Removing the Impact of Correlated PSF Uncertainties in Weak Lensing

TL;DR

This paper introduces a statistical method to correct for correlated PSF uncertainties in weak lensing measurements, improving the accuracy of cosmic shear analysis without relying on specific PSF or galaxy models.

Contribution

A novel statistical correction technique that mitigates the impact of correlated PSF fluctuations on weak lensing signals, independent of PSF or galaxy morphology assumptions.

Findings

Effective reduction of PSF fluctuation contamination in CFHTLenS data

Improved accuracy in cosmic shear correlation functions

Method applicable to future weak lensing surveys

Abstract

Accurate reconstruction of the spatial distributions of the Point Spread Function (PSF) is crucial for high precision cosmic shear measurements. Nevertheless, current methods are not good at recovering the PSF fluctuations of high spatial frequencies. In general, the residual PSF fluctuations are spatially correlated, therefore can significantly contaminate the correlation functions of the weak lensing signals. We propose a method to correct for this contamination statistically, without any assumptions on the PSF and galaxy morphologies or their spatial distribution. We demonstrate our idea with the data from the W2 field of CFHTLenS.