2024/05/22 by O. L. Dors, Dors, O. L., M. V. Cardaci +22 · 1 citation
Environmental Science · Physics and Astronomy · #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Nuclear Physics and Applications #Nuclear physics research studies #Radioactive contamination and transfer
paper · pdf · doi:10.48550/arxiv.2405.13906
openalex publication_date 2024/05/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We derive the nitrogen and oxygen abundances in the Narrow Line Regions (NLRs) of a sample of 38 local (z < 0.4) Seyfert~2 nuclei. For that, we consider narrow optical emission line intensities and direct estimates of the electron temperatures (T\rm e-method). We find nitrogen abundances in the range 7.6 < \rm 12+log(N/H) < 8.6 (mean value 8.06±0.22) or \rm 0.4 < (N/N\odot) < 4.7, in the metallicity regime 8.3 < \rm 12+log(O/H) < 9.0. Our results indicate that the dispersion in N/H abundance for a fixed O/H value in AGNs is in agreement with that for disc \ionHii regions with similar metallicity. We show that Seyfert~2 nuclei follow a similar (N/O)-(O/H) relation to the one followed by star-forming objects. Finally, we find that active galaxies called as 'nitrogen-loud' observed at very high redshift (z > 5) show N/O values in consonance with those derived for local NLRs. This result indicates that the main star-formation event is completed in the early evolution stages of active galaxies.