Galactic emissions: seeing through the Galaxy

The diffuse matter in our Galaxy is certainly to be damned by the cosmologist because it pollutes the CMB sky with the various emissions from its components: dust, ionised gas (free–free) and energetic particles (synchrotron). We detail here our knowledge, but also the unknowns, regarding these radiation sources. As we are not in a position to be able to physically escape our Galaxy, the better knowledge of these foreground components is our only hope to build a consistent model which will at least allow us a virtual escape. However, the detailed understanding of the physics of the different emissions and of the large scale distribution of the various emitters is a delight for many of us. We will show here some aspects, with a peculiar emphasis on a possible emission from tiny rotating grains. To cite this article: M. Giard, G. Lagache, C. R. Physique 4 (2003).