A close quasar pair in a disk-disk galaxy merger at z = 2.17

Abstract

Galaxy mergers produce pairs of supermassive black holes (SMBHs), which may be witnessed as dual quasars if both SMBHs are rapidly accreting. The kiloparsec (kpc)-scale separation represents a physical regime sufficiently close for merger-induced effects to be important yet wide enough to be directly resolvable with the facilities currently available. Whereas many kpc-scale dual active galactic nuclei--the low-luminosity counterparts of quasars--have been observed in low-redshift mergers, no unambiguous dual quasar is known at cosmic noon ($z\approx 2$), the peak of global star formation and quasar activity. Here we report multiwavelength observations of SDSS J0749+2255 as a kpc-scale, dual-quasar system hosted by a galaxy merger at cosmic noon ($z=2.17$). We discover extended host galaxies associated with the much brighter compact quasar nuclei (separated by 0.46" or 3.8 kpc) and low-surface-brightness tidal features as evidence for galactic interactions. Unlike its low-redshift and low-luminosity counterparts, SDSS J0749+2255 is hosted by massive compact disk-dominated galaxies. The apparent lack of stellar bulges and the fact that SDSS J0749+2255 already follows the local SMBH mass--host stellar mass relation, suggest that at least some SMBHs may have formed before their host stellar bulges. While still at kpc-scale separations where the host-galaxy gravitational potential dominates, the two SMBHs may evolve into a gravitationally bound binary system in around 0.22 Gyr.

88 pages, 18 figures, 8 tables; published

References in corpus (7)

• Cosmic Star Formation History
• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
• Quasar Quartet Embedded in Giant Nebula Reveals Rare Massive Structure in Distant Universe
• The Sloan Digital Sky Survey Quasar Lens Search. II. Statistical Lens Sample from the Third Data Release
• A Strong X-Ray Flux Ratio Anomaly in the Quadruply Lensed Quasar PG 1115+080
• Opening the era of quasar host studies at high redshift with JWST
• Galaxy pairs in The Three Hundred simulations: a study on the performance of observational pair-finding techniques

Cited by in corpus (10)

• Detection of stellar light from quasar host galaxies at redshifts above 6
• The ultra-dense, interacting environment of a dual AGN at z $\sim$ 3.3 revealed by JWST/NIRSpec IFS
• EIGER V. Characterizing the Host Galaxies of Luminous Quasars at $z\gtrsim 6$
• MUSE adaptive-optics spectroscopy confirms dual active galactic nuclei and strongly lensed systems at sub-arcsec separation
• A Candidate Dual QSO at Cosmic Noon
• Identification of Intermediate-mass Black Hole Candidates Among a Sample of Sd Galaxies
• Quasar Pairs as Large--Scale Structure tracers
• Search for Quasar Pairs with $Gaia$ Astrometric Data. I. Method and Candidates
• Fast, dust-poor outflows in the local candidate dual AGN MCG-03-34-64 observed with VLT/ERIS
• A Population Study for Searching Supermassive Binary Black Holes in Active Galactic Nuclei: Continuum Spectral Features and Periodic Variabilities