A fully data-driven algorithm for accurate shear estimation

TL;DR

This paper presents a fully data-driven method for accurate shear estimation in weak lensing, effectively handling anisotropic PSF effects and meeting upcoming survey requirements.

Contribution

It introduces a novel data-driven shear estimation algorithm based on MetaDetection that remains unbiased despite PSF anisotropy, improving accuracy in weak lensing measurements.

Findings

Unbiased shear estimates achieved from observed data alone.

Method remains effective under realistic anisotropic PSF conditions.

Approach meets the precision requirements of future surveys.

Abstract

Weak lensing by large-scale structure is a powerful probe of cosmology if the apparent alignments in the shapes of distant galaxies can be accurately measured. We study the performance of a fully data-driven approach, based on MetaDetection, focusing on the more realistic case of observations with an anisotropic PSF. Under the assumption that PSF anisotropy is the only source of additive shear bias, we show how unbiased shear estimates can be obtained from the observed data alone. To do so, we exploit the finding that the multiplicative shear bias obtained with MetaDetection is nearly insensitive to the PSF ellipticity. In practice, this assumption can be validated by comparing the empirical corrections obtained from observations to those from simulated data. We show that our data-driven approach meets the stringent requirements for upcoming space and ground-based surveys, although further optimisation is possible.