Science for Brazil (Reino Unido)

Latin focus for astrophysics

Publicado em 12 janeiro 2015

Latin American research into astro-particle physics and high energy cosmic rays is set to pass a crucial milestone in 2015, when the location is chosen for a huge new radio-astronomy observatory in the southern hemisphere. At the same time an existing facility in Argentina is receiving an important upgrade to boost its ability to measure cosmic rays.

Brazil is involved in both projects.

The Cherenkov Telescope Array (CTA) is a multinational, world-wide project to construct a ground-based instrument exploring the cosmos at the highest photon energies. Over 1000 scientists and engineers from 5 continents, 28 countries and over 170 research institutes participate in the CTA project.

The purpose of the CTA is to help scientists understand the origin of cosmic rays and their role in the Universe; to understand the nature and variety of particle acceleration around black holes; and to search for the ultimate nature of matter and physics beyond the Standard Model.​​

CTA will consist of over 100 Cherenkov telescopes of 23-m, 12-m and 4-m dish size located at one site in the southern hempsphere (3 three square Kms)  and a smaller site in the northern hemisphere. CTA began as a European project, but now has representation from 29 countries. It should be completed by 2020.

The CTA array will have sites in both the northern and southern hemisphere. Mexico, Spain and the USA are candidates for the northern site. For the southern site, Latin America is a strong contender, with short-listed sites in Chile at the ESO (European Southern Observatory) telescope complex, and at Leoncito in Argentina. The other contender is Aar in Namibia.

The CTA project is an initiative to build the next generation ground-based very high energy gamma-ray instrument. It will serve as an open observatory to a wide astrophysics community and will provide a deep insight into the non-thermal high-energy universe. A short video outlining the envisaged arrays is availablehere. Subscribers to the journal Astroparticle Physics can read an article on CTA by clicking here.

A decision is expected in early 2015 on the location of the southern CTA array, marking the conclusion to research by 12 CTA country delegates to find the best site following a meeting in Munich held in April 2014.

Already, Latin America has the world’s largest facility for observing cosmic rays, the Pierre Auger Observatory in Argentina’s Mendoza Province. This facility is being upgraded with support from Brazil and other funding agencies.

At the Pierre Auger Observatory cosmic rays above 10 to the power of 20 eV are observed. The upgrade program being implemented at the Auger Observatory is expected to help researchers identify the sources of ultrahigh energy cosmic rays called muons.

These ultra-energetic subatomic particles are present in air showers but measuring them calls for a new generation of electronic devices to upgrade the the observatory’s 1,600 existing detectors. Spread over an area of 3,000 km2 on a vast plain overlooked by the Andes, the detectors are polyethylene tanks filled with 12,000 litres of purified water and instrumented with photomultiplier tubes. When the particles in an air shower pass through the water in the tank, they emit light that can be measured by the photomultipliers.

The Auger Observatory upgrade will cost an estimated US$15 million and is being partly financed by the leading regional funding agency in Brazil, the São Paulo Research Foundation (FAPESP).

FAPESP is also a funding partner for the CTA project, supporting participation by universitires in São Paulo state including, Instituto de Física – Universidade de São Paulo, Instituto de Física de São Carlos, Universidade de São Paulo, Centro de Ciências Naturais e Humanas – Universidade Federal do ABC, Instituto de Astronomia, Geofísico, e Ciências Atmosféricas, and the Núcleo de Formação de Professores – Universidade Federal de São Carlos.

The initial idea is to build an array of seven telescopes, which will form an embryo of the observatory called the CTA Mini-Array, and build the rest around it at a later stage. Three of the first seven telescopes will be built by Brazil as part of a Thematic Project supported by FAPESP. Construction will take place in Italy.

You can read a complete article about CTA by Brazilian journalist Elton Alisson by clicking here.