CMB map derived from the WMAP data through Harmonic Internal Linear Combination

Abstract

We are presenting an Internal Linear Combination (ILC) CMB map, in which the foreground is reduced through harmonic variance minimization. We have derived our method by converting a general form of pixel-space approach into spherical harmonic space, maintaining full correspondence. By working in spherical harmonic space, spatial variability of linear weights is incorporated in a self-contained manner and our linear weights are continuous functions of position over the entire sky. The full correspondence to pixel-space approach enables straightforward physical interpretation on our approach. In variance minimization of a linear combination map, the existence of a cross term between residual foregrounds and CMB makes the linear combination of minimum variance differ from that of minimum foreground. We have developed an iterative foreground reduction method, where perturbative correction is made for the cross term. Our CMB map derived from the WMAP data is in better agreement with the WMAP best-fit $\Lambda$CDM model than the WMAP team's Internal Linear Combination map. We find that our method's capacity to clean foreground is limited by the availability of enough spherical harmonic coefficients of good Signal-to-Noise Ratio (SNR).

The whole sky CMB map, which is derived from the WMAP 5 year data through our method, is available in HEALPix FITS format at http://www.nbi.dk/~jkim/hilc The paper with higher resolution images also available at http://www.nbi.dk/~jkim/hilc

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• Parity Asymmetry in the CMBR Temperature Power Spectrum
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• Bayesian component separation and CMB estimation for the 5-year WMAP temperature data
• Reconstruction of high-resolution SZ maps from heterogeneous datasets using needlets
• Testing gaussianity, homogeneity and isotropy with the cosmic microwave background
• CMB polarization map derived from the WMAP 5 year data through Harmonic Internal Linear Combination
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• Searching for non-Gaussianity in the WMAP data
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• An Improved Diffuse Foreground Subtraction by ILC method: CMB Map and Angular Power Spectrum using Planck and WMAP Observations
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• Angular-planar CMB power spectrum
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• Zonal Modes of Cosmic Microwave Background Temperature Maps
• Non-Gaussianity in the HILC foreground-reduced three-year WMAP CMB map
• Thermal Sunyaev-Zeldovich measurements and cosmic infrared background leakage mitigation combining upcoming ground-based telescopes
• A Foreground Model Independent Bayesian CMB Temperature and Polarization Signal Reconstruction and Cosmological Parameter Estimation over Large Angular Scales
• Large-angle non-Gaussianity in simulated high-resolution CMB maps