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arXiv 2109.04596astro-ph.GA
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塞弗特星系的化学丰度-- VII。基于光学和红外发射谱线直接测定氖的丰度

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

Mark Armah, O. L. Dors, C. P. Aydar, M. V. Cardaci, G. F. Hagele, Anna Feltre, R. Riffel, R. A. Riffel, A. C. Krabbe

摘要:

首次从Seyfert~2核样品中导出了窄线区的氖丰度。有鉴于此,我们根据文献资料编制了局域宇宙中35个Seyfert 2核的光学和红外窄发射线通量($z < 0.06$)。发射谱线的相对强度用于通过电子温度估计($T_{e}$ -方法)推导离子和总氖和氧丰度。对于氖,通过使用$T_{e}$ -方法和IR-方法获得丰度估计。基于光电离模型的结果,我们发现一个较低的电子温度[ $t_{e}([Ne III])$ ]的气相中的Ne $^{2+}$位于相比,$t_{3}$的O $^{2+}$离子。我们发现,用IR方法和$T_{e}-$方法计算的Ne $^{2+}$ /H $^{+}$离子丰度之差(D)(在Ne $^{2+}$ /H $^{+}$推导中假设$t_{3}$)与恒星形成区(SF)的推导结果相似,并且当考虑$t_{e}([Ne III])$时,它们减小了$\sim3$的平均因子。我们提出了一个半经验电离校正因子(ICF)的氖,根据[Ne II]12.81 $μ$ m,[ \ion{Ne}{iii} ]15.56 $μ$ m和氧离子丰度比。我们发现,平均Ne/H丰度的Seyfert 2s样品是近2倍高于类似的估计SF。最后,对于非常高的金属量制度(即[ $12+log(O/H) > 8.80$ ])的增加,在Ne/O与O/H被发现,这可能表明次级恒星生产的氖。

英文摘要:

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 ($T_{e}$-method). For the neon, abundance estimates were obtained by using both $T_{e}$-method and IR-method. Based on photoionization model results, we found a lower electron temperature [$t_{e}([Ne III])$] for the gas phase where the Ne$^{2+}$ is located in comparison with $t_{3}$ for the O$^{2+}$ ion. We find that the differences (D) between Ne$^{2+}$/H$^{+}$ ionic abundances calculated from IR-method and $T_{e}-$method (assuming $t_{3}$ in the Ne$^{2+}$/H$^{+}$ derivation) are similar to the derivations in star-forming regions (SFs) and they are reduced by a mean factor of $\sim3$ when $t_{e}([Ne III])$ is considered. We propose a semi-empirical Ionization Correction Factor (ICF) for the neon, based on [Ne II]12.81$μ$m, [\ion{Ne}{iii}]15.56$μ$m 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.

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