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

Li, Xiangchong; Li, Yin; Massey, Richard

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


Authors

Xiangchong Li

Yin Li



Abstract

Dedicated ‘Stage IV’ observatories will soon observe the entire extragalactic sky, to measure the ‘cosmic shear’ distortion of galaxy shapes by weak gravitational lensing. To measure the apparent shapes of those galaxies, we present an improved version of the Fourier Power Function Shapelets (FPFS) shear measurement method. This now includes analytic corrections for sources of bias that plague all shape measurement algorithms: Including noise bias (due to noise in non-linear combinations of observable quantities) and selection bias (due to sheared galaxies being more or less likely to be detected). Crucially, these analytic solutions do not rely on calibration from external image simulations. For isolated galaxies, the small residual ∼10−3 multiplicative bias and ≲10−4 additive bias now meet science requirements for Stage IV experiments. FPFS also works accurately for faint galaxies and robustly against stellar contamination. Future work will 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.

Citation

Li, X., Li, Y., & Massey, R. (2022). Weak gravitational lensing shear measurement with FPFS: analytical mitigation of noise bias and selection bias. Monthly Notices of the Royal Astronomical Society, 511(4), 4850-4860. https://doi.org/10.1093/mnras/stac342

Journal Article Type Article
Acceptance Date Jan 30, 2022
Online Publication Date Feb 9, 2022
Publication Date 2022-04
Deposit Date May 26, 2022
Publicly Available Date May 26, 2022
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 511
Issue 4
Pages 4850-4860
DOI https://doi.org/10.1093/mnras/stac342

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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. ©: 2021 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.





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