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arXiv 2106.09720astro-ph.GA
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第1型活动星系核的FeII/MgII比与爱丁顿比的强相关

Strong correlation between FeII/MgII ratio and Eddington ratio of type 1 Active galactic nuclei

Jaejin Shin, Jong-Hak Woo, Tohru Nagao, Minjin Kim, Hyeonguk Bahk

摘要:

Fe Ⅱ/Mg Ⅱ线通量比已被用作活动星系核宽线区Fe/Mg丰度比的指示器。利用哈勃太空望远镜和斯隆数字巡天观测的静止坐标紫外光谱资料,我们研究了z <2时1型活动星系核的Fe Ⅱ/Mg Ⅱ比值。在AGN特性的宽动态范围内(即,黑洞质量、活动星系核光度和爱丁顿比),我们证实Fe II/Mg II比值与爱丁顿比密切相关,但与黑洞质量、活动星系核光度或红移无关。我们的研究结果表明,BLR中的金属丰度与AGN的吸积活动有物理联系,但与星系的整体性质无关(即,星系质量和光度)。关于BLR金属丰度与活动星系核吸积率的关系,我们讨论了金属冷却可能在增强气体流入宿主星系中心区,导致活动星系核高吸积率方面起着重要作用。

英文摘要:

The FeII/MgII line flux ratio has been used as an indicator of the Fe/Mg abundance ratio in the broad line region (BLR) of active galactic nuclei (AGNs). On the basis of archival rest-frame UV spectra obtained via the Hubble Space Telescope and the Sloan Digital Sky Survey, we investigate the FeII/MgII ratios of type 1 AGNs at z < 2. Over wide dynamic ranges of AGN properties (i.e., black hole mass, AGN luminosity, and Eddington ratio), we confirm that the FeII/MgII ratio strongly correlates with Eddington ratio but not with black hole mass, AGN luminosity, or redshift. Our results suggest that the metallicity in the BLR are physically related to the accretion activity of AGNs, but not to the global properties of galaxies (i.e., galaxy mass and luminosity). With regard to the relation between the BLR metallicity and the accretion rate of AGNs, we discuss that metal cooling may play an important role in enhancing the gas inflow into the central region of host galaxies, resulting in the high accretion rate of AGNs.

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