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arXiv · 1611.04954

The Limits of Cosmic Shear

Thomas D. Kitching·Justin Alsing·Alan F. Heavens·Raul Jimenez·Jason D. McEwen·Licia Verde
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Abstract

In this paper we discuss the commonly-used limiting cases, or approximations, for two-point cosmic shear statistics. We discuss the most prominent assumptions in this statistic: the flat-sky (small angle limit), the Limber (Bessel-to-delta function limit) and the Hankel transform (large l-mode limit) approximations; that the vast majority of cosmic shear results to date have used simultaneously. We find that the combined effect of these approximations can suppress power by >1% on scales of l<40. A fully non-approximated cosmic shear study should use a spherical-sky, non-Limber-approximated power spectrum analysis; and a transform involving Wigner small-d matrices in place of the Hankel transform. These effects, unaccounted for, would constitute at least 11% of the total budget for systematic effects for a power spectrum analysis of a Euclid-like experiment; but they are unnecessary.

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Thomas D. Kitching, Justin Alsing, Alan F. Heavens, Raul Jimenez, Jason D. McEwen, Licia Verde. 2017-05-03. The Limits of Cosmic Shear. https://doi.org/10.1093/mnras%2Fstx1039

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