Lack of angular correlation and odd-parity preference in CMB data

Abstract

We have investigated the angular correlation in the recent CMB data. In addition to the known large-angle correlation anomaly, we find the lack of correlation at small angles with high statistical significance. We have investigated various non-cosmological contamination and additionally WMAP team's simulated data. However, we have not found a definite cause. In the angular power spectrum of WMAP data, there exist anomalous odd-parity preference at low multipoles. Noting the equivalence between the power spectrum and the correlation, we have investigated the association between the lack of large-angle correlation and the odd-parity preference. From our investigation, we find that the odd-parity preference at low multipoles is, in fact, a phenomenological origin of the lack of large-angle correlation. Futher investigation is required to find out whether the origin of the anomaly is cosmological or due to unaccounted systematics. The data from Planck surveyor, which has systematics distinct from the WMAP, will greatly help us to resolve its origin.