Cangaroo telescope leaps to cosmic ray proof

A team of Japanese and Australian astronomers has found concrete evidence of an elusive component in cosmic rays.

Cosmic rays are high energy particles that come from interstellar space and provide the radiation that enables evolution on earth. They are made up of enormously energetic protons, electrons and other charged particles that are believed to be accelerated by the blast wave of an exploding star.

While astronomers have long had evidence that the electron component of cosmic rays is created in this way, the evidence for proton acceleration has been harder to come by because they do not emit any detectable radiation.

However recent observations by the team with the Cangaroo gamma-ray telescope at Woomera, a collaboration between ANU and the Universities of Tokyo, Adelaide and Sydney, have provided evidence for high-energy protons in the blast wave associated with supernova RXJ 1713.

Dr Geoff Bicknell from the Research School of Astronomy and Astrophysics at ANU said protons near the blast wave caused gamma-rays to be produced which, when they reached earth, could be detected by Cangaroo.

"We are confident that these gamma-rays are the result of protons in the blast wave because no other model explains their presence adequately," he said.

Following additional funding by the Australian Research Council, three more telescopes will be constructed at Woomera, and Dr Bicknell said the increased sensitivity would enhance the ability to detect gamma-rays from many other astrophysical sources.

"These findings and equipment will greatly contribute to the study of plasma jets emitted by black holes, pulsars, supernova blast waves and other astronomical events," he said.

Item provided courtesy of ANU