Shear Recovery Accuracy in Weak-Lensing Analysis with the Elliptical Gauss-Laguerre Method

Abstract

We implement the Elliptical Gauss-Laguerre (EGL) galaxy-shape measurement method proposed by Bernstein & Jarvis (2002) and quantify the shear recovery accuracy in weak lensing analysis. This method uses a deconvolution fitting scheme to remove the effects of the point-spread function (PSF). The test simulates >10^7 noisy galaxy images convolved with anisotropic PSFs, and attempts to recover an input shear. The tests are designed to be immune to shape noise, selection biases, and crowding. The systematic error in shear recovery is divided into two classes, calibration (multiplicative) and additive, with the latter arising from PSF anisotropy. At S/N > 50, the deconvolution method measures the galaxy shape and input shear to ~ 1% multiplicative accuracy, and suppresses > 99% of the PSF anisotropy. These systematic errors increase to ~ 4% for the worst conditions, with poorly resolved galaxies at S/N ~ 20. The EGL weak lensing analysis has the best demonstrated accuracy to date, sufficient for the next generation of weak lensing surveys.