A Large Sky Simulation of the Gravitational Lensing of the Cosmic Microwave Background

Large-scale structure deflects cosmic microwave background (CMB) photons. Since large angular scales in the large-scale structure contribute significantly to the gravitational lensing effect, a realistic simulation of CMB lensing requires a sufficiently large sky area. We describe simulations that include these effects and present both effective and multiple-plane ray-tracing versions of the algorithm, which employs spherical harmonic space and does not use the flat-sky approximation. We simulate lensed CMB maps with an angular resolution of ~0.9'. The angular power spectrum of the simulated sky agrees well with analytical predictions. Maps generated in this manner are a useful tool for the analysis and interpretation of upcoming CMB experiments such as Planck and ACT.