Importance of the GeV–TeV range

The GeV–TeV gamma-ray range holds a strategically important role in astrophysics, by providing the first high quality surveys of most classes of very high and ultra-high energy sources, including sufficiently large numbers of objects in each class to be able to start doing statistical classifications of their properties. The number of photons collected for individual sources in this energy range extends in some cases into the tens of thousands, leading in many cases to quite high signal-to-noise ratios.

The GeV–TeV photon emission provides not only important information about the photon emission mechanisms and the source physical properties, but also clues for the importance of the corresponding very high energy (TeV and up) neutrinos and even higher energy cosmic rays which may be emitted from such sources [44]. In addition to the discrete astrophysical sources, instruments in this energy range also provide information about the diffuse gamma-ray emission, such as that associated with cosmic rays interacting with the gas in the plane of our galaxy, the diffuse emission from our galactic center, and the extragalactic emission component, all of which could yield information or constraints about possible dark matter annihilation processes, in addition to the astrophysical processes and the sources involved.