Abstract
The z = 1.377, B = 17.0 mag quasar SBS 0909+532 A, B is a double with two images separated by Δθ = 1
107 ± 0006. Because the faint image has an emission line at the same wavelength as the Mg II 2798 Å emission line of the quasar, and it lacks the broad Mg Ib absorption feature expected for a star with the same colors (a K star), we conclude that image B is a quasar with similar redshift to image A. The relative probabilities that the double is the smallest separation (4.7 h-1 kpc for Ω0 = 1) correlated quasar pair or a gravitational lens are ~1:106. If the object is a lens, the mean lens redshift is ⟨zl⟩ = 0.5 with 90% confidence bounds of 0.18 < zl < 0.83 for Ω0 = 1. If the lens is an elliptical galaxy, we expect it to be brighter than I < 19.5 mag. The broadband flux ratio varies with wavelength, with ΔI = 0.31, ΔR = 0.58, and ΔB = 1.29 magnitudes, which is difficult to reconcile with the lensing hypothesis.
Export citation and abstract BibTeX RIS
Footnotes
- *
Observations reported here were obtained, in part, at MDM Observatory, a consortium of the University of Michigan, Dartmouth College, and the Massachusetts Institute of Technology.
- **
This research based in part on observations made with the Multiple Mirror Telescope, a joint facility of the Smithsonian Institution and the University of Arizona.
- ***
This research made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, Caltech, under contract with the National Aeronautics and Space Administration.
- ****
We have made use in part of finder chart(s) obtained using the Guide Stars Selection System Astrometric Support Program developed at the Space Telescope Science Institute (STScI is operated by the Association of Universities for Research in Astronomy, Inc., for NASA).