radioGREAT - a radio GRavitational lEnsing Accuracy Testing Challenge

Introduction

This is the website for the radioGREAT challenge, a blind data analysis challenge to test the ability of algorithms to do cosmological weak lensing with data from radio interferometers.

The Square Kilometre Array (SKA) has the potential to be competitive with other large facilities such as Euclid, LSST and WFIRST in constraining the Dark Energy equation of state to the 'Stage IV' level specified by the Dark Energy Task Force by measuring the weak gravitational lensing of background galaxies.

Measuring a weak lensing signal in the radio presents a number of unique advantages, probing higher redshifts than optical and near-IR weak lensing and in using novel techniques to overcome a number of astrophysical systematic effects.

However, extracting a weak lensing signal from data is hard, requiring the measurement of galaxy morphologies to exquisite accuracy. The aim of radioGREAT is to both provide a benchmark of current methods for inferring cosmic shear from radio data and spur interest in development of new methods. We will provide high quality simulated data sets of observations of fields of radio galaxies for participants to use to attempt to blindly measure the applied shear.

In order to be as inclusive as possible, we expect to provide both image and visibility-plane versions of the data sets, with fiducial algorithms for both imaging and image-plane shape measurement available to participants.