14 DAY TRIAL // Officials from 12 countries around the world met on Thursday, April 10, to discuss the final location for the Cherenkov Telescope Array (CTA), a planned observatory to study the night sky in gamma-ray wavelengths. During the previous meeting, five candidate sites were selected, and the new conference helped participants narrow them down even further. Just two candidate sites now remain for the CTA.
When the array is completed, it will consist of two sets of Imaging Atmospheric Cherenkov Telescopes (IACT), which are specialized instruments used for ground-based observation of gamma-rays. Existing installations, such as the High Energy Stereoscopic System (HESS) or the Very Energetic Radiation Imaging Telescope Array System (VERITAS), can image gamma-ray photons at energy levels between 50 gigaelectronvolts (GeV) and 40 teraelectronvolts (TeV).
CTA is scheduled to be one order of magnitude more sensitive to gamma-rays than HESS, VERITAS, or the Major Atmospheric Gamma-ray Imaging Cherenkov Telescopes (MAGIC). It will be sensitive to photons released between several tens of GeV to more than 100 TeV, which is more than twice what the other IACT can see today.
Following the meeting held last week in Munich, Germany, representatives from the 12 countries involved in building the CTA selected a site in Aar, southern Namibia, and one at Cerro Armazones, in Chile, as potential locations to assemble the array. A reserve site was selected in Argentina, in case the other two become unavailable for some reason.
Originally, the two final candidate sites were supposed to be designated by the end of 2013, but a series of delays pushed this term back by a few months. The CTA project is expected to cost the 12 countries involved around $276 million (€200 million). Sites in Mexico, Spain, and the United States were also considered, but the panel decided they required additional analysis.
The new gamma-ray array is being developed by the United Kingdom, Germany, France, Spain, Italy, Poland, Austria, Argentina, Brazil, South Africa, Switzerland, and Namibia. Representatives from these countries said at the meeting that the two sites they have selected would contain the Southern Hemisphere portion of CTA. One of the three sites still under study will house the northern component.
Between themselves, the two sites will share around 120 individual telescopes, all of which will be focused on identifying how the cascade of particles and blue light released as gamma-rays impact our planet's atmosphere. The goal of CTA will be to use multiple observation angles to determine the energy and path of these photons, thus identifying their source.
Gamma-rays are produced by extremely energetic objects and events in the Universe, such as supernova blasts, black holes, active galactic nuclei, quasars, and so on. Once online, CTA will study these phenomena, hoping to also clear up some of the mysteries surrounding quantum gravity and dark matter in the process, Nature News reports.