"4n multipole periodicity" of the Galaxy image in the WMAP data

Abstract

We present a specific periodicity of the Galaxy images in the multipole domain which can be used for separation of the cosmic microwave background (CMB) signal from the Galaxy and foreground component. This method takes into consideration all the coefficients of the expansion of the signal from the sky ΔT(Θ, ϕ) into spherical harmonics and dealing with combination of multipoles a_{l,m} and a_{l+Δ,m} for each multipole mode (\ell, -\ell \le m \le \ell) from the whole sky without galactic cut, masks or any dissection of the whole sky into disjoint regions. For the polar coordinate system we use particular values for Δ=4n, n=1,2,... which remove all bright point-like sources localized in the Galactic plane and strong diffused component down to the CMB level. To illustrate that significant correlations of the point like sources and foregrounds a_{l,m},a_{l+Δ,m} coefficients we apply this method to the WMAP Q,V and W bands in order to remove these marks of Galaxy from the maps. We believe that our method would be useful for separation of the CMB signal from different kind of "noises" in the maps.