Analytic expressions for mean magnification by a quadrupole gravitational lens
Preprint
- 28 May 2002
Abstract
We derive an analytic expression for the mean magnification due to strong gravitational lensing, using a simple lens model, a singular isothermal sphere embedded in an external shear field. We compute separate expressions for 2-image and 4-image lensing. For 4-image lensing, the mean magnification takes a particularly simple form: _4 = 3.6/(gamma*(1-gamma^2)), where gamma is the external shear. We compare our analytic results to a numerical evaluation of the full magnification distribution. The results can be used to understand the magnification bias that favors the discovery of four-image systems over two-image systems in flux-limited lens surveys.Keywords
All Related Versions
- Version 1, 2002-05-28, ArXiv
- Published version: The Astrophysical Journal, 577 (1), 51.
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