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Paper: Evidence for Dust in Gravitational Lenses
Volume: 156, Highly Redshifted Radio Lines
Page: 159
Authors: Rhoads, J. E.; Malhotra, S.; Turner, E. L.
Abstract: In a near-infrared survey of known lensed systems we find that the lensed systems identified in radio and infrared searches have redder optical-IR colors than optically selected ones. This could be due to a bias against selecting extincted and reddened quasars in the optical surveys, or due to the differences in the intrinsic colors of optical and radio quasars. Comparison of the radio-selected lensed and unlensed quasars shows that the lensed ones have redder colors. We therefore conclude that at least part of the color difference between the two lens samples is due to dust in the lensing galaxy. Extinction by dust in lenses could hide the large number of lensed systems predicted for universe with a large value of the cosmological constant Lambda. These results substantially weaken the strongest constraint on models with a large cosmological constant. They also raise the prospect of using gravitational lenses to study the interstellar medium in high redshift galaxies. (A more complete discussion of this work has been published by Malhotra, Rhoads, & Turner [1997] in the Monthly Notices of the Royal Astronomical Society, vol. 288, p. 138.)
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