Galaxy mergers occur frequently in the early Universe¹ 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 mergers². Whereas serendipitous discovery of ~kpc-scale dual SMBHs at z < 1 is possible³, such systems are elusive at z > 2 but critical in constraining the progenitors of SMBH mergers. The redshift z ≈ 2 also marks the epoch of peak activity of luminous quasars⁴, 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 at z > 2 (refs. ^5,6,7,8). Here, we report two sub-arcsec double quasars at z > 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 (at z = 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 at z > 2.

银河兼并早期宇宙中频繁发生¹，并把多个超大质量黑洞（SMBHs）进入细胞核，在那里他们可能最终聚结。识别合并后规模（即，小于大约几个 kpc）的双 SMBH 是了解其动态演变和连续合并的关键途径²。虽然在z  < 1 时偶然发现 ~kpc 规模的双 SMBH是可能的³，但这种系统在z  > 2 时难以捉摸，但对于限制 SMBH 合并的前身至关重要。红移z  ≈ 2 也标志着发光类星体⁴活动峰值的时期，因此在高红移下探索这种空间状态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，目前在z  > 2 处没有确认的 <10 kpc 物理 SMBH 对（参考文献^{5、6、7、8}）。在这里，我们报告了在z > 2处的两个亚弧秒双类星体， 它们是使用一种新的天体测量技术通过有针对性的搜索发现的，证明了这种系统方法的成功率很高 ( ≳ 50%)。这些高红移双类星体可能是长期寻找的 kpc 尺度双 SMBH，或亚弧秒引力透镜类星体图像。这些双类星体之一（在z = 2.95) 用光学光谱进行空间分辨，并略微倾向于物理类星体对的情况，预计分离为 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为z  > 2 处的 kpc 尺度双 SMBH 提供观测约束。