Chemical abundances of Seyfert 2 AGNs IV

The aim of this work is to investigate diagram active galactic nucleus (AGN) positions according to shock parameters, shock effects on the gas temperature and ionization structures and derive a semi-empirical abundance calibration based on emission-line ratios little sensitive to the shock presence.

The models were used to reproduce optical (3000<{lambda}({AA})<7000) emission line intensities of 244 local (z~<0.4) Seyfert 2s, whose observational data were selected from Sloan Digital Sky Survey DR7. Our models suggest that shocks in Seyfert 2 nuclei have velocities in the range of 50-300km/s and imply a narrower metallicity range (0.6~<(Z/Z_{sun}_)~<1.6) than those derived using pure photoionization models. Our results indicate that shock velocity in AGNs cannot be estimated using standard optical line ratio diagrams, based on integrated spectra.