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Weak lensing ellipticities in a strong lensing regime
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http://hdl.handle.net/1860/1915
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| Title: | Weak lensing ellipticities in a strong lensing regime |
| Authors: | Goldberg, David
Massey, Richard |
| Keywords: | Gravitational Lensing |
| Issue Date: | 11-Sep-2007 |
| Publisher: | American Astronomical Society |
| Citation: | Astrophysical Journal |
| Abstract: | It is now routine to measure the weak gravitational lensing shear signal from the mean ellipticity
of distant galaxies. However, conversion between ellipticity and shear assumes local linearity
of the lensing potential (i.e. that the spatial derivatives of the shear are small), and this condition
is not satisfied in some of the most interesting regions of the sky. We extend a derivation of lensing
equations to include higher order terms, and assess the level of biases introduced by assuming
that first-order weak lensing theory holds in a relatively strong shear regime. We find that, even
in a worst-case scenario, a fully linear analysis is accurate to within 1% outside ∼ 1.07 times
the Einstein radius of a lens. The effect should therefore have little impact on measurements of
overall cluster masses for the foreseeable future. However, at the level of accuracy demanded by
upcoming lensing surveys, such biases ought to be considered in measurements of the inner slope
of cluster mass distributions and the small-scale end of the mass power spectrum. Both of these
are central in determining the relationship between baryonic and dark matter. |
| URI: | http://arxiv.org/abs/0709.1479v1
http://hdl.handle.net/1860/1915 |
| Appears in Collections: | Faculty Research and Publications (Physics)
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