Weak Lensing Mass Calibration with Shear and Magnification

TL;DR

This paper demonstrates that combining shear and magnification measurements in weak lensing improves mass calibration precision by up to 50%, while also enabling systematic error cross-checks.

Contribution

It introduces a joint analysis of shear and magnification, including size effects, to enhance weak lensing mass calibration accuracy and systematic validation.

Findings

Joint shear and magnification improve mass estimate precision by 40-50%.

Combining probes enables residual systematic checks at a few percent level.

Results are robust across different survey assumptions.

Abstract

We study how joint shear and magnification measurements improve the statistical precision of weak lensing mass calibration experiments, relative to standard shear-only analysis. For our magnification measurements, we consider not only the impact of lensing on the source density of galaxies, but also the apparent increase in source sizes. The combination of all three lensing probes - density, size, and shear - can improve the statistical precision of mass estimates by as much as 40% - 50%. This number is insensitive to survey assumptions, though it depends on the degree of knowledge of the parameters controlling the magnification measurements, and on the value of the parameter q that characterizes the response of the source population to magnification. Furthermore, the combination of magnification and shear allows for powerful cross-checks on residual systematics (such as point spread function corrections) at the few percent level.