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 largescale 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 multipleplane 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 similar to 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.