Chemical abundances in Seyfert galaxies – X. Sulphur abundance estimates. Issue 2 (2nd March 2023)

• Record Type: Journal Article
• Authors: Dors, Oli L; Valerdi, M; Riffel, R A; Riffel, R; Cardaci, M V; Hägele, G F; Armah, Mark; Revalski, M; Flury, S R; Freitas-Lemes, P; Amôres, E B; Krabbe, A C; Binette, L; Feltre, A; Storchi-Bergmann, T
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 521:Issue 2(2023)
• Page Start: 1969
• Page End: 1987
• Publication Date: 2023-03-02
• Subjects: ISM: abundances -- galaxies: abundances -- galaxies: active -- galaxies: evolution -- galaxies: nuclei -- galaxies: Seyfert; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stad635
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: For the first time, the sulphur abundance relative to hydrogen (S/H) in the narrow-line regions of a sample of Seyfert 2 nuclei (Sy 2s) has been derived via direct estimation of the electron temperature. Narrow emission-line intensities from the Sloan Digital Sky Survey (SDSS) Data Release 17 (DR17) [in the wavelength range 3000 < λ(Å) < 9100] and from the literature for a sample of 45 nearby ( z < 0.08) Sy 2s were considered. Our direct estimates indicate that Sy 2s have similar temperatures in the gas region where most of the $\rm S\rm ^{+}$ ions are located in comparison with that of star-forming regions (SFs). However, Sy 2s present higher temperature values (${\sim} 10\, 000$ K) in the region where most of the $\rm S\rm ^{2+}$ ions are located relative to that of SFs. We derive the total sulphur abundance in the range of $6.2 \: \lesssim 12+\log (\rm S/H) \: \lesssim \: 7.5$, corresponding to 0.1–1.8 times the solar value. These sulphur abundance values are lower by ∼0.4 dex than those derived in SFs with similar metallicity, indicating a distinct chemical enrichment of the interstellar medium (ISM) for these object classes. The sulphur abundance relative to oxygen (S/O) values for our Sy 2 sample present an abrupt (∼0.5 dex) decrease with increasing oxygen abundance relative to hydrogen (O/H) for the high-metallicity regime [$\rm 12+\log (O/H) \: \gtrsim 8.7)$ ], what is not seen for the SFs. However, when our Sy 2 estimates are combined with those from a large sample of SFs, we did not find any dependence between S/O and O/H.