Fermi-LAT: First Year Observations Of The Solar System In Gamma Rays
Abstract
We present an analysis of the first 12 months of data collected by the Large Area Telescope (LAT) on board of the Fermi observatory. The LAT has observed the high-energy gamma-ray emission from the Earth with unprecedented detail and measured the spectrum and angular distribution of the emission from the quiet Sun and the Moon. This emission is produced by interactions of Galactic cosmic-ray nucleons with the solar and Earth's atmospheres and with the solid surface of the Moon. Additionally, inverse-Compton scattering of Galactic cosmic-ray electrons off solar photons in the heliosphere produces extended emission covering the entire sky with a maximum of the emission coming at small elongation angles. The fluxes of these solar-system objects are expected to vary over the solar cycle due to the heliospheric modulation of cosmic rays. The high level of the observed flux reflects the extended minimum in solar activity and decreased heliospheric modulation. The observed fluxes are compared with model calculations.
- Publication:
-
AAS/High Energy Astrophysics Division #11
- Pub Date:
- March 2010
- Bibcode:
- 2010HEAD...11.1002M