in Chile the construction of the largest gamma ray observatory in the world

Technology and observation: the Cherenkov effect

The CTAO is designed to intercept very high energy gamma rays originating from the most violent events in the cosmos. Since these rays do not penetrate the Earth’s atmosphere, the observatory uses an indirect technique: the detection of Cherenkov radiation.

When a high-energy gamma photon interacts with the atmosphere, it generates a cascade of charged particles that travel at speeds faster than the speed of light in the atmospheric medium, producing a faint flash of blue light lasting a few billionths of a second. To capture these signals, the CTAO-South will employ over 50 telescopes equipped with ultra-fast cameras and enormous mirrors.

Size and scope of the project

The complete observatory will include over 60 telescopes divided between the CTAO-South (southern hemisphere) and CTAO-North (northern hemisphere) sites, covering a total collection area exceeding one million square meters. The Chilean site alone will operate in an energy range between 20 GeV and 300 TeV, analyzing radiation billions of times more energetic than visible light.

“We are happy to welcome this innovative facility into the ESO family.”, said ESO Director General Xavier Barcons. “The start of construction of the southern site in the Atacama Desert represents a milestone for both CTAO and ESO, but also for Chile, as this new facility will strengthen the country’s position as a global center for astronomy“.

Thanks to unprecedented precision, the CTAO will allow astrophysicists to investigate the deepest mysteries of the Universe, starting from the study of the acceleration processes of relativistic particles to understand their origin, through the close-up observation of extreme environments such as black holes, neutron stars and supernova remnants, up to pushing to the frontiers of physics with the search for dark matter and testing the limits of Einstein’s theory of relativity.

Second Stuart McMuldroch, Director General of CTAO, the project is turning a vision into reality: “Thanks to the commitment of our global partners and the support of ESO, we are starting construction of what will be the most advanced gamma-ray observatory on Earth“.

Timetable and international collaboration

The construction of the foundations is entrusted to a consortium of Chilean companies, paving the way for the installation of the first telescopes scheduled for the end of 2026. The first scientific data and inaugural observations of the gamma-ray sky from Chile are expected within a year of the start of work.

The project is the result of an international collaboration that sees ESO as founding partner and host of the southern site, in synergy with the Chilean government and the National Agency for Research and Development (ANID).