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

TL;DR

This paper presents large-scale, high-resolution simulations of gravitational lensing of the CMB, incorporating realistic large-scale structure effects using spherical harmonic-based ray-tracing methods.

Contribution

It introduces a novel simulation approach that accurately models CMB lensing over large sky areas without flat sky approximation, suitable for upcoming experiments.

Findings

Simulated CMB maps match analytical power spectrum predictions.

The method effectively captures large-scale structure lensing effects.

Simulations are useful for interpreting data from experiments like PLANCK and ACT.

Abstract

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 arcmin. 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.