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We calculate the gamma-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids (MBAs), Jovian and Neptunian Trojan asteroids, and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the gamma-ray albedo for the Main Belt, Trojans, and Kuiper Belt strongly depends on the small-body size distribution of each system. Based on an analysis of the Energetic Gamma Ray Experiment Telescope (EGRET) data we infer that the diffuse emission from the MBAs, Trojans, and KBOs has an integrated flux of less than ~6x10^{-6} cm^{-2} s^{-1} (100-500 MeV), which corresponds to ~12 times the Lunar albedo, and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). If detected by GLAST, it can provide unique direct information about the number of small bodies in each system that is difficult to assess by any other method. Additionally, the KBO albedo flux can be used to probe the spectrum of CR nuclei at close-to-interstellar conditions. The orbits of MBAs, Trojans, and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. Therefore, the asteroid gamma-ray albedo has to be taken into account when analyzing weak gamma-ray sources close to the ecliptic, especially near the Galactic center and for signals at high Galactic latitudes, such as the extragalactic gamma-ray emission. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the Galactic 511 keV line emission including the direction of the Galactic center.
The aim of the chapter is to summarize our understanding of the compositional distribution across the different reservoirs of small bodies (main belt asteroids, giant planet trojans, irregular satellites of the giant planets, TNOs, comets). We then u
Secondary nuclear production physics is receiving increased attention given the high-quality measurements of the gamma-ray emissivity of local interstellar gas between ~50 MeV and ~40 GeV, obtained with the Large Area Telescope on board the Fermi spa
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Notwithstanding the advent of the Gamma-ray Large Area Telescope, theoretical models predict that a significant fraction of the cosmic gamma-ray background (CGB), at the level of 20% of the currently measured value, will remain unresolved. The angula
The solar disk is a bright source of multi-GeV gamma rays, due to the interactions of hadronic cosmic rays with the solar atmosphere. However, the underlying production mechanism is not understood, except that its efficiency must be greatly enhanced