Sanders, D. B. et al. Ultraluminous infrared galaxies and the origin of quasars. Astrophys. J. 325, 74–91 (1988).

Article 
ADS 

Google Scholar
 

Hopkins, P. F., Hernquist, L., Cox, T. J. & Kereš, D. A cosmological framework for the co-evolution of quasars, supermassive black holes, and elliptical galaxies. I. Galaxy mergers and quasar activity. Astrophys. J. Suppl. 175, 356–389 (2008).

Article 
ADS 

Google Scholar
 

Di Matteo, T., Volker, S. & Lars, H. Energy input from quasars regulates the growth and activity of black holes and their host galaxies. Nature 433, 604–607 (2005).

Article 

Google Scholar
 

Park, J., Smith, R. & Yi, S. K. Star formation of merging disk galaxies with AGN feedback effects. Astrophys. J. 845, 128 (2017).

Article 
ADS 

Google Scholar
 

Trinca, A. et al. Episodic super-Eddington accretion as a clue to overmassive black holes in the early universe. Mon. Not. R. Astron. Soc. 552, stag1608 (2026).

Article 

Google Scholar
 

Izquierdo-Villalba, D. et al. Connecting low-redshift LISA massive black hole mergers to the nHz stochastic gravitational wave background. Astron. Astrophys. 686, A183 (2024).

Article 

Google Scholar
 

Maiolino, R. et al. JADES: the diverse population of infant black holes at 4 < z < 11: merging, tiny, poor, but mighty. Astron. Astrophys. 691, A145 (2024).

Article 

Google Scholar
 

Matthee, J. et al. Little Red Dots: an abundant population of faint active galactic nuclei at z ~ 5 revealed by the EIGER and FRESCO JWST surveys. Astrophys. J. 963, 129 (2024).

Article 
ADS 

Google Scholar
 

Green, P. J. et al. SDSS J1254+0846: a binary quasar caught in the act of merging. Astrophys. J. 710, 1578–1588 (2010).

Article 
ADS 

Google Scholar
 

Silverman, J. D. et al. The impact of galaxy interactions on active galactic nucleus activity in zCOSMOS. Astrophys. J. 743, 2 (2011).

Article 
ADS 

Google Scholar
 

Ellison, S. L., Trevor, M. J., Patton, D. R. & Scudder, J. M. Galaxy pairs in the Sloan Digital Sky Survey—VIII. The observational properties of post-merger galaxies. Mon. Not. R. Astron. Soc. 435, 3627–3638 (2013).

Article 
ADS 

Google Scholar
 

Comerford, J. M. et al. Merger-driven fueling of active galactic nuclei: six dual and offset AGNs discovered with Chandra and Hubble Space Telescope observations. Astrophys. J. 806, 219 (2015).

Article 
ADS 

Google Scholar
 

Liu, X. et al. A trio of massive black holes caught in the act of merging. Astrophys. J. 887, 90 (2019).

Article 
ADS 

Google Scholar
 

Blecha, L., Loeb, A. & Narayan, R. Double-peaked narrow-line signatures of dual supermassive black holes in galaxy merger simulations. Mon. Not. R. Astron. Soc. 429, 2594–2616 (2013).

Article 
ADS 

Google Scholar
 

Begelman, M. C., Blandford, R. D. & Rees, M. J. Massive black hole binaries in active galactic nuclei. Nature 287, 307–309 (1980).

Agazie, G. et al. The NANOGrav 15 yr data set: evidence for a gravitational-wave background. Astrophys. J. 951, 8 (2023).

Article 

Google Scholar
 

Koss, M. J. et al. NuSTAR resolves the first dual AGN above 10 keV in SWIFT J2028.5+2543. Astrophys. J. 824, 4 (2016).

Article 
ADS 

Google Scholar
 

Koss, M. J. et al. A population of luminous accreting black holes with hidden mergers. Nature 563, 214–216 (2018).

Article 
ADS 

Google Scholar
 

Ricci, C. et al. A hard X-ray view of luminous and ultra-luminous infrared galaxies in GOALS—I. AGN obscuration along the merger sequence. Mon. Not. R. Astron. Soc. 506, 5935–5950 (2021).

Article 
ADS 

Google Scholar
 

De Rosa, A. et al. The quest for dual and binary supermassive black holes: a multi-messenger view. New Astron. Rev. 86, 101525 (2019).

Article 

Google Scholar
 

Pfeifle, R. W., Weaver, K. A., Secrest, N. J., Rothberg, B. & Patton, D. R. Super-size me: The Big Multi-AGN Catalog (The Big MAC) Data Release 1: The source catalog. Astrophys. J. Suppl. Ser. 281, 25 (2025).

