On scale-dependent cosmic shear systematic effects

T. D. Kitching*, A. N. Taylor, M. Cropper, H. Hoekstra, R. K.E. Hood, R. Massey, S. Niemi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


In this paper, we investigate the impact that realistic scale-dependent systematic effects may have on cosmic shear tomography. We model spatially varying residual galaxy ellipticity and galaxy size variations in weak lensing measurements and propagate these through to predicted changes in the uncertainty and bias of cosmological parameters. We show that the survey strategy - whether it is regular or randomized - is an important factor in determining the impact of a systematic effect: a purely randomized survey strategy produces the smallest biases, at the expense of larger parameter uncertainties, and a very regularized survey strategy produces large biases, but unaffected uncertainties. However, by removing, or modelling, the affected scales (l-modes) in the regular cases the biases are reduced to negligible levels. We find that the integral of the systematic power spectrum is not a good metric for dark energy performance, and we advocate that systematic effects should be modelled accurately in real space, where they enter the measurement process, and their effect subsequently propagated into power spectrum contributions.

Original languageEnglish
Pages (from-to)3319-3332
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Early online date28 Nov 2015
Publication statusPublished - 21 Jan 2016


  • Cosmology: theory
  • Large-scale structure of universe


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