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Abstract Kiloparsec-scale dual and offset active galactic nuclei (AGNs) are signposts of accreting supermassive black holes (SMBHs) triggered during late-stage galaxy mergers, offering crucial insights into the coevolution of SMBHs and galaxies. However, robustly confirmed systems at high redshift (e.g., z > 1) are scarce and biased toward the most luminous and unobscured systems. In this study, we systematically search for kiloparsec-scale (projected separation ∼ 22 . 9 − 17.7 + 27.5 % at z ∼ 4.5) and a higher occurrence rate of dual over offset AGNs. There is no pileup of dual/offset AGNs below ∼2kpc separations. These results generally align with predictions from the ASTRID and Horizon-AGN cosmological simulations, when matching sample selection criteria, implying a high probability of both black holes being active simultaneously in late-stage major mergers.
Li et al. (Tue,) studied this question.