An Extremely Bright QSO at $z=2.89$

Abstract

We report the discovery and confirmation of a bright quasi-stellar object (QSO), 2MASS J13260399+7023462, at $z=2.889$. This QSO is the first spectroscopically confirmed candidate from an ongoing search using the combination of Gaia and WISE photometry to identify bright QSOs at $z>2$, the redshift regime for which the Lyman-$\alpha$ forest is accessible with ground-based facilities. With a Gaia apparent magnitude $G=16.07$, 2MASS J13260399+7023462 is one of the brightest QSOs known at $z>2$, with only 15 currently known brighter QSOs. Given its inferred $M_{1450,AB}$ magnitude and redshift, it is among the most luminous objects in the Universe; the inferred black hole mass and corresponding Eddington ratio are ($2.7 \pm 0.4$) $\times$ 10$^{10}$ M$_{\odot}$ and $1.3 \pm 0.3$, respectively. Follow-up Hubble observations confirm it is not gravitationally lensed.