The origin of the belt of galactic radio waves

Extract

Most of the background of cosmic radio waves comes from our own Galaxy. In the equatorial plane this origin is evident, and the obvious features can be directly related to the Galaxy's structure. Away from the plane the emission comes from a roughly spherical halo, which accounts for most of the total emission from the Galaxy. Some features in this part of the sky are not evident from optical studies; the most important is a circular belt of emission passing not far from the center and the anti-center. It is impossible that this should be extragalactic in origin, since it is more than twice as bright as the brightest estimates of the whole galactic component, and optical evidence would be expected of such a major irregularity in the distribution of the galaxies, or indeed of a single spiral galaxy close to or enveloping our own. We turn therefore to a suggestion of an origin in our own Galaxy.