WFI J2026-4536 and WFI J2033-4723: Two New Quadruple Gravitational Lenses

Abstract

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 PG1115-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 = 17.9, and a more complicated environment of at least six galaxies within 20". The primary lensing galaxies are detected for both systems after PSF subtraction. Several of the broadband flux ratios for the two lenses show a strong (0.1-0.4 mags) 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 three 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 1-2 weeks for the long delay, but are longer for WFI J2033-4723, ranging from 1-2 months. Both systems hold promise for future monitoring campaigns aimed at microlensing or time delay studies.