Do Quasars Lens Quasars?
arXiv:astro-ph/9612077 · doi:10.1086/310505
Abstract
If the unexpectedly high frequency of quasar pairs with very different component redshifts is due to the lensing of a population of background quasars by the foreground quasar, typical lens masses must be $\sim10^{12}M_{\sun}$ and the sum of all such quasar lenses would have to contain times the closure density of the Universe. It then seems plausible that a very high fraction of all $\sim10^{12} M_{\sun}$ gravitational lenses with redshifts contain quasars. Here I propose that these systems have evolved to form the present population of massive galaxies with M and $M >5\times10^{11} M_{\sun}$.
6 pages, aas style, ams symbols, ApJL (accepted)