AI 中文总结
研究z~4.5时双AGN，利用JWST/NIRSpec和ALMA观测，发现LID-1166。揭示其窄线、宽Hα发射及冷气体成分，证明确实是双AGN且在富含气体并合中。发现其吸积情况及与本地黑洞-宿主质量关系，揭示SMBH增长隐藏阶段和高红移缺失群体。
AI 中文摘要
星系并合的后期阶段，即两个超大质量黑洞（SMBHs）达到千秒差距尺度的间距时，是理解SMBH增长、星系共同演化和低频引力波前身的关键阶段。然而，尽管预测此类系统在富含并合的早期宇宙中应很常见，但已确认的近距离分离（<3 kpc）双活动星系核（AGNs）仍局限于本地宇宙。本文报告发现了LID-1166，这是一个在z~4.5时投影间距约为~1.5 kpc的双AGN，是本地宇宙之外已知的首个此类系统。空间分辨的JWST/NIRSpec积分场光谱揭示了两个在空间和运动学上不同的窄线发射成分，视线速度偏移约为~ -164 km/s。两个成分还都显示出宽Hα发射，包括与伴星源相关的紧凑离核宽Hα成分，证实了两个活跃吸积的SMBHs。独立的ALMA [CII] 158 um观测揭示了与相同核相关的相应在空间和运动学上不同的冷气体成分，表明该系统是一个富含气体的并合。在后期并合过程中经历超爱丁顿吸积时，SMBHs在不确定性范围内已符合大质量椭圆星系的本地黑洞-宿主质量关系，这表明快速、隐蔽的增长可能有助于在宇宙历史早期建立这种关系。LID-1166揭示了SMBH增长之前隐藏的阶段，并指出在高红移处存在缺失的大量被严重遮挡、并合驱动的双AGN群体。
英文摘要
The late stages of galaxy mergers - when two supermassive black holes (SMBHs) reach kiloparsec-scale separations - represent a critical phase for understanding SMBH growth, galaxy co-evolution, and the progenitors of low-frequency gravitational waves. Yet confirmed close-separation (<3 kpc) dual active galactic nuclei (AGNs) remain confined to the local Universe, despite predictions that such systems should be common in the merger-rich early Universe. Here we report the discovery of LID-1166, a dual AGN with a projected separation of ~1.5 kpc at z~4.5, representing the first such system known beyond the local Universe. Spatially resolved JWST/NIRSpec integral-field spectroscopy reveals two spatially and kinematically distinct narrow-line emission components with a line-of-sight velocity offset of ~ -164 km/s. Both components additionally exhibit broad Ha emission, including a compact off-nuclei broad Ha component associated with the companion source, confirming two actively accreting SMBHs. Independent ALMA [CII] 158 um observations reveal corresponding spatially and kinematically distinct cold gas components associated with the same nuclei, demonstrating that the system is a gas-rich merger. While undergoing super-Eddington accretion during a late-stage merger, the SMBHs already lie on the local black hole-host mass relation for massive elliptical galaxies within the uncertainties, suggesting that rapid, obscured growth may help establish this relation early in cosmic history. LID-1166 reveals a previously hidden phase of SMBH growth and points to a missing population of heavily obscured, merger-driven dual AGNs at high redshift.
CommentsNat. Astron. accepted
