Probing Galactic Plasma with Radio Measurements

The detailed study of radio continuum emission allows a direct evaluation of the conditions of the Galactic plasma as well as of some important parameters describing the dynamics and structure of the Galaxy. An additional, independent motivation for accurate knowledge of the diffuse Galactic background is that such emission represents one of the main sources of unwanted signal in experiments dedicated to measure the Cosmic Microwave Background (CMB). The mechanism responsible for radio continuum from the Galactic plasma are synchrotron and thermal Bremsstrahlung emissions. In this work we present the results of our analysis on diffuse synchrotron emission: we revised the current status of data and removed systematic effects in present surveys with the aim to construct detailed maps of the spectral index and normalization factor over the whole observed sky with sub-degree angular resolution. The resulting distribution of the spectral index is representative for the Galactic diffuse synchrotron emission, with only minor effects from free-free and point sources. Moreover we present the most up-to-date compilation of HII regions comprising 1422 objects for which we study the level of completness as well as their spatial distribution. We further investigate their properties constructing a 3-D distribution of the sampled HII regions as a function of their distance from the Sun. This catalog could be extremely useful for present and future microwave CMB experiments.