Non-Gaussianity in CMB lensing from full-sky simulations

The lensing convergence field describing the weak lensing effect of the Cosmic Microwave Background (CMB) radiation is expected to be subject to mild deviations from Gaussianity. We perform a suite of full-sky lensing simulations using ray tracing through multiple lens planes — generated by combining N-body simulations on smaller scales and low-to-intermediate redshifts with realisations of Gaussian random fields on large scales and at high redshifts. We quantify the non-Gaussianity of the resulting convergence fields in terms of a set of skewness and kurtosis parameters and show that the non-Gaussian information in these maps can be used to constrain cosmological parameters such as the matter density Ω m h 2 or the amplitude of primordial curvature perturbations A s . We forecast that for future CMB lensing observations, combining the non-Gaussian parameters with the Gaussian information can increase constraining power on (Ω m h 2 , A s ) by a few per cent compared to constraints from Gaussian observables alone. We make the simulation code for the full-sky lensing simulation available for download from GitHub ( https://github.com/Kang-Yuqi/FLAReS ).