CFHTLenS: The Canada-France-Hawaii Telescope Lensing Survey

TL;DR

The CFHTLenS survey provides a precise weak gravitational lensing measurement over 154 square degrees, with improved data analysis techniques ensuring robust cosmic shear signals for cosmological studies.

Contribution

This work introduces an enhanced analysis pipeline and a novel contamination identification method, improving the accuracy and reliability of weak lensing measurements from the CFHT data.

Findings

Robust cosmic shear signal detected across the survey area

Development of a new contamination identification technique

Provision of a science-ready shear and redshift catalogue

Abstract

We present the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS) that accurately determines a weak gravitational lensing signal from the full 154 square degrees of deep multi-colour data obtained by the CFHT Legacy Survey. Weak gravitational lensing by large-scale structure is widely recognised as one of the most powerful but technically challenging probes of cosmology. We outline the CFHTLenS analysis pipeline, describing how and why every step of the chain from the raw pixel data to the lensing shear and photometric redshift measurement has been revised and improved compared to previous analyses of a subset of the same data. We present a novel method to identify data which contributes a non-negligible contamination to our sample and quantify the required level of calibration for the survey. Through a series of cosmology-insensitive tests we demonstrate the robustness of the resulting cosmic shear signal, presenting a science-ready shear and photometric redshift catalogue for future exploitation.