Results from Imaging Atmospheric Cherenkov Telescopes in the USA

Abstract:

The night sky is filled with flashes of blue Cherenkov light, which last for just a few billionths of a second. Invisible to our eyes, these flashes result from particle cascades in the Earth's atmosphere, triggered by the arrival of a high energy cosmic ray or gamma ray from space. They can be recorded using large reflecting Cherenkov telescopes equipped with very fast photosensor cameras. Studying the gamma-ray signals allows us to understand the particle acceleration processes occurring in some of the most extreme environments in the Universe - close to black holes, neutron stars, supernova remnants and relativistic jets. These gamma-ray Cherenkov telescopes are also the largest optical telescopes in the world, and can be used to study rapid optical phenomena such as stellar intensity correlations and asteroid occultations.

The field was pioneered at the Whipple Observatory in Arizona, and remains a very active area of astrophysical research in the USA. I will summarize its development, some important results, and the current status.