We perform detailed calculations of cosmic microwave background (CMB) anisotropies in a CDM-dominated open universe with primordial adiabatic density perturbations for a variety of reionization histories. The CMB anisotropies depend primarily on the geometry of the universe, which in a matter-dominated universe is determined by Ω, and the optical depth to the surface of last scattering. In particular, the location of the primary Doppler peak depends primarily on Ω and is fairly insensitive to the other unknown parameters, such as Ωb, h, A, and the shape of the power spectrum. Therefore, if the primordial density perturbations are adiabatic, measurements of CMB anisotropies on small scales may be used to determine Ω.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
- Cosmic microwave background
- Cosmology: theory
- Intergalactic medium
- Large-scale structure of universe