Weak Gravitational Lensing Shear Estimation with Metacalibration for the Roman High-Latitude Imaging Survey

Abstract

We investigate the performance of the shear calibration framework using simulated imaging data for the Nancy Grace Roman Space Telescope (Roman) reference High-Latitude Imaging Survey (HLIS). The weak lensing program of the Roman mission requires the mean weak lensing shear estimate to be calibrated within about 0.03%. To reach this goal, we can test our calibration process with various simulations and ultimately isolate the sources of residual shear biases in order to improve our methods. In this work, we build on the Roman HLIS image simulation pipeline in Troxel et al. (2021) to incorporate several new realistic processing-pipeline updates necessary to more accurately process the imaging data and calibrate the shear. We show the first results of this calibration for six deg 2 of the simulated reference HLIS using and compare these results to measurements on more simple, faster Roman-like image simulations. In both cases, we neglect the impact of blending of objects. We find that in the simplified simulations, can calibrate shapes to be within 𝑚 = (−0.01 ± 0.10)%. When applied to the current most-realistic version of the simulations, the precision is much lower, with estimates of 𝑚 = (−1.34 ± 0.67)% for joint multi-band single-epoch measurements and 𝑚 = (−1.13 ± 0.60)% for multi-band coadd measurements. These results are all consistent with zero within 1-2𝜎, indicating we are currently limited by our simulated survey volume. Further work on testing the shear calibration methodology is necessary at higher precision to reach the level of the Roman requirements, in particular in the presence of blending. Current results demonstrate, however, that the method can work on undersampled space-based Roman imaging data at levels comparable to the requirements of current weak lensing surveys.

The Impact of Quadratic Biases on Cosmic Shear

“…We note that whilst the the metacalibration method (see e.g. Huff & Mandelbaum 2017;Yamamoto et al 2022) currently does not correct for non-scalar multiplicative bias fields that is could be generalised to do so. Finally, we note that the 20 dimensional parameter fit is very large, and there is considerable flexibility in the model and degeneracy.…”

DESI and DECaLS (D&D): galaxy-galaxy lensing measurements with 1% survey and its forecast

“…). Many attempts have been made to examine this tension, in terms of different systematics (Yamamoto et al 2022;Wright et al 2020;Yao et al 2020Yao et al , 2017Kannawadi et al 2019;Pujol et al 2020;Mead et al 2021;Secco et al 2022;Amon et al 2022;Fong et al 2019), different statistics (Asgari et al 2021;Joachimi et al 2021;Harnois-Déraps et al 2021;Shan et al 2018;Sánchez et al 2021;Leauthaud et al 2022;Chang et al 2019), and possible new physics (Jedamzik et al 2021). We also refer to recent reviews for the readers' references (Perivolaropoulos & Skara 2021;.…”