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arXiv 1104.5325astro-ph.CO
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HBLR和非HBLR Seyfert 2半导体的电离机制

Ionization Mechanisms of HBLR and Non-HBLR Seyfert 2 Galaxies

Po-Chieh Yu, Chorng-Yuan Hwang

摘要:

通过比较一些光发射线比,研究了隐宽线区(HBLR)和非HBLR Seyfert 2星系的电离机制。我们注意到非HBLR Seyfert 2星系的[N II]6583/H_α比值明显高于HBLR Seyfert 2星系,而其他谱线比值,如[O III]/H_β和[O I]/H_β则与之相似。为了探讨这种差异的根源,我们探讨了不同的电离模型,如光电离,星爆,和冲击模型的理论结果。我们发现,这些模型都不能解释具有太阳丰度的非HBLR Seyfert 2星系的高[N II]6583/H_α比值,高[N II]6583/H_α必须由增强的氮丰度来再现。由于氮的过剩可以从后主序星阶段的红超巨星中获得,我们认为观测到的非HBLR Seyfert 2的氮过剩可能是由恒星演化引起的,HBLR和非HBLR Seyfert 2星系之间可能存在演化联系。

英文摘要:

We investigate the ionization mechanisms for hidden broad-line region (HBLR) and non-HBLR Seyfert 2 galaxies by comparing some optical emission line ratios. We note that the [N II]6583/H_alpha ratio of the non-HBLR Seyfert 2 galaxies is significantly higher than that of the HBLR Seyfert 2 galaxies while other line ratios, such as [O III]/H_beta and [O I]/H_beta are similar. To probe the origin of this difference, we explore theoretical results of different ionization models, such as photoionization, starburst, and shock models. We find that none of these models can explain the high [N II]6583/H_alpha ratio of the non-HBLR Seyfert 2 galaxies with solar abundance; the high [N II]6583/H_alpha must be reproduced from enhanced nitrogen abundance. Since nitrogen overabundance can be achieved from the dredge-up of red supergiants in the post-main-sequence stage, we suggest that the observed nitrogen overabundance of the non-HBLR Seyfert 2 might be caused by stellar evolution, and there could be an evolutionary connection between the HBLR and non-HBLR Seyfert 2 galaxies.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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