The Discovery of a Hidden Broad-line AGN in a Bulgeless Galaxy: Keck NIR Spectroscopic Observations of SDSS J085153.64+392611.76
The Discovery of a Hidden Broad-line AGN in a Bulgeless Galaxy: Keck NIR Spectroscopic Observations of SDSS J085153.64+392611.76
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DOI：
10.3847/1538-4357/aba52c
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发表时间：
2020-07
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影响因子：
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通讯作者：
T. Bøhn;G. Canalizo;S. Satyapal;R. Pfeifle
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文献类型：
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作者：
T. Bøhn;G. Canalizo;S. Satyapal;R. Pfeifle
本文报道了在一个无凸起的Seyfert 2（Sy 2）星系SDSS J085153.64+392611.76中发现的一个活动超大质量黑洞（SMBH）。凯克近红外观测揭示了一个隐藏的宽线区域，允许在罕见的情况下，强约束可以放置在BH质量和凸起组件。使用维里质量估计，我们得到BH质量的log（MBH/M Ω）= 6.78 ± 0.50。这是唯一的Sy 2活动星系核（AGN）托管在一个无球星系的维里BH质量估计，并可以提供重要的限制BH种子人口的形成方案。缺乏一个凸起的组成部分表明，SMBH增长平稳，可能是由独立于重大合并的长期过程。在一个可检测的隆起组件的情况下，我们发现MBH-Mstellar的关系是更可靠的MBH-Mbulge的关系。此外，我们还探测到了扩展的窄Paα辐射，这使我们能够创建一条旋转曲线，在那里我们可以看到中央千秒差距内的反向旋转气体。这种反向旋转的可能原因包括一个星系棒或最近一次伴星系的飞越对内部气体的破坏。这反过来又可能触发了在当前活动星系核阶段中央SMBH上的吸积。
We report the discovery of a buried, active supermassive black hole (SMBH) in SDSS J085153.64+392611.76, a bulgeless Seyfert 2 (Sy2) galaxy. Keck near-infrared observations reveal a hidden broad-line region, allowing for the rare case where strong constraints can be placed on both the BH mass and bulge component. Using virial mass estimators, we obtain a BH mass of log(MBH/M⊙) = 6.78 ± 0.50. This is one of the only Sy2 active galactic nuclei (AGNs) hosted in a bulgeless galaxy with a virial BH mass estimate and could provide important constraints on the formation scenarios of the BH seed population. The lack of a bulge component suggests that the SMBH has grown quiescently, likely caused by secular processes independent of major mergers. In the absence of a detectable bulge component, we find the MBH–Mstellar relation to be more reliable than the MBH–Mbulge relation. In addition, we detect extended narrow Paα emission that allows us to create a rotation curve where we see counterrotating gas within the central kiloparsec. Possible causes of this counterrotation include a galactic bar or disruption of the inner gas by a recent fly-by of a companion galaxy. This in turn could have triggered accretion onto the central SMBH in the current AGN phase.