Principal component analysis of the reionization history from Planck 2015 data

Abstract

The simple assumption of an instantaneous reionization of the Universe may bias estimates of cosmological parameters. In this paper a model-independent principal component method for the reionization history is applied to give constraints on the cosmological parameters from recent Planck 2015 data. We find that the Universe are not completely reionized at redshifts $z\ge 8.5$ at 95% CL. Both the reionization optical depth and the matter fluctuation amplitude are higher than but consistent with those obtained in the standard instantaneous reionization scheme. The high estimated value of the matter fluctuation amplitude strengthens the tension between Planck CMB observations and some astrophysical data, such as cluster counts and weak lensing. The tension can significantly be relieved if the neutrino masses are allowed to vary. Thanks to a high scalar spectral index, the low-scale spontaneously broken SUSY inflationary model can fit the data well, which is marginally disfavored at 95% CL in the Planck analysis.

7 pages, 7 figures

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Cited by in corpus (6)

• Eliminating the optical depth nuisance from the CMB with 21 cm cosmology
• Complete Reionization Constraints from Planck 2015 Polarization
• RELIKE: Reionization Effective Likelihood from Planck 2018 Data
• Constraining the reionization history with CMB and spectroscopic observations
• Effect of the Early Reionization on the Cosmic Microwave Background and Cosmological Parameter Estimates
• Cosmic Reionization Study : Principle Component Analysis After Planck