Search for Kiloparsec-scale Dual Active Galactic Nuclei at Low Redshift

Research on dual AGNs (Active Galactic Nuclei) is crucial for understanding the formation, growth, and evolution of galaxies and supermassive black holes (SMBHs). However, the current number of identified dual AGNs remains scarce, which limits our understanding of galaxy mergers, the growth of SMBH pairs, and the prediction and detection of low-frequency gravitational waves. A total of 187 new dual AGNs, 4 triple AGN systems, and 1 quadruple AGN system were identified based on the Million Quasars Catalog. All of these multiple AGN systems have low redshifts ($z <$ 0.5), with projected distance ($r_{\rm p}$) between members less than 100 kpc and line-of-sight velocity differences ($\Delta v$) smaller than 600 km/s. This sample complements existing low-redshift dual AGN samples and provides valuable insights into AGN triggering mechanisms and the evolution of SMBH pairs. A visual inspection of the optical and infrared images of the identified samples reveals that approximately 24% of the dual AGN systems exhibit clear tidal features. Statistical analysis of their redshift, projected distance, and line-of-sight velocity difference indicates that the number of dual AGN increases with decreasing redshift, and that most $\Delta v$ values are distributed below 400 km/s. The number of dual AGN systems with tidal features is relatively small in larger projected distances, with only one system found in (60$-$65) $ h^{-1}_{70} \; \text{kpc} $. As the projected separation decreases, the number of such systems increases, reaching a peak of 10 cases in (10$-$15) $ h^{-1}_{70} \; \text{kpc} $, and then gradually decreases in smaller scales.