The two-and three-point correlation functions of the polarized five-year WMAP sky maps

TL;DR

This paper analyzes the two- and three-point correlation functions of WMAP five-year sky maps, revealing consistency in temperature data but significant foreground contamination in polarization data, especially at higher frequencies.

Contribution

It provides a detailed comparison of observed polarization correlation functions with foreground templates, highlighting residual galactic contamination in WMAP polarization data.

Findings

Temperature correlation functions match expectations.

Polarization correlation functions show significant foreground residuals.

Foreground contamination is more closely linked to dust than synchrotron templates.

Abstract

We present the two- and three-point real space correlation functions of the five-year WMAP sky maps, and compare the observed functions to simulated LCDM concordance model ensembles. In agreement with previously published results, we find that the temperature correlation functions are consistent with expectations. However, the pure polarization correlation functions are acceptable only for the 33GHz band map; the 41, 61, and 94 GHz band correlation functions all exhibit significant large-scale excess structures. Further, these excess structures very closely match the correlation functions of the two (synchrotron and dust) foreground templates used to correct the WMAP data for galactic contamination, with a cross-correlation statistically significant at the 2sigma-3sigma confidence level. The correlation is slightly stronger with respect to the thermal dust template than with the synchrotron template.