There are many sources of extreme gamma radiation in the Cosmos. However, astrophysicists do not fully understand the processes which can acccelerate particles to energies such that they can emit radiation 100 billion times more energetic than visible light. They could thereby learn more about the physics of compact objects such as black holes, for example.
In order to study these sources in detail, a new international scale observatory is being born : the « Cerenkov Telescope Array » (CTA), a network of on the order of one hundred telescopes on two sites (south and north). Its construction is planned for the period 2015 to 2020 ; first light, but with of course an incomplete installation, is foreseen for around 2016.
Start for the construction of a CTA prototype
Within this international organization, the coordination of the GATE (GAmma-ray Telescope Elements) project has been entrusted to the Observatoire de Paris, via its Laboratoire Univers et Théories - LUTh and Instrument Pole (in the Département Galaxies, Etoiles, Physique et Instrumentation - GEPI). Five laboratories of the Île-de-France are involved in the creation of prototypes for the CTA (telescope, cameras, trigger systems, mirrors).
Thus, on the Meudon site of the Observatoire de Paris, has begun the construction of a "demonstrator" telescope for the future large, very high energy gamma ray, observatory. Currently, the cabling and the shelter have been installed. The work will take several months, followed by a testing period in 2014.
This will be a challenge for the scientific teams of the LUTh and the instrument pole, who will have to create a small prototype (SST, which stands for Small Size Telescope) of a Cerenkov telescope.
The primary mirror will be 4 meters in diameter. It will use the so-called "Schwarzschild-Couder" optical arrangement, never before applied in astronomy, which should help optimize the scientific return obtained with the CTA at extreme energies.
When gamma rays penetrate the terrestrial atmosphere, they produce transient showers of particles. The Cerenkov telescopes observe the flashes of light produced by these particles during their flight, which enables the characteristics of the gamma ray sources to be determined. These sources include supernova remnants, pulsar winds, and active galactic nuclei.
This project is coordinated by the Observatoire de Paris (the LUTh and the instrument pole) with the support of the Région Île-de-France, of the CNRS (INSU and IN2P3) and of the CEA (IRFU).
Are participating in this project D. Dumas (project manager), P. Laporte, J.-L. Dournaux, J.-M. Huet, H. Sol (PI), A. Zech, G. Fasola, F. De Frondat, C. Boisson, C. Rulten, J.-P. Amans, F. Sayède together with other members of the LUTh, the GEPI and the DIL.