On the central abundances of active galactic nuclei and star-forming galaxies
Abstract
We examine the relation between oxygen abundances in the narrow-line regions (NLRs) of active galactic nuclei (AGNs) estimated from the optical emission lines through the strong-line method, via the direct Te-method, and the central intersect abundances in the host galaxies determined from the radial abundance gradients. We found that the Te-method underestimates the oxygen abundances by up to ∼2 dex (with averaged value of ∼0.8 dex) compared to the abundances derived through the strong-line method. This confirms the existence of the so-called `temperature problem' in AGNs. We also found that the abundances in the centres of galaxies obtained from their spectra trough the strong-line method are close to or slightly lower than the central intersect abundances estimated from the radial abundance gradient both in AGNs and star-forming galaxies. The oxygen abundance of the NLR is usually lower than the maximum attainable abundance in galaxies (∼2 times the solar value). This suggests that there is no extraordinary chemical enrichment of the NLRs of AGNs.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 2015
- DOI:
- 10.1093/mnras/stv1916
- arXiv:
- arXiv:1508.07802
- Bibcode:
- 2015MNRAS.453.4102D
- Keywords:
-
- galaxies: abundances;
- galaxies: evolution;
- galaxies: formation;
- galaxies: general;
- galaxies: ISM;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted in MNRAS, 11 pages, 5 figures