We report the discovery of the new double quasar CTQ 839 .
This B = 18.3 , radio quiet quasar pair is separated by 2 \farcs 1 in BRI & H filters with magnitude differences of \Delta m _ { B } = 2.5 , \Delta m _ { R } = \Delta m _ { I } = 1.9 , and \Delta m _ { H } = 2.3 .
Spectral observations reveal both components to be z = 2.24 quasars , with relative redshifts that agree at the 100 \mbox { km s } ^ { -1 } level , but exhibit pronounced differences in the equivalent widths of related emission features , as well as an enhancement of blue continuum flux in the brighter component as compared to the fainter component longward of the Ly \alpha emission feature .
In general , similar redshift double quasars can be the result of a physical binary pair , or a single quasar multiply imaged by gravitational lensing .
Empirical PSF subtraction of R and H band images of CTQ 839 reveal no indication of a lensing galaxy , and place a detection limit of R = 22.5 and H = 17.4 for a third component in the system .
For an Einstein-de Sitter cosmology and SIS model , the R band detection limit constrains the characteristics of any lensing galaxy to z _ { l } \gtrsim 1 with a corresponding luminosity of L \gtrsim 5 L _ { * } , while an analysis based on the redshift probability distribution for the lensing galaxy argues against the existence of a z _ { l } \gtrsim 1 lens at the 2 \sigma level .
A similar analysis for a \Lambda dominated cosmology , however , does not significantly constrain the existence of any lensing galaxy .
The broadband flux differences , spectral dissimilarities , and failure to detect a lensing galaxy make the lensing hypothesis for CTQ 839 unlikely .
The similar redshifts of the two components would then argue for a physical quasar binary .
At a projected separation of 8.3 h ^ { -1 } kpc ( \Omega _ { m } = 1 ) , CTQ 839 would be the smallest projected separation binary quasar currently known .