A population of luminous accreting black holes with hidden mergers
A population of luminous accreting black holes with hidden mergers
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DOI：
10.1038/s41586-018-0652-7
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发表时间：
2018-11
期刊：
影响因子：
64.8
通讯作者：
M. Koss;L. Blecha;P. Bernhard;C. Hung;Jessica R. Lu;B. Trakhtenbrot;E. Treister;Anna K. Weigel;L. Sartori;R. Mushotzky;K. Schawinski;C. Ricci;S. Veilleux;D. Sanders
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文献类型：
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作者：
M. Koss;L. Blecha;P. Bernhard;C. Hung;Jessica R. Lu;B. Trakhtenbrot;E. Treister;Anna K. Weigel;L. Sartori;R. Mushotzky;K. Schawinski;C. Ricci;S. Veilleux;D. Sanders
人们认为，主要星系合并在促进超大质量黑洞的生长方面发挥着重要作用。然而，对这一假设的观测支持参差不齐，一些研究表明合并星系和发光类星体之间存在相关性，而另一些研究则表明没有这种关联。最近的观测表明，即使在合并的早期阶段，当星系分离得很好时，黑洞也可能会在合并驱动的气体和尘埃后面被严重遮挡——（5至40千秒差距）。合并模拟进一步表明，当两个星系核紧密分开（小于 3 千秒差距）时，这种遮蔽和黑洞吸积在最终合并阶段达到峰值。解决这个最后阶段需要将高空间分辨率红外成像和高灵敏度硬 X 射线观测相结合，以检测高度模糊的源。然而，最近在 X 射线观测中在附近（距离低于 250 兆秒差距）发现了大量模糊的发光吸积超大质量黑洞。在这里，我们报告了硬 X 射线选择黑洞的高分辨率红外观测，并发现了模糊核合并，即超大质量黑洞合并的母体。我们发现，与具有匹配恒星质量和恒星形成率的不活跃星系样本（1.1%）相比，模糊发光黑洞（测辐射热光度高于每秒 2 × 1044ergs）显示出明显（P< 0.001）过量的后期核合并（17.6%），这与理论预测一致。通过流体动力学模拟，我们证实，在最后阶段，对于遮蔽发光黑洞的富含气体的主要合并宿主来说，过度的核合并确实是最强的。
Major galaxy mergers are thought to play an important part in fuelling the growth of supermassive black holes. However, observational support for this hypothesis is mixed, with some studies showing a correlation between merging galaxies and luminous quasars,and others showing no such association,. Recent observations have shown that a black hole is likely to become heavily obscured behind merger-driven gas and dust, even in the early stages of the merger, when the galaxies are well separated, –(5 to 40 kiloparsecs). Merger simulations further suggest that such obscuration and black-hole accretion peaks in the final merger stage, when the two galactic nuclei are closely separated (less than 3 kiloparsecs). Resolving this final stage requires a combination of high-spatial-resolution infrared imaging and high-sensitivity hard-X-ray observations to detect highly obscured sources. However, large numbers of obscured luminous accreting supermassive black holes have been recently detected nearby (distances below 250 megaparsecs) in X-ray observations. Here we report high-resolution infrared observations of hard-X-ray-selected black holes and the discovery of obscured nuclear mergers, the parent populations of supermassive-black-hole mergers. We find that obscured luminous black holes (bolometric luminosity higher than 2 × 1044ergs per second) show a significant (P< 0.001) excess of late-stage nuclear mergers (17.6 per cent) compared to a sample of inactive galaxies with matching stellar masses and star formation rates (1.1 per cent), in agreement with theoretical predictions. Using hydrodynamic simulations, we confirm that the excess of nuclear mergers is indeed strongest for gas-rich major-merger hosts of obscured luminous black holes in this final stage.