An angular power spectrum analysis of the DRAO 1.4 GHz polarization survey: implications for CMB observations

Aims. The aim of the present analysis is to improve the knowledge of the statistical properties of the Galactic diffuse synchrotron emission, which constrains sensitive CMB anisotropy measurements. Methods. We have analysed the new DRAO 1.4 GHz polarization survey together with the Stockert 1.4 GHz total intensity survey and derived the angular power spectra (APSs) of the total intensity, the polarized emission, and their cross-correlation for the entire surveys and for three low-intensity regions. Results. The APSs of the diffuse synchrotron emission are modelled by power laws. For the E and B modes, a slope of a similar to [-3.0, -2.5] for the multipole range similar to[30,300] is found. By the extrapolation of these results to 70 GHz, we can estimate the Galactic synchrotron contamination of CMB anisotropies, and we find results that are compatible with the ones coming from WMAP 3-yr data. In the low-intensity regions, the cosmological primordial B mode peak at l similar to 100 should be clearly observable for a tensor-to-scalar ratio T/S >= 0.5 and a synchrotron temperature spectral index beta similar to -3. Its detection is also possible for T/S >= 0.005 and beta similar to -3, in case a separation of the foreground from the CMB signal could be achieved with an accuracy of similar to 5-10%. For the TE mode, a mask excluding vertical bar b(gal)vertical bar <= 5 degrees (for beta similar to -3.0) or vertical bar b(gal)vertical bar <= 20 degrees (for beta similar to -2.8) from the surveys is sufficient to render the foreground contamination negligible, thus confirming the ability of WMAP to have a clear view of the temperature-polarization correlation peak and antipeak series.