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 (CMB) experiments, in particular the two satellite missions MAP and Planck Surveyor (COBRAS/SAMBA). We identify several parameter combinations that could be determined with a few percent accuracy with MAP and the Planck Surveyor, 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 measurments can significantly enhance the science return of both missions by allowing accurate determination of 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.