Articulo
On the central abundances of Active Galactic Nuclei and Star-forming Galaxies
Autor
Dors Jr., O. L.
Cardaci, Mónica Viviana
Hägele, Guillermo Federico
Rodrigues, I.
Grebel, E. K.
Pilyugin, L. S.
Freitas Lemes, P.
Krabbe, A. C.
Institución
Resumen
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 (the theoretical calibration of Storchi-Bergmann et al. 1998), via the direct Te-method, and the central intersect abundances in the host galaxies determined from the radial abundance gradients. We found that the T<sub>e</sub>-method underestimates the oxygen abundances by up to ∼2 dex (with average value of ~0.8 dex) compared to the abundances derived through the strong-line method. This con- firms 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 abun- dances 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 at- tainable abundance in galaxies (~2 times the solar value). This suggests that there is no extraordinary chemical enrichment of the NLRs of AGNs. Facultad de Ciencias Astronómicas y Geofísicas Instituto de Astrofísica de La Plata