Cosmic Background Anisotropies in CDM Cosmology

Abstract

Cosmic microwave background (CMB) anisotropies and density fluctuations are calculated for flat cold dark matter (CDM) models with a wide range of parameters, i.e., $\Omega_0, h$ and $\Omega_B$ for both standard recombination and various epochs of reionization. Tables of the power spectrum of CMB anisotropies in the form of $C_\ell$'s as a function of $\ell$ are presented. Although the Harrison-Zeldovich initial spectrum is assumed in these tables, we present simple approximations for obtaining the $C_\ell$'s corresponding to a tilted spectrum from those with a Harrison-Zeldovich spectrum. The $\sigma_8$ values are obtained for the matter density spectrum, with $\sigma(10^\circ)$, fixed $Q_{rms-PS}$ and COBE DMR 2 year normalizations. Simple modifications of the fitting formula of the density transfer function which are applicable for models with high baryon density are given. By using both numerical results and these fitting formulae, we calculate the relation between $\sigma_8$ and $Q_{rms-PS}$, and find good agreement. Velocity fields are also calculated.