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Paper: Gravitational lensing of quasars
Volume: 21, The Space Distribution of Quasars
Page: 304
Authors: Kaiser, Nick; Tribble, Peter
Abstract: Estimates of the lensing optical depth due to individual galaxies can account for the small theta not greater than 2 arcsec splittings, but multi-galaxy mass concentrations are required for the larger splittings. We show that the abundance of these objects matches quite well a simple extrapolation of the X-ray cluster temperature distribution, provided that the mass density profiles of the clusters continue to rise roughly as p inversely as r exp -2 well inside the X-ray core radius. Quasar-galaxy associations, if due to microlensing, provide, in principle, a very clean probe of the mass distribution around galaxies. However, the expected effect, based on conventional models for the mass distribution and intrinsic quasar luminosity function, is about a factor 20 lower than observed. Possible loopholes are considered, but for the most part rejected.
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