A new tool to derive chemical abundances in Type-2 Active Galactic Nuclei

We present a new tool for the analysis of the emission lines of the gas in the Narrow Line Region (NLR) around Active Galactic Nuclei (AGN). This new tool is can be used in large samples of objects in a consistent way using different sets of optical emission-lines taking into the account possible variations from the O/H - N/O re- lation. The code compares certain observed emission-line ratios sensitive to total oxygen abundance, nitrogen-to-oxygen ratio and ionization parameter with the pre- dictions from a large grid of photoionization models calculated under the most usual conditions of the NLR. We applied our method to a sample of Seyfert 2 galaxies with optical emission-line fluxes from the literature. Our results confirm the high metallicity of the objects of the sample, with N/O values consistent with a large secondary production of N. The obtained ionization parameters for this sample are much larger than those for star-forming object at the same metallicity.