Cosmology with the CMB temperature-polarization correlation

TL;DR

This paper shows that the CMB temperature-polarization cross-correlation (TE) provides accurate, robust constraints on cosmological parameters, often outperforming temperature data alone due to lower contamination from astrophysical foregrounds.

Contribution

It demonstrates the effectiveness of TE spectrum analysis using Planck data for constraining cosmological parameters, especially in the context of foreground contamination and systematics.

Findings

TE spectrum yields competitive constraints for ΛCDM parameters.

TE is less affected by foregrounds than the temperature spectrum.

Instrumental noise limits the precision for extended ΛCDM models.

Abstract

We demonstrate that the cosmic microwave background (CMB) temperature-polarization cross-correlation provides accurate and robust constraints on cosmological parameters. We compare them with the results from temperature or polarization and investigate the impact of foregrounds, cosmic variance, and instrumental noise. This analysis makes use of the Planck high-multipole HiLLiPOP likelihood based on angular power spectra, which takes into account systematics from the instrument and foreground residuals directly modelled using Planck measurements. The temperature-polarization correlation (TE) spectrum is less contaminated by astrophysical emissions than the temperature power spectrum (TT), allowing constraints that are less sensitive to foreground uncertainties to be derived. For {\Lambda}CDM parameters, TE gives very competitive results compared to TT. For basic {\Lambda}CDM model extensions (such as AL, {\Sigma}m{\nu}, or Neff ), it is still limited by the instrumental noise level in the polarization maps.