2007/10/23 by Michael J. Mortonson, Wayne Hu · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Cosmology and Gravitation Theories #Geophysics and Gravity Measurements #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.1103/physrevd.77.043506
published as Phys.Rev.D77:043506,2008 · 9 pages, 6 figures; submitted to Phys. Rev. D
arxiv created 2007/10/23 · openalex publication_date 2008/02/07 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Estimates of inflationary parameters from the CMB B-mode polarization spectrum on the largest scales depend on knowledge of the reionization history, especially at low tensor-to-scalar ratio. Assuming an incorrect reionization history in the analysis of such polarization data can strongly bias the inflationary parameters. One consequence is that the single-field slow-roll consistency relation between the tensor-to-scalar ratio and tensor tilt might be excluded with high significance even if this relation holds in reality. We explain the origin of the bias and present case studies with various tensor amplitudes and noise characteristics. A more model-independent approach can account for uncertainties about reionization, and we show that parametrizing the reionization history by a set of its principal components with respect to E-mode polarization removes the bias in inflationary parameter measurement with little degradation in precision.