Gaia Astrometry Confirms Six Dual Quasars Including z~3.1 System, Tightening SMBH Binary Formation Constraints
Gaia-enabled selection plus targeted spectroscopy uncovered six dual quasars, one at z~3.1, plus three projections, directly constraining the sub-10 kpc black-hole pairing phase. The work highlights how astrometric pre-filtering overcomes fiber-collision biases in earlier surveys. Small sample size remains the primary limit on merger-rate inferences.
The key limitation remains small-number statistics and incomplete redshift coverage for the faintest companions; a statistically robust measurement of the dual fraction at z>2 will require a factor-of-five increase in confirmed systems, achievable only once 4MOST and DESI-II allocate dedicated fibers to Gaia-selected pairs.
Chen et al.: Dedicated 4MOST fibers on 200 additional Gaia candidates will yield at least 25 new dual quasars above z=2 by end of 2028
Sources (3)
- [1]Primary Source(https://arxiv.org/abs/2607.00093)
- [2]Supporting Source(https://arxiv.org/abs/2305.02309)
- [3]Supporting Source(https://iopscience.iop.org/article/10.3847/1538-4357/acd3f0)