Planckintermediate results

Abstract

This paper describes the identification, modelling, and removal of previously unexplained systematic effects in the polarization data of the Planck High Frequency Instrument (HFI) on large angular scales, including new mapmaking and calibration procedures, new and more complete endto-end simulations, and a set of robust internal consistency checks on the resulting maps. These maps, at 100, 143, 217, and 353 GHz, are early versions of those that will be released in final form later in 2016. The improvements allow us to determine the cosmic reionization optical depth τ using, for the first time, the low-multipole EE data from HFI, reducing significantly the central value and uncertainty, and hence the upper limit. Two different likelihood procedures are used to constrain τ from two estimators of the CMB E-and B-mode angular power spectra at 100 and 143 GHz, after debiasing the spectra from a small remaining systematic contamination. These all give fully consistent results. A further consistency test is performed using cross-correlations derived from the Low Frequency Instrument maps of the Planck 2015 data release and the new HFI data. For this purpose, end-to-end analyses of systematic effects from the two instruments are used to demonstrate the near independence of their dominant systematic error residuals. The tightest result comes from the HFI-based τ posterior distribution using the maximum likelihood power spectrum estimator from EE data only, giving a value 0.055 ± 0.009. In a companion paper these results are discussed in the context of the best-fit Planck ΛCDM cosmological model and recent models of reionization.

Status of Neutrino Properties and Future Prospects—Cosmological and Astrophysical Constraints

“…After reionization, the CMB photons are scattered again by the free electrons. Given the current estimates of cosmological parameters, z re ≃ 8 [43].…”

“…As a result, forecasts for S4 relies on external measurements of τ . The sensitivity σ ( m ν ) of S 4 TT,TE,EE,PP complemented with a Gaussian prior on the optical depth of τ = 0.06 ± 0.01 (roughly corresponding to the latest estimate from Planck-HFI [43]) is in the range [0.073 − 0.110] eV, depending on the angular resolution and noise level, for f sky = 40% [30]. 11 https://cmb-s4.org…”

“…In 2016, new estimates of the reionization optical depth τ have been published by the Planck collaboration [43], obtained from the analysis of the high-frequency CMB maps, in 2015 still affected by unexplained systematics effects at large scales. The estimated 68% credible interval for τ coming from the EE−only low-ℓ data is τ = 0.055 ± 0.009.…”

“…A lower τ implies a lower A S and thus a lower lensing amplitude, leaving less room for large values of m ν (that would further reduce lensing). If the "lowP" dataset is replaced by the new estimate of τ (labeled as "SimLow"), the 95% CL bounds improve as follows: m ν < 0.59 eV for Planck TT+SimLow and m ν < 0.34 eV for Planck TT,TE,EE+SimLow [43].…”

“…These constraints are also summarized in Table 2 for the reader's convenience. Planck CMB+LSST-shear c 30 [36] Planck+Euclid-FS 40 [133] Stage-III CMB (ACTPol)+WFIRST BAO+FS 30 [38] Stage-III CMB+WFIRST+Euclid+LSST 8 [38] a The combination assumes a Gaussian prior on τ = 0.06 ± 0.01 roughly corresponding to the new estimate from Aghanim et al [43]. b The combination assumes σ (τ ) = 0.002 and noise level of 2.5µK · arcmin.…”