Article 
ADS 

Google Scholar
 

Kayo, I. & Oguri, M. Very small scale clustering of quasars from a complete quasar lens survey. Mon. Not. R. Astron. Soc. 424, 1363–1371 (2012).

Article 
ADS 

Google Scholar
 

Silverman, J. D. et al. Dual supermassive black holes at close separation revealed by the Hyper Suprime-Cam Subaru Strategic Program. Astrophys. J. 899, 154 (2020).

Article 
ADS 

Google Scholar
 

Glikman, E. et al. A candidate dual QSO at Cosmic Noon. Astrophys. J. 951, 18 (2023).

Article 

Google Scholar
 

Chen, Y.-C. et al. A close quasar pair in a disk–disk galaxy merger at z = 2.17. Nature 616, 45–49 (2023).

Article 
ADS 

Google Scholar
 

Mannucci, F. et al. GMP-selected dual and lensed AGNs: selection function and classification based on near-IR colors and resolved spectra from VLT/ERIS, Keck/OSIRIS, and LBT/LUCI. Astron. Astrophys. 680, A53 (2023).

Article 

Google Scholar
 

Shen, Y. et al. A hidden population of high-redshift double quasars unveiled by astrometry. Nat. Astron. 5, 569–574 (2021).

Article 
ADS 

Google Scholar
 

Shen, Y. et al. Statistics of galactic-scale quasar pairs at Cosmic Noon. Astrophys. J. 943, 38 (2023).

Article 
ADS 

Google Scholar
 

Decarli, R. et al. A quasar-galaxy merger at z ~ 6.2: rapid host growth via the accretion of two massive satellite galaxies. Astron. Astrophys. 689, A219 (2024).

Article 

Google Scholar
 

Li, J. et al. Active galactic nuclei and host galaxies in COSMOS-Web. II. First look at the kiloparsec-scale dual and offset AGN population. Astrophys. J. 986, 101 (2025).

Article 
ADS 

Google Scholar
 

Perna, M. et al. GA-NIFS: high number of dual active galactic nuclei at z ~ 3. Astron. Astrophys. 696, A59 (2025).

Article 

Google Scholar
 

Matsuoka, Y. et al. Discovery of merging twin quasars at z = 6.05. Astrophys. J. Lett. 965, L4 (2024).

Article 
ADS 

Google Scholar
 

Izumi, T. et al. Merging gas-rich galaxies that harbor low-luminosity twin quasars at z = 6.05: a promising progenitor of the most luminous quasars. Astrophys. J. 972, 116 (2024).

Article 
ADS 

Google Scholar
 

Übler, H. et al. BlackTHUNDER: evidence of three massive black holes in a z ~ 5 galaxy. Astron. Astrophys. 712, A80 (2026).

Article 

Google Scholar
 

Volonteri, M. et al. Dual AGN in the Horizon-AGN simulation and their link to galaxy and massive black hole mergers, with an excursus on multiple AGN. Mon. Not. R. Astron. Soc. 514, 640–656 (2022).

Article 
ADS 

Google Scholar
 

Civano, F. et al. The Chandra COSMOS Legacy Survey: overview and point source catalog. Astrophys. J. 819, 62 (2016).

Article 
ADS 

Google Scholar
 

Suh, H. et al. A super-Eddington-accreting black hole ~1.5 Gyr after the Big Bang observed with JWST. Nat. Astron. 9, 271 (2025).

Article 
ADS 

Google Scholar
 

Sluse, D. et al. Microlensing of the broad line region in 17 lensed quasars. Astron. Astrophys. 544, A62 (2012).

Article 

Google Scholar
 

Treu, T. & Marshall, P. J. Time delay cosmography. Astron. Astrophys. Rev. 24, 11 (2016).

Article 
ADS 

Google Scholar
 

Comerford, J. et al. Inspiralling supermassive black holes: a new signpost for galaxy mergers. Astrophys. J. 698, 956–965 (2009).

Article 
ADS 

Google Scholar
 

Carilli, C. L. & Walter, F. Cool gas in high-redshift galaxies. Annu. Rev. Astron. Astrophys. 51, 105–161 (2013).

Article 
ADS 

Google Scholar
 

Decarli, R. et al. An ALMA [C II] survey of 27 quasars at z > 5.94. Astrophys. J. 854, 97 (2018).

Article 
ADS 

Google Scholar
 

Decarli, R. & Tanio, D.-S. Infrared fine-structure lines at high redshift. Astron. Astrophys. Rev. 33, 4 (2025).

Article 
ADS 

Google Scholar
 

Neeleman, M. et al. The kinematics of z > 6 quasar host galaxies. Astrophys. J. 911, 141 (2021).

