TY - JOUR

T1 - Comparison of the Planck 2018 CMB polarization maps in the BICEP2/Keck region

AU - Liu, Hao

AU - Creswell, James

AU - Naselsky, Pavel

PY - 2020/6/1

Y1 - 2020/6/1

N2 - We examine the statistical properties of polarization maps from Planck 2018 within the patch of sky observed by the BICEP2/Keck experiment using the one point distribution function (1PDF), skewness, and kurtosis statistics. Our analysis is performed for the Q and U Stokes parameters and for the corresponding E- and B-modes of the CMB signals. We extend our analysis by studying the correlations between CMB polarization maps and residual maps (the difference between the full signal and the CMB map) for the frequency range of 100-217 GHz with both the Q/U and E/B approaches. Although all the CMB maps reveal almost Gaussian statistical properties for Q/U and E/B domains, we have detected very significant anomalies for cross-correlations with residuals at 100 GHz at the level of 3.7 sigma for the Commander map and 5.2 sigma for NILC, for both the Q and U parameters. Using the NILC-Commander difference, which does not contain a cosmological signal, we find a sub-dominant non-Gaussian component in Q skewness and kurtosis at the level of 4.3 sigma and 10 sigma, respectively. For the B-mode we have found a very high level of cross-correlation (0.63-0.69) between the NILC/Commander maps and the 143 GHz total signal, which cannot be associated with the cosmological component. These strong deviations suggest that remnants of foregrounds, systematic effects, and component separation exist in the 2018 Planck CMB polarization maps in the BICEP2 sky area, which is far away from the Galactic plane. Our analysis also demonstrates the preferability of the Q/U domain over E/B for determination of the statistical properties of the derived CMB signals, due to non-locality of the transition Q/U -> E/B.

AB - We examine the statistical properties of polarization maps from Planck 2018 within the patch of sky observed by the BICEP2/Keck experiment using the one point distribution function (1PDF), skewness, and kurtosis statistics. Our analysis is performed for the Q and U Stokes parameters and for the corresponding E- and B-modes of the CMB signals. We extend our analysis by studying the correlations between CMB polarization maps and residual maps (the difference between the full signal and the CMB map) for the frequency range of 100-217 GHz with both the Q/U and E/B approaches. Although all the CMB maps reveal almost Gaussian statistical properties for Q/U and E/B domains, we have detected very significant anomalies for cross-correlations with residuals at 100 GHz at the level of 3.7 sigma for the Commander map and 5.2 sigma for NILC, for both the Q and U parameters. Using the NILC-Commander difference, which does not contain a cosmological signal, we find a sub-dominant non-Gaussian component in Q skewness and kurtosis at the level of 4.3 sigma and 10 sigma, respectively. For the B-mode we have found a very high level of cross-correlation (0.63-0.69) between the NILC/Commander maps and the 143 GHz total signal, which cannot be associated with the cosmological component. These strong deviations suggest that remnants of foregrounds, systematic effects, and component separation exist in the 2018 Planck CMB polarization maps in the BICEP2 sky area, which is far away from the Galactic plane. Our analysis also demonstrates the preferability of the Q/U domain over E/B for determination of the statistical properties of the derived CMB signals, due to non-locality of the transition Q/U -> E/B.

KW - CMBR experiments

KW - CMBR polarisation

U2 - 10.1088/1475-7516/2020/06/023

DO - 10.1088/1475-7516/2020/06/023

M3 - Journal article

VL - 2020

JO - Journal of Cosmology and Astroparticle Physics

JF - Journal of Cosmology and Astroparticle Physics

SN - 1475-7516

IS - 6

M1 - 023

ER -