Beyond the Thin Lens Approximation

Ted Pyne; Mark Birkinshaw

doi:10.1086/176791

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arXiv · astro-ph/9504060

Beyond the Thin Lens Approximation

Ted Pyne·Mark Birkinshaw

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Abstract

We obtain analytic formulae for the null geodesics of Friedmann-Lema\^ıtre-Robertson-Walker spacetimes with scalar perturbations in the longitudinal gauge. From these we provide a rigorous derivation of the cosmological lens equation, and obtain an expression for the magnification of a bundle of light rays without restriction to static or thin lens scenarios. We show how the usual magnification matrix naturally emerges in the appropriate limits.

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Ted Pyne, Mark Birkinshaw. 1995-04-19. Beyond the Thin Lens Approximation. https://doi.org/10.1086/176791

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