Characterizing the Shapes of Galaxy Clusters Using Moments of the Gravitational Lensing Shear

We explore the use of the tangential component of weak lensing shear to characterize the ellipticity of clusters of galaxies. We introduce an ellipticity estimator, and quantify its properties for isolated clusters from ΛCDM N-body simulations. We compare the N-body results to results from smooth analytic models. The expected distribution of the estimator for mock observations is presented, and we show how this distribution is impacted by contaminants such as noise, line of sight projections, and misalignment of the central galaxy used to determine the orientation of the triaxial halo. We examine the radial profile of the estimator and discuss tradeoffs in the observational strategy to determine cluster shape.