The physics of CMBR anisotropies

Abstract

The observed structures in the universe are thought to have arisen from gravitational instability acting on small fluctuations generated in the early universe. These spatial fluctuations are imprinted on the cosmic microwave background radiation (CMBR) as angular anisotropies. The physics which connects initial fluctuations in the early universe to the observed anisotropies is fairly well understood, since for most part it involves linear perturbation theory. This makes CMBR anisotropies one of the cleanest probes of the initial fluctuations, various cosmological parameters governing their evolution and also the geometry of the universe. We review here in a fairly pedagogical manner the physics of the CMBR anisotropies and explain the role they play in probing cosmological parameters, especially in the light of the latest observations from the WMAP satellite.