New constraints on Parity Symmetry from a re-analysis of the WMAP-7 low resolution power spectra

TL;DR

This paper tests the parity symmetry of the CMB using WMAP 7 data, confirming anomalies in temperature but finding no violations in polarization or cross-spectra, and forecasts Planck's future capabilities.

Contribution

It applies a quadratic maximum likelihood estimator to analyze parity symmetry in CMB polarization and temperature, confirming previous anomalies and extending analysis to polarization data.

Findings

Confirmed parity anomaly in TT for multipoles 2-22 at >99.5% CL

No anomalies detected in EE, TE, BB spectra

Cross-spectra TB and EB are consistent with zero

Abstract

The Parity symmetry of the Cosmic Microwave Background (CMB) pattern as seen by WMAP 7 is tested jointly in temperature and polarization at large angular scale. A Quadratic Maximum Likelihood (QML) estimator is applied to the WMAP 7 year low resolution maps to compute all polarized CMB angular power spectra. The analysis is supported by 10000 realistic Monte-Carlo realizations. We confirm the previously reported Parity anomaly for TT in the range $\delta \ell=[2,22]$ at $> 99.5%$ C.L.. No anomalies have been detected in TT for a wider $\ell$ range (up to $\ell_{max}=40$). No violations have been found for EE, TE and BB which we test here for the first time. The cross-spectra TB and EB are found to be consistent with zero. We also forecast {\sc Planck} capabilities in probing Parity violations on low resolution maps.