Maximum-entropy weak lens reconstruction: improved methods and application to data
Abstract
We develop the maximum-entropy weak shear mass reconstruction method presented in earlier papers by taking each background galaxy image shape as an independent estimator of the reduced shear field and incorporating an intrinsic smoothness into the reconstruction. The characteristic length scale of this smoothing is determined by Bayesian methods. Within this algorithm the uncertainties due to the intrinsic distribution of galaxy shapes are carried through to the final mass reconstruction, and the mass within arbitrarily shaped apertures can be calculated with corresponding uncertainties. We apply this method to two clusters taken from N-body simulations using mock observations corresponding to Keck LRIS and mosaiced HST WFPC2 fields. We demonstrate that the Bayesian choice of smoothing length is sensible and that masses within apertures (including one on a filamentary structure) are reliable. We apply the method to data taken on the cluster MS1054-03 using the Keck LRIS (Clowe et al. 2000) and HST (Hoekstra et al. 2000), finding results in agreement with this previous work; we also present reconstructions with optimal smoothing lengths, and mass estimates which do not rely on any assumptions of circular symmetry. The code used in this work (LensEnt2) is available from http://www.mrao.cam.ac.uk/projects/lensentKeywords
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