A close quasar pair in a disk–disk galaxy merger at z = 2.17
A close quasar pair in a disk–disk galaxy merger at z = 2.17
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DOI：
10.1038/s41586-023-05766-6
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发表时间：
2022-09
期刊：
影响因子：
64.8
通讯作者：
Yu-Ching Chen;Xin Liu;A. Foord;Yue Shen;M. Oguri;Nianyi Chen;T. Di Matteo;Miguel Holgado
中科院分区：
文献类型：
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作者：
Yu-Ching Chen;Xin Liu;A. Foord;Yue Shen;M. Oguri;Nianyi Chen;T. Di Matteo;Miguel Holgado
星系合并产生一对超大质量黑洞（SMBHs），如果两个SMBHs都在快速吸积，它们可能被视为双类星体。千秒差距（kpc）尺度的分离代表了一个足够接近的物理状态，足以使合并诱导效应变得重要，但又足够宽，可以用现有的设备直接解决。虽然在低红移合并中已经观察到许多kpc尺度的双活动星系核（类星体的低光度对应物），但在宇宙正午（z≈2），即全球恒星形成和类星体活动的高峰期，还没有发现明确的双类星体。在这里，我们报告了斯隆数字巡天（SDSS） J0749 + 2255的多波长观测结果，作为一个kpc尺度的双类星体系统，由宇宙正午（z= 2.17）的星系合并所承载。我们发现了与更明亮的致密类星体核（相距0.46″或3.8 kpc）和低表面亮度潮汐特征相关的扩展宿主星系，作为星系相互作用的证据。与低红移和低亮度的星系不同，SDSS J0749 + 2255是由大质量致密盘主导的星系组成的。明显没有恒星膨胀，而且SDSS J0749 + 2255已经遵循了本地的SMBH质量-主恒星质量关系，这表明至少一些SMBH可能在其主恒星膨胀之前形成。虽然仍处于kpc尺度，主星系引力势占主导地位，但这两个SMBHs可能在0.22 Gyr左右演化成引力束缚的双星系统。
Galaxy mergers produce pairs of supermassive black holes (SMBHs), which may be witnessed as dual quasars if both SMBHs are rapidly accreting. The kiloparsec (kpc)-scale separation represents a physical regime sufficiently close for merger-induced effects to be important yet wide enough to be directly resolvable with the facilities currently available. Whereas many kpc-scale, dual active galactic nuclei—the low-luminosity counterparts of quasars—have been observed in low-redshift mergers, no unambiguous dual quasar is known at cosmic noon (z≈ 2), the peak of global star formation and quasar activity,. Here we report multiwavelength observations of Sloan Digital Sky Survey (SDSS) J0749 + 2255 as a kpc-scale, dual-quasar system hosted by a galaxy merger at cosmic noon (z= 2.17). We discover extended host galaxies associated with the much brighter compact quasar nuclei (separated by 0.46″ or 3.8 kpc) and low-surface-brightness tidal features as evidence for galactic interactions. Unlike its low-redshift and low-luminosity counterparts, SDSS J0749 + 2255 is hosted by massive compact disk-dominated galaxies. The apparent lack of stellar bulges and the fact that SDSS J0749 + 2255 already follows the local SMBH mass–host stellar mass relation, suggest that at least some SMBHs may have formed before their host stellar bulges. While still at kpc-scale separations where the host-galaxy gravitational potential dominates, the two SMBHs may evolve into a gravitationally bound binary system in around 0.22 Gyr.