Source Distributions of Cosmic Shear Surveys in Efficiency Space

Abstract

We show that the lensing efficiency of cosmic shear generically has a simple shape, even in the case of a tomographic survey with badly behaved photometric redshifts. We argue that source distributions for cosmic shear can therefore be more effectively parametrised in ``efficiency space''. Using realistic simulations, we find that the true lensing efficiency of a current cosmic shear survey without disconnected outliers in the redshift distributions can be described to per cent accuracy with only two parameters, and the approach straightforwardly generalises to other parametric forms and surveys. The cosmic shear signal is thus largely insensitive to the details of the source distributions, and the features that matter can be summarised by a small number of suitable efficiency parameters. For the simulated survey, we show that prior knowledge at the 10% level, which is attainable e.g. from photometric redshifts, is enough to marginalise over the efficiency parameters without severely affecting the constraints on the cosmology parameters ${\Omega }_m$ and ${\sigma }_8$.

7 pages, 9 figures; notebook available at https://github.com/cosmiclens/arxiv-efficiency-space; v2: accepted by OJA

References in corpus (3)

• Dark Energy Survey Year 1 Results: Multi-Probe Methodology and Simulated Likelihood Analyses
• The impact of spectroscopic incompleteness in direct calibration of redshift distributions for weak lensing surveys
• The Buzzard Flock: Dark Energy Survey Synthetic Sky Catalogs

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• Dark Energy Survey Year 3 results: Marginalisation over redshift distribution uncertainties using ranking of discrete realisations
• Dark Energy Survey Year 3 Results: Redshift Calibration of the MagLim Lens Sample from the combination of SOMPZ and clustering and its impact on Cosmology
• Constraining the physics of star formation from CIB-cosmic shear cross-correlations
• Combining cosmic shear data with correlated photo-$z$ uncertainties: constraints from DESY1 and HSC-DR1
• The Sensitivity of the Redshift Distribution to Galaxy Demographics
• Mapping Variations of Redshift Distributions with Probability Integral Transforms