Foregrounds and Forecasts for the Cosmic Microwave Background
M.Tegmark, D.J.Eisenstein, W.Hu, A. de Oliveira-Costa
Abstract
One of the main challenges facing upcoming CMB experiments will be to distinguish the cosmological signal from
foreground contamination. We present a comprehensive treatment of this problem and study how foregrounds
degrade the accuracy with which the Boomerang, MAP and Planck experiments can measure cosmological
parameters. Our foreground model includes not only the normalization, frequency dependence and scale dependence
for each physical component, but also variations in frequency dependence across the sky. When estimating how
accurately cosmological parameter can be measured, we include the important complication that foreground model
parameters (we use about 500) must be simultaneously measured from the data as well. Our results are quite
encouraging: despite all these complications, precision measurements of most cosmological parameters are degraded
by less than a factor of 2 for our main foreground model and by less than a factor of 5 in our most pessimistic scenario.
Parameters measured though large-angle polarization signals suffer more degradation: up to 5 in the main model
and 25 in the pessimistic case. The foregrounds that are potentially most damaging and therefore most in need of
further study are vibrating dust emission and point sources, especially those in the radio frequencies. The
cross-correlation between polarized and unpolarized foregrounds also deserves further study, as we find that it
carries much more information than E-polarization about most cosmological parameters. (553kb)
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Publication Info
Astrophys. J. (submitted)
whu@ias.edu
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