Citation:
Date Published:
August 1, 2003Abstract:
We report the discovery of a new gravitationally lensed quasar from theSloan Digital Sky Survey, SDSS J092455.87+021924.9 (SDSS J0924+0219).This object was selected from among known SDSS quasars by an algorithmthat was designed to select another known SDSS lensed quasar (SDSSJ1226-0006A,B). Five separate components, three of which are unresolved,are identified in photometric follow-up observations obtained with theMagellan Consortium's 6.5 m Walter Baade Telescope at Las CampanasObservatory. Two of the unresolved components (designated A and B) areconfirmed to be quasars with z=1.524; the velocity difference is lessthan 100 km s-1 according to spectra taken with the W. M.Keck Observatory's Keck II Telescope at Mauna Kea, Hawaii. A thirdstellar component, designated C, has the colors of a quasar withredshift similar to components A and B. The maximum separation of thepoint sources is 1.78". The other two sources, designated G and D, areresolved. Component G appears to be the best candidate for the lensinggalaxy. Although component D is near the expected position of the fourthlensed component in a four-image lens system, its properties are notconsistent with being the image of a quasar at z~1.5. Nevertheless, theidentical redshifts of components A and B and the presence of componentC strongly suggest that this object is a gravitational lens. Ourobservations support the idea that a foreground object reddens thefourth lensed component and that another unmodeled effect (such asmicro- or millilensing) demagnifies it, but we cannot rule out thepossibility that SDSS J0924+0219 is an example of the relatively rareclass of ``three-component'' lens systems.