Journal
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 502, Issue 3, Pages 4048-4063Publisher
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stab211
Keywords
gravitational lensing: weak; methods: observational; cosmology: observations
Categories
Funding
- Netherlands Organisation for Scientific Research (NWO) [639.043.512]
- National Science Foundation [1258333]
- Department of Energy [DE-AC02-76SF00515]
- SLAC National Accelerator Laboratory
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METACALIBRATION is a state-of-the-art technique for measuring weak gravitational lensing shear, but fitting undersampled galaxy images with this technique may introduce aliasing effects leading to significant shear biases.
METACALIBRATION is a state-of-the-art technique for measuring weak gravitational lensing shear from well-sampled galaxy images. We investigate the accuracy of shear measured with METACALIBRATION from fitting elliptical Gaussians to undersampled galaxy images. In this case, metacalibration introduces aliasing effects leading to an ensemble multiplicative shear bias about 0.01 for Euclid and even larger for the Roman Space Telescope, well exceeding the missions' requirements. We find that this aliasing bias can be mitigated by computing shapes from weighted moments with wider Gaussians as weight functions, thereby trading bias for a slight increase in variance of the measurements. We show that this approach is robust to the point-spread function in consideration and meets the stringent requirements of Euclid for galaxies with moderate to high signal-to-noise ratios. We therefore advocate metacalibration as a viable shear measurement option for weak lensing from upcoming space missions.
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