Beyond the Thin Lens Approximation
Abstract
Description
We obtain analytic formulae for the null geodesics of Friedmann-Lema\^ıtre-Robertson-Walker spacetimes with scalar perturbations in the longitudinal gauge. We use these to provide a rigorous derivation of the cosmological lens equation. We obtain an expression for the magnification of a bundle of light rays in these spacetimes without restriction to static or thin lens scenarios. We show how the usual magnification matrix naturally emerges in the appropriate limits.
Submitted to ApJl, 9 pages plus one figure (plain TeX)
Submitted to ApJl, 9 pages plus one figure (plain TeX)