Separation of the Galactic Synchrotron Foreground and the CMB Polarization Measurements

The polarization of the CMBR represents a powerful test for modern cosmology. It allows to break the degeneracy of fundamental cosmological parameters, and also to observe the contribution of gravitational waves background to the CMBR anisotropy. To observe the CMBR polarization several experiments are either in progress or planned and SPOrt is one of the most promising planned by ESA. At the same time the observation of the CMBR polarization is a difficult task and one of the reasons is the presence of polarized foreground emission. For instance, galactic polarized synchrotron emission (according to some estimates) can completely mimic the polarization of the CMBR. Nevertheless, one can use mathematical properties of the spherical harmonics of the distribution of radiation over the sky to separate different contributions. In this paper the mathematical properties of the polarized synchrotron foreground and the physical mechanism that produces it are discussed. The separation of synchrotron polarization from the polarization generated by density cosmological perturbations is discussed as well.