Assessing Consistency between WMAP 9 Year and Planck 2015 Temperature Power Spectra

Abstract

Abstract We perform a comparison of 9 year ( 9) and 2015 cosmic microwave background temperature power spectra across multipoles 30 ≤ ℓ ≤ 1200. We generate simulations to estimate the correlation between the two data sets due to cosmic variance from observing the same sky. We find that their spectra are consistent within 1σ. While we do not implement the optimal “C −1” estimator on maps as in the 9 analysis, we demonstrate that the change of pixel weighting only shifts our results at most at the 0.66σ level. We also show that changing the fiducial power spectrum for simulations only impacts the comparison at around 0.1σ level. We exclude ℓ < 30 both because 9 data were included in the 2015 ℓ < 30 analysis and because the cosmic variance uncertainty on these scales is large enough that any remaining systematic difference between the experiments is extremely unlikely to affect cosmological constraints. The consistency shown in our analysis provides high confidence in both the 9 temperature power spectrum and the overlapping multipole region of 2015's, virtually independent of any assumed cosmological model. Our results indicate that cosmological model differences between and do not arise from measurement differences, but from the high multipoles not measured by .