Optical and X-ray properties. Upper two panels: versus HR (on the left) and the X-ray-to-optical flux ratio distribution as a function of HR (on the right). Different symbols mark X-ray luminosity and the filled/empty symbols represent the optical classification (BPT-AGN and BPT-SF, respectively). In both plots, the point with the error bars is a fake source to represent the error mean value of the parameters. Bottom two panels: distribution of the thickness parameter (on the left) and the X/O distribution (on the right) for the two optical subsamples.