The Effect of Gravitational Scattering on the Anisotropy of the Cosmic Background Radiation

Abstract

The homogeneity of the cosmic microwave background radiation (CBR) is one of the most severe constraint for theories of the structure formation in the universe. We investigated the effect of the gravitational scattering (lensing) of galaxies, clusters of galaxies, and superclusters on the anisotropy of the CBR by numerical simulations. Although this effect was thought to be unimportant, we found that the gravitational scatterings by superclusters can significantly reduce the anisotropy of the CBR. We took into account the exponential growth of the distance between two rays due to multiple scatterings. The bending angle of each ray grows through the random walk process. On the other hand, difference between two rays grows exponentially while it is small. This exponential growth is caused by coherent scatterings that two rays suffer, and was neglected in the previous studies. The gravitational scattering by superclusters reduces the observed temperature anisotropy of the CBR at present time approximately by 40--60 $\%$ from that at the recombination time for angular scale up to a few degrees if the supercluster were formed at $z=$2--4.

compressed uuencoded postscript, 9 pages including 4 figures, APJL accepted

Cited by in corpus (9)

• Probing the Universe with Weak Lensing
• The Effect of Physical Assumptions on the Calculation of Microwave Background Anisotropies
• Higher-Order Gravitational Perturbations of the Cosmic Microwave Background
• Lensing and caustic effects on cosmological distances
• Gravitational Magnification of the Cosmic Microwave Background
• The fractal distribution of galaxies and the transition to homogeneity
• Effect of Void Network on CMB Anisotropy
• The Effect of Weak Gravitational Lensing on the Cosmic Microwave Background Anisotropy: Flat versus Open Universes
• The Effect of Lensing on the Large-Scale CMB Anisotropy