Article 
ADS 

Google Scholar
 

Maiolino, R. et al. Evidence of strong quasar feedback in the early Universe. Mon. Not. R. Astron. Soc. 425, L66 (2012).

Article 
ADS 

Google Scholar
 

Cicone, C. et al. Very extended cold gas, star formation and outflows in the halo of a bright quasar at z > 6. Astron. Astrophys. 574, A14 (2015).

Article 

Google Scholar
 

Wang, F. et al. A spatially resolved [C II] survey of 31 z ~ 7 massive galaxies hosting luminous quasars. Astrophys. J. 968, 9 (2024).

Article 
ADS 

Google Scholar
 

Saeedzadeh, V. et al. Dual active galactic nuclei: precursors of binary supermassive black hole formation and mergers. Astrophys. J. 975, 265 (2024).

Article 
ADS 

Google Scholar
 

Kormendy, J. & Ho, L. C. Coevolution (or not) of supermassive black holes and host galaxies. Annu. Rev. Astron. Astrophys. 51, 511–653 (2013).

Article 
ADS 

Google Scholar
 

Reines, A. E. & Volonteri, M. Relations between central black hole mass and total galaxy stellar mass in the local universe. Astrophys. J. 813, 82 (2015).

Article 
ADS 

Google Scholar
 

Herrera-Camus, R. et al. [C II] 158 μm emission as a star formation tracer. Astrophys. J. 800, 1 (2015).

Article 
ADS 

Google Scholar
 

Loiacono, F. et al. A quasar–galaxy merger at z ~ 6.2: black hole mass and quasar properties from the NIRSpec spectrum. Astron. Astrophys. 685, 121 (2024).

Article 

Google Scholar
 

Chang, S.-J., Gronke, M., Matthee, J. & Mason, C. Impact of resonance, Roman, and Thomson scattering on hydrogen line formation in Little Red Dots. Mon. Not. R. Astron. Soc. 545, staf2131 (2026).

Article 

Google Scholar
 

Greene, J. E. & Ho, L. C. Estimating black hole masses in active galaxies using the Hα emission line. Astrophys. J. 630, 122–129 (2005).

Article 
ADS 

Google Scholar
 

Murphy, K. D. & Yaqoob, T. An X-ray spectral model for Compton-thick toroidal reprocessors. Mon. Not. R. Astron. Soc. 397, 1549–1562 (2009).

Article 
ADS 

Google Scholar
 

Lanzuisi, G. et al. The Chandra COSMOS Legacy Survey: Compton-thick AGN at high redshift. Mon. Not. R. Astron. Soc. 480, 2578–2592 (2018).

Article 
ADS 

Google Scholar
 

Duras, F. et al. Universal bolometric corrections for active galactic nuclei over seven luminosity decades. Astron. Astrophys. 636, A73 (2020).

Article 

Google Scholar
 

McMullin, J. P., Waters, B., Schiebel, D., Young, W. & Golap, K. CASA architecture and applications. Astron. Soc. Pac. Conf. Ser. 376, 127–130 (2007).

ADS 

Google Scholar
 

Zanella, A. et al. The [C II] emission as a molecular gas mass tracer in galaxies at low and high redshifts. Mon. Not. R. Astron. Soc. 481, 1976–1999 (2018).

Article 
ADS 

Google Scholar
 

Madden, S. C. et al. Tracing the total molecular gas in galaxies: [C II] and the CO-dark gas. Astron. Astrophys. 643, A141 (2020).

Article 

Google Scholar
 

Decarli, R. et al. Molecular gas in z ~ 6 quasar host galaxies. Astron. Astrophys. 662, A60 (2022).

Article 

Google Scholar
 

Sommovigo, L. et al. Dust temperature in ALMA [C II]-detected high-z galaxies. Mon. Not. R. Astron. Soc. 503, 4878–4891 (2021).

Article 
ADS 

Google Scholar
 

Pineda, J. L., Langer, W. D., Velusamy, T. & Goldsmith, P. F. A. Herschel [C II] Galactic plane survey. I. The global distribution of ISM gas components. Astron. Astrophys. 554, A103 (2013).

Article 
ADS 

Google Scholar
 

Suh, H. LID-1166 NIRSpec IFU. MAST Archive https://doi.org/10.17909/pvsx-yv31 (2026).

Farina, E. P. et al. The X-shooter/ALMA sample of quasars in the epoch of reionization. II. Black hole masses, Eddington ratios, and the formation of the first quasars. Astrophys. J. 941, 106 (2022).

Article 
ADS 

Google Scholar
 

Suh, H. et al. No significant evolution of relations between black hole mass and galaxy total stellar mass up to z ~ 2.5. Astrophys. J. 889, 32 (2020).

Article 
ADS 

Google Scholar