The Quiet Sun: Synchrotron Emission from Galactic Cosmic Rays as a New Component

The emission from the Sun in its quiet phase has been observed to extend from radio to gamma rays. Here we report our estimates of a new component: the synchrotron emission produced by Galactic cosmic rays on the magnetic field of the Sun and of the heliosphere. To the best of our knowledge, this is the first time that such an emission component has been considered when exploring the quiet Sun. In particular, we compare our models with the current upper limits to the quiet Sun observed by RHESSI in the 3–200 KeV band. We also show the expected spatial distribution of this emission, which we found to be maximum in the close vicinity of the Sun. This new emission component provides a more complete description of the quiet Sun and opens a new window for understanding not only cosmic rays in the Heliosphere and close to the Sun, but also the Sun itself, its environment, and the solar magnetic field.