We present the second report of our systematic search for strongly lensed quasars from the data of the Sloan Digital Sky Survey (SDSS). From extensive follow-up observations of 136 candidate objects, we find 36 lenses in the full sample of 77,429 spectroscopically confirmed quasars in the SDSS Data Release 5. We then define a complete sample of 19 lenses, including 11 from our previous search in the SDSS Data Release 3, from the sample of 36,287 quasars with i< 19.1 in the redshift range 0.6 < z < 2.2, where we require the lenses to have image separations of 1″ < 0 < 20″ and i-band magnitude differences between the two images smaller than 1.25 mag. Among the 19 lensed quasars, three have quadruple-image configurations, while the remaining 16 show double images. This lens sample constrains the cosmological constant to be ωa = 0.84+0.06-0.08(stat.)+00.097(syst.) assuming a flat universe, which is in good agreement with other cosmological observations. We also report the discoveries of seven binary quasars with separations ranging from 1/.'1to16'./6, which are identified in the course of our lens survey. This study concludes the construction of our statistical lens sample in the full SDSS-I data set.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
- Cosmology: Observations
- Gravitational lensing: Strong
- Quasars: General