Microwave Background Constraints on Cosmological Parameters

Abstract

We use a high-accuracy computational code to investigate the precision with which cosmological parameters could be reconstructed by future cosmic microwave background experiments. We focus on the two planned satellite missions: MAP and Planck. We identify several parameter combinations that could be determined with a few percent accuracy with the two missions, as well as some degeneracies among the parameters that cannot be accurately resolved with the temperature data alone. These degeneracies can be broken by other astronomical measurements. Polarization measurements can significantly enhance the science return of both missions by allowing a more accurate determination of some cosmological parameters, by enabling the detection of gravity waves and by probing the ionization history of the universe. We also address the question of how Gaussian the likelihood function is around the maximum and whether gravitational lensing changes the constraints.