0.04$. [*Chandra*]{}/HEG observations are available for only 5 objects in the quasar regime, and at these luminosities we obtained $A=1.5\pm0.3$ and $B=-0.16\pm0.22$.

![image](slope_NH_qso.ps){width="9cm"}

![image](intercept_NH_qso.ps){width="9cm"}

Seyfert regime {#sec:Syregime}
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Fitting the simulated data with Eq.\[eq:fit\_XBE\] in the Seyfert regime, we found that the slope obtained becomes flatter for increasing values of the equatorial column density of the torus (Fig.\[fig:slope\_NH\], left panel). This is related to the fact that the iron K$\alpha$ $EW$ is tightly connected to both $N_{\rm\,H}^{\rm\,T}$ and $\theta_{\mathrm{OA}}$, so that $EW$ is more strongly dependent on $\theta_{\mathrm{OA}}$ (and thus on its variation) for low values of $N_{\rm\,H}^{\rm\,T}$, which results in a steeper slope. On the other hand, when $N_{\rm\,H}^{\rm\,T}$ increases the dependence on $\theta_{\mathrm{OA}}$ becomes weaker, and the slope flatter. As shown in Fig.\[fig:slope\_NH\] (left panel), while the values of $B$ obtained by the $\theta_{\mathrm{OA}}-L_{\mathrm{X}}$ relationships of @Burlon:2011cr and @Hasinger:2008ve are similar along the whole range of $N_{\rm\,H}^{\rm\,T}$ considered, flatter slopes are obtained for that of @Maiolino:2007bh. In particular for the latter relationship the correlation becomes positive for $\log N_{\rm\,H}^{\rm\,T}\gtrsim 24$.

By combining the observations of the X-ray Baldwin effect with our simulations we can extrapolate the average value 