Forecast of Joint Analysis of Cosmic Shear and Supernovae Magnification from the CSST and LSST

Abstract

Cosmic shear and cosmic magnification reflect the same gravitational lensing field. Each of these two probes are affected by different systematics. We study the auto- and cross-correlations of cosmic shear from the China Space Survey Telescope and cosmic magnification of supernovae from the Large Synoptic Survey Telescope. We want to determine to what extent, by adding the magnification data, we can remove the systematic bias in cosmic shear measurements. We generate mock shear/magnification maps based on the correlation between different tomographic bins. After obtaining the corrected power spectra, we adopt the Markov Chain Monte Carlo technique to fit the theoretical models and investigate the constraints on the cosmological and nuisance parameters. We find that, with only the cosmic shear data, there are 1σ biases in the σ 8 and intrinsic alignment model parameters. By adding the magnification data, we are able to remove these biases perfectly.