BPT diagrams for the individual spaxels within 2.5 arcsec of the nucleus (red points). We show four sets of models with ionisation parameter in the range , and with different scaling of the hard X-ray component relative to the accretion disk component (0.1 up to 0.5). Note the degeneracy of the solutions on this diagram; good fits to the nuclear line ratios on a BPT diagram can be obtained with different pairs of U and X-ray scaling factor. However, the excitation of helium breaks this degeneracy; see Fig. 10.