A hidden population of high-redshift double quasars unveiled by astrometry
A hidden population of high-redshift double quasars unveiled by astrometry
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DOI：
10.1038/s41550-021-01323-1
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发表时间：
2021-04
期刊：
影响因子：
14.1
通讯作者：
Yue Shen;Yu-Ching Chen;H. Hwang;Xin Liu;N. Zakamska;M. Oguri;J. I. Li;J. Lazio;Peter Breiding-Peter-Bre
中科院分区：
文献类型：
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作者：
Yue Shen;Yu-Ching Chen;H. Hwang;Xin Liu;N. Zakamska;M. Oguri;J. I. Li;J. Lazio;Peter Breiding-Peter-Bre
星系合并在早期宇宙中经常发生，并将多个超大质量黑洞（SMBH）带入核中，在那里它们可能最终合并。识别合并后规模（即小于几个kpc）的双SMBH是理解其动力学演化和连续合并的关键途径。虽然偶然发现的~ kpc规模的双SMBH在z < 1是可能的，这样的系统是难以捉摸的在z> 2，但在限制SMBH合并的祖先的关键。红移2也标志着发光类星体的峰值活动时代，因此在高红移下探测这一空间区域对于理解类星体的演化具有特别重要的意义。然而，鉴于严格的分辨率要求，目前还没有确认的<10 kpc physical SMBH pair atz>2（参考文献，, -).在这里，我们报告了两个亚弧秒的双类星体atz> 2，发现了有针对性的搜索与一种新的天体测量技术，表明在这种系统的方法的高成功率（100%）。这些高红移的双重类星体可能是长期寻找的kpc尺度的双重SMBH，或者亚弧秒引力透镜类星体图像。其中一个双类星体（atz= 2.95）用光谱学进行了空间分辨，并稍微倾向于一个物理类星体对的场景，其投影距离为3.5 kpc（0.46″）。通过这种有针对性的方法发现的双类星体的后续观测将能够提供对kpc尺度的双SMBH atz> 2的观测约束。
Galaxy mergers occur frequently in the early Universe and bring multiple supermassive black holes (SMBHs) into the nucleus, where they may eventually coalesce. Identifying post-merger-scale (that is, less than around a few kpc) dual SMBHs is a critical pathway to understanding their dynamical evolution and successive mergers. Whereas serendipitous discovery of ~kpc-scale dual SMBHs atz< 1 is possible, such systems are elusive atz> 2 but critical in constraining the progenitors of SMBH mergers. The redshiftz≈ 2 also marks the epoch of peak activity of luminous quasars, and therefore the probing of this spatial regime at high redshift is of particular importance in understanding the evolution of quasars. However, given stringent resolution requirements, there is currently no confirmed <10 kpc physical SMBH pair atz> 2 (refs., , –). Here, we report two sub-arcsec double quasars atz> 2 that were discovered from a targeted search with a novel astrometric technique, demonstrating a high success rate (≳50%) in this systematic approach. These high-redshift double quasars could be the long-sought kpc-scale dual SMBHs, or sub-arcsec gravitationally lensed quasar images. One of these double quasars (atz= 2.95) was spatially resolved with optical spectroscopy, and slightly favours the scenario of a physical quasar pair with a projected separation of 3.5 kpc (0.46″). Follow-up observations of double quasars discovered by this targeted approach will be able to provide observational constraints on kpc-scale dual SMBHs atz> 2.