Narrow-band imaging of 6 Seyfert-2 galaxies

For NGC5643, the diagnostic diagrams unveil a similar transition between line ratios falling in the AGN regime and those typical for HII regions as found for NGC1386, thus determining the size of the NLR. For the other four objects, all measured line ratios fall in the AGN regime. In almost all cases, both electron density and ionisation parameter decrease with radius.

Deviations from this general behaviour (such as a secondary peak) seen in both the ionisation parameter and electron density can be interpreted as signs of shocks from the interaction of a radio jet and the NLR gas. In several objects, the gaseous velocity distribution is characteristic for rotational motion in an (inclined) emission-line disk in the centre. We compare our results to those of NGC1386 and show that the latter can be considered as prototypical also for this larger sample.

We discuss our findings in detail for each object.