How to foot cosmic microwave background parameter estimation - art. no. 043001

With the release of the data from the Boomerang and MAXIMA-1 balloon Rights , estimates of cosmological parameters based on the cosmic microwave backgr ound (CMB) have reached unprecedented precision. In this paper I show that it is possible for these estimates to be substantially biased by features i n the primordial density power spectrum. I construct primordial power spect ra which mimic to within cosmic variance errors the effect of changing para meters such as the baryon density and neutrino mass, meaning that even an i deal measurement would be unable to resolve the degeneracy. Complementary m easurements are necessary to resolve this ambiguity in parameter estimation efforts based on CMB temperature fluctuations alone.