Planck Data Reconsidered

David Spergel, Raphael Flauger, Renee Hlozek

Published 2013-12-11, updated 2015-01-28Version 2

The tension between the best fit parameters derived by the Planck team and a number of other astronomical measurements suggests either systematics in the astronomical measurements, systematics in the Planck data, the need for new physics, or a combination thereof. We re-analyze the Planck data and find that the $217\,\text{GHz}\times 217\,\text{GHz}$ detector set spectrum used in the Planck analysis is responsible for some of this tension. We use a map-based foreground cleaning procedure, relying on a combination of 353 GHz and 545 GHz maps to reduce residual foregrounds in the intermediate frequency maps used for cosmological inference. For our baseline data analysis, which uses 47% of the sky and makes use of both 353 and 545 GHz data for foreground cleaning, we find the $\Lambda$CDM cosmological parameters $\Omega_c h^2 = 0.1170 \pm 0.0025$, $n_s = 0.9686 \pm 0.0069$, $H_0 = 68.0 \pm 1.1\,\mathrm{km} \mathrm{s}^{-1}\mathrm{Mpc}^{-1}$, $\Omega_b h^2 = 0.02197 \pm 0.00026$, $\ln 10^{10}A_s = 3.082 \pm 0.025$, and $\tau = 0.090 \pm 0.013 $. While in broad agreement with the results reported by the Planck team, these revised parameters imply a universe with a lower matter density of $\Omega_m=0.302\pm0.015$, and parameter values generally more consistent with pre-Planck CMB analyses and astronomical observations. We compare our cleaning procedure with the foreground modeling used by the Planck team and find good agreement. The difference in parameters between our analysis and that of the Planck team is mostly due to our use of cross-spectra from the publicly available survey maps instead of their use of the detector set cross-spectra which include pixels only observed in one of the surveys. We show evidence suggesting residual systematics in the detector set spectra used in the Planck likelihood code, which is substantially reduced for our spectra.