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Arxiv: VODKA-JWST: Synchronized growth of two SMBHs in a massive gas disk? A 3.8 kpc separation dual quasar at cosmic noon with JWST NIRSpec IFU Published: 3/13/2024 12:19:48 AM Updated: 3/13/2024 12:19:48 AM

Paper abstract: The search for dual supermassive black holes (SMBHs) is of immense interestin modern astrophysics. Galaxy mergers may be an important route to fuel and toproduce SMBH pairs. Actively accreting SMBH pairs can be observed as a dualquasar, which are vital probes of SMBH growth. Gaia observations have enabled anovel technique to systematically search for such dual quasars at previouslyunreachable sub-kpc scales, based on the small jitters of the light centroid asthe two quasars vary stochastically. Here we present the first detailed studyof a 0.46'', 3.8 kpc separation, VODKA-selected dual quasar, J0749+2255, atz=2.17 using JWST/NIRSpec integral field unit spectroscopy. This is one ofthe most distant, small separation dual quasars identified today. Dual quasarsat cosmic noon are not well characterized. We detect the faint ionized gas ofthe host galaxy, best traced by the narrow \ha\ emission. Line ratiodiagnostics show a mix of ionization from the two quasars and intense starformation. The spatially-resolved spectra of the two quasars suggest that theyhave very similar black hole properties (two M_{BH}~ 10^9\\textrm{M}_{\odot} with large Eddington ratio reaching L/L_{Edd}~0.2)hinting at the possible synchronized growth and accretion from the same gassupply. Surprisingly, the ionized gas kinematics suggest an extended, rotatingdisk rather than a disturbed system that would be expected in a major gas-richgalaxy merger. While it is unclear if J0749+2255 is representative of the dualquasar evolution, the observations with JWST revealed a major puzzle. It wouldbe interesting to see what observations of other dual quasars will show.