Magnification as a Tool in Weak Lensing

TL;DR

This paper proposes using galaxy size and flux measurements, in addition to shape data, to calibrate errors in weak lensing surveys, leading to improved constraints on cosmological parameters like dark energy.

Contribution

It introduces a novel method of using galaxy magnification effects to calibrate measurement errors in weak lensing surveys, enhancing the robustness of cosmological inferences.

Findings

Improved calibration of shear measurements using galaxy size and flux data.

Tighter constraints on dark energy parameters.

Enhanced robustness of weak lensing analysis.

Abstract

Weak lensing surveys exploit measurements of galaxy ellipticities. These measurements are subject to errors which degrade the cosmological information that can be extracted from the surveys. Here we propose a way of using the galaxy data themselves to calibrate the measurement errors. In particular, the cosmic shear field, which causes the galaxies to appear elliptical, also changes their sizes and fluxes. Information about the sizes and fluxes of the galaxies can be added to the shape information to obtain more robust information about the cosmic shear field. The net result will be tighter constraints on cosmological parameters such as those which describe dark energy.