CTAO

Infrastructure and User Services

The CTAO will consist of two telescope arrays: one on the island of La Palma, Spain, in the northern hemisphere (CTAO-North) and one  in the Atacama Desert near Paranal, Chile, in the southern hemisphere (CTAO-South). CTAO-North will consist of 4 Large-Sized Telescopes (23m diameter) and 9 Medium-Sized Telescopes (12 m). CTAO-South will consist of 14 Medium-Sized Telescopes and 37 Small-Sized Telescopes (4.3 m). The telescopes are strategically arranged to maximize the chances of detecting gamma-ray-induced air showers with multiple instruments. Each telescope type is equipped with specialized detectors tailored to its design.

The CTAO ERIC (also known as Central Organisation) is in charge of managing the construction and operation of the Observatory. Besides its two telescope array sites, the CTAO ERIC has its headquarters in Bologna, Italy, and its Science Data Management Centre (SDMC) in Zeuthen, Germany. The staff at the headquarters provides project, science, technical and administration management, while the SDMC staff coordinates the processing and long-term preservation of data and provides support and data services for the Observatory. 

The CTAO ERIC works in close cooperation with partners from around the world toward the development of the Observatory: the CTAO In-Kind Contribution Collaborations develop essential hardware and software for the Observatory, like the telescope collaborations responsible for the construction of each type of telescope, and the CTAO Consortium, an international group of researchers, works on the scientific exploitation of the Observatory.

Examples/description of the type of research

The most energetic cosmic sources accelerate particles to extreme energies through a combination of rapid gas motions — sometimes near the speed of light — and strong magnetic fields. These conditions are found around stellar and black holes, where infalling matter generates intense magnetic fields and powerful jets, as well as in supernova explosions, gamma-ray bursts, star forming regions, and pulsars.

These energetic particles — or cosmic rays — are detected by satellites and ground-based instruments. However, since cosmic rays do not travel in straight lines due to magnetic deflections, their origins remain uncertain. To directly study the cosmic particle accelerators, astronomers turn to the gamma rays they emit. Gamma-ray observations help determine the maximum energy to which cosmic rays are accelerated, pinpoint their acceleration sites, and reveal the total energy contained in these particles.

Some cosmic-ray accelerators operate briefly, producing additional signals such as high-energy neutrinos, gravitational waves from merging black holes or neutron stars, and electromagnetic radiation across the spectrum. The CTAO will be a key facility for such “multi-wavelength” and “multi-messenger” astrophysics, linking gamma-ray observations with these events.

Finally, gamma rays could reveal the nature of dark matter. While only 15% of the Universe’s matter consists of known particles, the rest is likely composed of unknown forms, such as weakly interacting massive particles (WIMPs). If WIMPs annihilate, they may produce gamma rays, making their detection a key goal for the CTAO. Targeted observations of dense matter regions, such as the Galactic Center could help to identify the nature of dark matter.

How to access the infrastructure?

The CTAO is the first ground-based gamma-ray observatory to operate as an open, proposal-driven facility. Observations will be selected based on research proposals, which consists of a science justification and the number of observing hours needed for the science goals. The proposals are typically written by an international group of scientists. A selection committee will evaluate and select the research proposals. The observations will then be scheduled and carried out by on-site science operation teams in Chile (CTAO-South) and on La Palma (CTAO-North).