The effects of source clustering on weak lensing statistics

TL;DR

This paper examines how source clustering influences weak lensing statistics, especially the local convergence, revealing that higher order moments are affected while variance remains unaffected at leading order.

Contribution

It provides a perturbation theory analysis of source clustering effects on weak lensing convergence, highlighting conditions where these effects are significant.

Findings

Higher order moments are affected by source clustering.

Variance remains unaffected at leading order.

Source clustering effects are negligible for narrow redshift distributions.

Abstract

I investigate the effects of source clustering on the weak lensing statistics, more particularly on the statistical properties of the local convergence, kappa, at large angular scales. The Perturbation Theory approach shows that the variance is not affected by source clustering at leading order but higher order moments such as the third and fourth moments can be. I compute the magnitude of these effects in case of an Einstein-de Sitter Universe for the angular top-hat filtered convergence. In these calculations the so-called Broadhurst and multiple lens coupling effects are neglected. The source clustering effect is found to be particularly important when the redshift distribution is broad enough so that remote background sources can be significantly lensed by closer concentrations of galaxy sources. The source clustering effects are shown to remain negligible, for both the skewness and the kurtosis, when the dispersion of the redshift of the sources is less than about 0.15.