Weak gravitational lensing shear measurement with FPFS: analytical mitigation of noise bias and selection bias

4 Oct 2021  ·  Xiangchong Li, Yin Li, Richard Massey ·

We present the second version of the Fourier Power Function Shapelets (FPFS) shear estimator. We derive an analytic correction for nonlinear noise bias that is accurate to second order... In addition, we derive analytic corrections for selection biases caused by binning galaxies according to both sheared and noisy quantities. This improves the accuracy of the estimator by one order of magnitude. For isolated galaxies, the residual $\sim$$10^{-3}$ multiplicative bias and $\lesssim$$10^{-4}$ additive bias now meet science requirements for Stage IV experiments without relying on calibration from external image simulations. Future work will next focus on deblending overlapping galaxies. The code used for this paper can process $>$$1000$ galaxy images per CPU~second and is available from https://github.com/mr-superonion/FPFS . read more

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Cosmology and Nongalactic Astrophysics Instrumentation and Methods for Astrophysics