The One-dimensional Fourier Representation and Large Angular Scale Foreground Contamination in the 3-year Wilkinson Microwave Anisotropy Probe data

Abstract

We employ the one-dimensional Fourier representation (1DFR) to analyze the 3-year WMAP de-biased internal linear combination (DILC) map and its possible contamination by galactic foregrounds. The 1DFR is a representation of the spherical harmonic coefficients for each l mode using an inverse Fourier transform into one-dimensional curves. Based on the a priori assumption that the CMB signal should be statistically independent of, and consequently have no significant correlation with, any foregrounds, we cross-correlate the 1DFR curves of 2 <= l <= 10 modes, which are claimed by the WMAP team to be free of contamination and suitable for whole sky analysis. We find that 8 out of the 9 modes are negatively cross correlated with the foreground maps, an event which has a probability of only 9/512 ~ 0.0176 for uncorrelated signals. Furthermore, the local extrema of the 1DFR curves between the DILC and those of the foregrounds for l=2 and 6 are correlated with significance level below 0.04. We also discuss the minimum variance optimization method and use the properties of the measured cross-correlation to estimate the possible level of contamination present in the DILC map.

Accepted for publication to JCAP after adding a further correlation test with the foreground templates that are independent from WMAP data : 408 MHz radio continuum map, H-alpha map and the dust map extrapolated from COBE/DIRBE data, which show significant correlation with the DILC map

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• Statistical Characterization of Temperature Patterns in Anisotropic Cosmologies
• Searching for planar signatures in WMAP
• The impact of dipole straylight contamination on the alignment of low multipoles of CMB anisotropies
• Foreground removal from CMB temperature maps using an MLP neural network
• Phase analysis of the cosmic microwave background from an incomplete sky coverage
• Temperature and Polarization Patterns in Anisotropic Cosmologies
• Zonal Modes of Cosmic Microwave Background Temperature Maps