出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Galactic synchrotron emission represents the most relevant foreground contamination in cosmic
microwave background (CMB) anisotropy observations at angular scales q >∼
1◦ and frequencies
n <∼
70 GHz. The accurate understanding of its polarization properties is crucial to extract
the cosmological information contained in the CMB polarization anisotropy. Radio surveys at
n ∼ 1 GHz offer the unique opportunity to study Galactic synchrotron emission where it represents
the dominant component, possibly except for regions close to the Galactic plane where
free-free emission is also important. We review the observational status of Galactic radio surveys
at scales q >∼
0.5◦. Leiden surveys, thanks to their frequency coverage from 0.408 GHz
to 1.411 GHz, still remain of fundamental importance for the comprehension of depolarization
phenomena. Recent surveys at 1.42 GHz (in both total intensity and polarization) with a better
sensitivity and sky sampling now cover both celestial hemispheres and allow to accurately map
the correlation properties of the diffuse synchrotron emission. We present an analysis of these
surveys in terms of angular power spectrum. A comparison of a simple frequency extrapolation
of these results with the recent WMAP results shows that we are close to map the bulk of the diffuse
synchrotron polarization fluctuations and to understand the corresponding implications for
CMB experiments.
