Discovery of four doubly imaged quasar lenses from the Sloan digital sky survey

Abstract

We report the discovery of four doubly imaged quasar lenses. All the four systems are selected as lensed quasar candidates from the Sloan Digital Sky Survey data. We confirm their lensing hypothesis with additional imaging and spectroscopic follow-up observations. The discovered lenses are SDSS J0743+2457 with the source redshift zs = 2.165, the lens redshift zl= 0.381, and the image separation = 1.″034, SDSS J1128+2402 with z s = 1.608 and = 0.″844, SDSS J1405+0959 with zs = 1.810, zl 0.66, and = 1.″978, and SDSS J1515+1511 with z s = 2.054, zl = 0.742, and = 1.″989. It is difficult to estimate the lens redshift of SDSS J1128+2402 from the current data. Two of the four systems (SDSS J1405+0959 and SDSS J1515+1511) are included in our final statistical lens sample to derive constraints on dark energy and the evolution of massive galaxies. © 2014. The American Astronomical Society. All rights reserved..