Chemical abundances in Seyfert galaxies : X. sulphur abundance estimates

• Autor(a) principal: Dors Júnior, Oli Luiz
• Data de Publicação: 2023
• Outros Autores: Valerdi, Mabel, Riffel, Rogemar André, Riffel, Rogério, Cardaci, Mónica V., Hägelle, Guillermo Federico, Armah, Mark, Revalski, Mitchell, Flury, Sophia, Freitas-Lemes, Priscila, Amôres, Eduardo Brescansin de, Krabbe, Angela Cristina, Binette, Luc, Feltre, Anna, Storchi-Bergmann, Thaisa
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/268521
• topic: Galáxias ativas; Evolucao galatica; Formacao de galaxias; Meio interestelar; Galaxias seyfert; ISM : Abundances; Galaxies : Abundances; Galaxies : Active; Galaxies : Evolution; Galaxies : Nuclei; Galaxies : ISM; Galaxies : Seyfert

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 S+ ions are located in comparison with that of star-forming regions (SFs). However, Sy 2s present higher temperature values (⁠∼10000 K) in the region where most of the S²⁺ ions are located relative to that of SFs. We derive the total sulphur abundance in the range of 6.2 ≲ 12+log(S/H) ≲ 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 [12 + log(O/H) ≳ 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.