Gravitational lens effect on the cosmic background radiation due to nonlinear inhomogeneities

Null geodesic equations are numerically solved, in order to investigate the light propagation in inhomogeneous cosmological models. The models are derived using the N body simulation method and assuming for simplicity that clusters of galaxies are regarded as particles. Statistical properties of angular fluctuations of light paths and angular correlation fuctions of the cosmic background radiation are studied. It is shown that the angular fluctuation due to gravitational lensing depend much on the particle size. If it is equal to the size of the Coma cluster, the lens effect is so large to decrease the finite-beam-smeared temperature fluctuations of the cosmic backgound radiation by a factor ≥2, compared with those in the no-lens case, while the non-smeared temperature fluctuations are much enhanced for angles ≥0.5 arcmin. (author)