SKA Weak Lensing III: Added Value of Multi-Wavelength Synergies for the Mitigation of Systematics

Understand

In this third paper of a series on radio weak lensing for cosmology with the Square Kilometre Array, we scrutinise synergies between cosmic shear measurements in the radio and optical/near-IR bands for mitigating systematic effects.

• We focus on three main classes of systematics: (i) experimental systematic errors in the observed shear; (ii) signal contamination by intrinsic alignments; and (iii) systematic effects due to an incorrect modelling of non-linear scales.
• First, we show that a comprehensive, multi-wavelength analysis provides a self-calibration method for experimental systematic effects, only implying <50% increment on the errors on cosmological parameters.
• We also illustrate how the cross-correlation between radio and optical/near-IR surveys alone is able to remove residual systematics with variance as large as 0.00001, i.e.