Irish scientists have contributed to an important astronomical discovery published yesterday (Thursday, 10 December) in the prestigious academic magazine Nature. Scientists from NUI Galway, Galway-Mayo Institute of Technology, CIT and UCD are part of the VERITAS project which has found evidence to support the theory that cosmic rays are powered by exploding stars and stellar winds. This discovery has been predicted for almost 20 years, but until now no instrument was sensitive enough to see it. VERITAS is operated by a collaboration of more than 100 scientists from 22 different institutions in the US, Ireland, England and Canada. Using an array of four giant telescopes based at the Smithsonian Astrophysical Observatory in Arizona, the VERITAS project observed very high energy gamma radiation from the 'starburst' galaxy M82, often called the 'Cigar Galaxy'. Through deep observations of M82 the scientists made significant discoveries about cosmic rays. Scientists first detected signs of cosmic rays, which are subatomic particles that zip through space at nearly the speed of light, some 100 years ago. The challenge for astronomers, which the VERITAS project has finally succeeded in, has been to answer the question as to which natural force could accelerate particles to such high energies. Dr Gary Gillanders from the Centre of Astronomy at NUI Galway is one of the Irish scientists involved in VERITAS and a member of the VERITAS Science Board: "This discovery provides fundamental insight into the origin of cosmic rays and is an important scientific milestone in astronomy. The VERITAS observations strongly support the long-held belief that supernovae and stellar winds from massive stars are the dominant accelerators of cosmic ray particles". VERITAS could not detect M82 s cosmic rays directly but looked for clues to their presence. When cosmic rays interact with interstellar gas and radiation, they produce gamma rays, which were then detected by the VERITAS team and used to infer that cosmic rays were indeed present and being accelerated to high energies. The scientific revelation in Nature magazine is the culmination of two years of dedicated data collection and analysis by the VERITAS team. Dr Pat Moriarty, a VERITAS scientist from Galway-Mayo Institute of Technology remarked: "This project is an example of scientists at four Irish third-level Institutions collaborating in a world-class experiment". The other Irish co-investigators in VERITAS are Dr Mark Lang at NUI Galway, Dr Paul Reynolds at CIT and Dr John Quinn at UCD. The Irish VERITAS members are part funded by Science Foundation Ireland. -Ends-