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

Nicholas D. Morgan, John A.R. Caldwell, Paul L. Schechter, Alan Dressler, Eiichi Egami, Hans Walter Rix

Research output: Contribution to journalReview articlepeer-review

72 Scopus citations


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 ≈ 17.9, and a more complicated environment of at least six galaxies within 20″. 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.

Original languageEnglish (US)
Pages (from-to)2617-2630
Number of pages14
JournalAstronomical Journal
Issue number5 1781
StatePublished - May 2004


  • Gravitational lensing

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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