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Precision calculations of the cosmic shear power spectrum projection

Kilbinger, M, Heymans, C, Asgari, M, Joudaki, S, Schneider, P, Simon, P, Van Waerbeke, L, Harnois-Déraps, J, Hildebrandt, H, Köhlinger, F, Kuijken, K and Viola, M (2017) Precision calculations of the cosmic shear power spectrum projection. Monthly Notices of the Royal Astronomical Society, 472 (2). pp. 2126-2141. ISSN 0035-8711

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Abstract

We compute the spherical-sky weak-lensing power spectrum of the shear and convergence. We discuss various approximations, such as flat-sky, and first- and second-order Limber equations for the projection. We find that the impact of adopting these approximations is negligible when constraining cosmological parameters from current weak-lensing surveys. This is demonstrated using data from the Canada–France–Hawaii Telescope Lensing Survey. We find that the reported tension with Planck cosmic microwave background temperature anisotropy results cannot be alleviated. For future large-scale surveys with unprecedented precision, we show that the spherical second-order Limber approximation will provide sufficient accuracy. In this case, the cosmic-shear power spectrum is shown to be in agreement with the full projection at the sub-percent level for ℓ > 3, with the corresponding errors an order of magnitude below cosmic variance for all ℓ. When computing the two-point shear correlation function, we show that the flat-sky fast Hankel transformation results in errors below two percent compared to the full spherical transformation. In the spirit of reproducible research, our numerical implementation of all approximations and the full projection are publicly available within the package NICAEA at http://www.cosmostat.org/software/nicaea.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: 0201 Astronomical and Space Sciences
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press (OUP)
Date Deposited: 22 Jul 2020 10:49
Last Modified: 22 Jul 2020 11:00
DOI or Identification number: 10.1093/mnras/stx2082
URI: https://researchonline.ljmu.ac.uk/id/eprint/13346

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