Chemical abundances in Seyfert galaxies : VII. Direct abundance determination of neon based on optical and infrared emission lines

• Autor(a) principal: Armah, Mark
• Data de Publicação: 2021
• Outros Autores: Dors Júnior, Oli Luiz, Aydar, Catarina, Cardaci, Mónica V., Hägelle, Guillermo Federico, Feltre, Anna, Riffel, Rogério, Riffel, Rogemar André, Krabbe, Angela Cristina
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/233044
• topic: Abundância estelar; Galáxias ativas; Evolucao galatica; Nucleo galatico; Galaxias seyfert; ISM: abundances; Galaxies : abundances; Galaxies : active; Galaxies : evolution; Galaxies : nuclei; Galaxies : Seyfert

For the first time, neon abundance has been derived in the narrow line region from a sample of Seyfert 2 nuclei. In view of this, we compiled from the literature fluxes of optical and infrared (IR) narrow emission lines for 35 Seyfert 2 nuclei in the local universe (z 0.06). The relative intensities of emission lines were used to derive the ionic and total neon and oxygen abundances through electron temperature estimations (Te-method). For the neon, abundance estimates were obtained by using both Te-method and IR-method. Based on photoionization model results, we found a lower electron temperature [te(Ne iii)] for the gas phase where the Ne2 + is located in comparison with t3 for the O2 + ion. We find that the differences (D) between Ne2 +/H+ ionic abundances calculated from IR-method and Te-method (assuming t3 in the Ne2 +/H+ derivation) are similar to the derivations in star-forming regions (SFs) and they are reduced by a mean factor of ∼3 when te(Ne iii) is considered. We propose a semi-empirical Ionization Correction Factor (ICF) for the neon, based on [Ne II]12.81μm, [Ne III]15.56μm, and oxygen ionic abundance ratios. We find that the average Ne/H abundance for the Seyfert 2s sample is nearly 2 times higher than similar estimate for SFs. Finally, for the very high metallicity regime (i.e. [12 + log(O/H) 8.80]) an increase in Ne/O with O/H is found, which likely indicates secondary stellar production for the neon.