Time-variable diffuse gamma-ray foreground

Asteroids in the Solar System are permanently bombarded with cosmic rays which leads to an albedo effect from keV to GeV photon energies. Because of the relative motion of asteroid accumulations with respect to the moving Earth, their cumulative gamma-ray albedo shows a proper motion along the ecliptic, reminiscent of epicycles. Torus-like groups, such as the Main Belt Asteroids or the Kuiper Belt, will result in a wobbling and extended band of emission with a timescale of one sidereal year in Galactic coordinates. Jovian and Neptunian trojans can be identified as distinct features preceding and trailing the planets with motions according to their parent bodies’ periods. I will show that if these objects are not properly taken into account in gamma-ray data analyses, which typically relies on emission templates as a function of position and energy, artificial emission features can be created which are easily misinterpreted. With the two examples of the “OSSE 511 keV fountain” and the so-called “Galactic Centre Excess”, I will demonstrate that individual components can be explained or the model rejected without the need for extraordinary assumptions.