Very high-energy (VHE) gamma-ray astrophysics is an exciting field spanning fundamental physics and extreme astrophysical processes. We detect the Cherenkov light emitted when VHE gamma rays from space hit the Earth’s atmosphere, using optical telescopes on the ground fitted with high-speed detectors similar to those used by the Large Hadron Collider, and also with water-filled Cherenkov detectors at high-altitude sites. Our science goals include:
- understanding the natures and variety of particle acceleration around black holes;
- understanding the origin of cosmic rays and their role in the Universe;
- searching for the ultimate nature of matter and physics beyond the Standard Model.
At Oxford we are involved in three major international experiments.
The High Energy Stereoscopic System (H.E.S.S.) consists of five telescopes in the Khomas Highlands of Namibia, one of the darkest sites for astronomy in the world. H.E.S.S. is at present the world’s largest gamma-ray observatory.
The international Cherenkov Telescope Array (CTA) is the next-generation ground-based observatory, which has just commenced construction. It will have two arrays, totalling one hundred telescopes. One array is in the Northern Hemisphere, on La Palma in the Canary Islands, and one in the Southern Hemisphere, at Cerro Paranal in Chile.
At the very highest photon energies, the proposed Southern Wide-Field Gamma-ray Observatory (SWGO) will have water Cherenkov detectors at an extremely-high-altitude site in the Andes.
Astronomers at Oxford have also been leading the radio-wavelength followup of GRBs detected by the ground-based gamma-ray observatories.