WFI J2026-4536 and WFI J2033-4723: Two new quadruple gravitational lenses

Morgan, ND; Caldwell, JAR; Schechter, PL; Dressler, A; Egami, E; Rix, HW
2004
ASTRONOMICAL JOURNAL
We report the discovery of two new gravitationally lensed quasars, WFI J2026-4536 and WFI J2033-4723, at respective source redshifts of z = 2.23 and z = 1.66. Both systems are quadruply imaged and have similar PG 1115 - like image configurations. WFI J2026 - 4536 has a maximum image separation of 1."4, a total brightness of g = 16.5, and a relatively simple lensing environment, while WFI J2033 - 4723 has a maximum image separation of 2."5, an estimated total brightness of g approximate to 17.9, and a more complicated environment of at least six galaxies within 2000. The primary lensing galaxies are detected for both systems after point-spread function subtraction. Several of the broadband flux ratios in these systems show a strong (0.1 - 0.4 mag) trend with wavelength, suggesting either microlensing or differential extinction through the lensing galaxy. For WFI J2026 - 4536, the total quasar flux has dimmed by 0.1 mag in the blue but only half as much in the red over 3 months, suggestive of microlensing-induced variations. For WFI J2033 - 4723, resolved spectra of some of the quasar components reveal emission-line flux ratios that agree better with the macromodel predictions than either the broadband or continuum ratios, also indicative of microlensing. The predicted differential time delays for WFI J2026 - 4536 are short, ranging from 1 to 2 weeks for the long delay, but are longer for WFI J2033 - 4723, ranging from 1 to 2 months. Both systems hold promise for future monitoring campaigns aimed at microlensing or time delay studies.