Galactic foregrounds: Spatial fluctuations and a procedure of removal
  Present day cosmic microwave background (CMB) studies require more accurate
removal of Galactic foreground emission. In this paper, we consider a way of
filtering out the diffuse Galactic fluctuations on the basis of their
statistical properties, namely, the power-law spectra of fluctuations. We focus
on the statistical properties of two major Galactic foregrounds that arise from
magnetized turbulence, namely, diffuse synchrotron emission and thermal
emission from dust and describe how their power laws change with the Galactic
latitude. We attribute this change to the change of the geometry of the
emission region and claim that the universality of the turbulence spectrum
provides a new way of removing Galactic foregrounds. We discuss and demonstrate
how we can make use of our findings to remove Galactic foregrounds using a
template of spatial fluctuations. In particular, we consider examples of
spatial filtering of a foreground at small scales, when the separation into CMB
signal and foregrounds is done at larger scales. We demonstrate that the new
technique of spatial filtering of foregrounds may be promising for recovering
the CMB signal in a situation when foregrounds are known at a scale different
from the one under study. It can also improve filtering by combining
measurements obtained at different scales.
