A Weak Lensing Detection of the Cosmological Distance-Redshift Relation Behind Three Massive Clusters

TL;DR

This study measures the weak lensing amplitude as a function of redshift behind three massive galaxy clusters to probe cosmic geometry, demonstrating consistency with cosmological models and potential for future surveys to constrain dark energy.

Contribution

It provides the first measurement of the distance-redshift relation using weak lensing behind multiple clusters, offering a model-independent approach to cosmic geometry.

Findings

Weak lensing amplitude increases with source distance as predicted.

Results are consistent with cosmological models for the deepest dataset.

Scaling to larger surveys can improve constraints on dark energy.

Abstract

The amplitude of weak lensing should increase with source distance, rising steeply behind a lens and saturating at high redshift, providing a model-independent means of measuring cosmic geometry. We measure the amplitude of weak lensing with redshift for three massive clusters, A370 (z=0.375), ZwCl0024+17 (z=0.395) and RXJ1347-11 (z=0.451), using deep, three-colour Subaru imaging. We define the depth of lensed populations with reference to the COSMOS and GOODS fields, providing a consistency check of photo-z estimates over a wide range of redshift and magnitude. The predicted distance-redshift relation is followed well for the deepest dataset, A370, for a wide range of cosmologies, and is consistent with less accurate data for the other two clusters. Scaling this result to a new survey of ~25 massive clusters should provide a useful cosmological constraint on w, complementing existing techniques, with distance measurements covering the untested redshift range, 1<z<5.