Euclid preparation: VI. Verifying the Performance of Cosmic Shear Experiments

TL;DR

This paper develops an end-to-end pipeline to assess how systematic biases like CTI and PSF modeling uncertainties affect cosmological parameter inference from cosmic shear data, specifically for Euclid.

Contribution

It introduces a comprehensive method to propagate galaxy-level biases through to cosmological parameters, enabling quantification of systematic impacts on Euclid-like surveys.

Findings

Biases from CTI and PSF uncertainties can be corrected to acceptable levels.

The pipeline quantifies how systematic errors influence dark energy parameter estimates.

Systematic effects significantly impact cosmic shear measurements if uncorrected.

Abstract

Our aim is to quantify the impact of systematic effects on the inference of cosmological parameters from cosmic shear. We present an end-to-end approach that introduces sources of bias in a modelled weak lensing survey on a galaxy-by-galaxy level. Residual biases are propagated through a pipeline from galaxy properties (one end) through to cosmic shear power spectra and cosmological parameter estimates (the other end), to quantify how imperfect knowledge of the pipeline changes the maximum likelihood values of dark energy parameters. We quantify the impact of an imperfect correction for charge transfer inefficiency (CTI) and modelling uncertainties of the point spread function (PSF) for Euclid, and find that the biases introduced can be corrected to acceptable levels.