In a galaxy far, far away
A recent world first by WA researchers provides a glimpse of what to expect when the Square Kilometre Array is operational.
A team of Western Australian scientists has mapped two galaxies in unprecedented detail using a radio telescope located in the state’s Murchison region.
The Large Magellanic Cloud and Small Magellanic Cloud are satellite galaxies of the Milky Way.
Visible to the naked eye, the galaxies have been observed throughout history, but this is the first time they have been mapped using very low frequencies of radiation.
The radio telescope allowed researchers from the International Centre for Radio Astronomy Research (Icrar) to find cosmic rays and hot gas, and identify areas where new stars were born, as well as remnants from stellar explosions.
It was set up in preparation for the Square Kilometre Array, and has been using the Murchison Widefield Array radio telescope to map the southern sky.
The MWA is a precursor to the SKA, built on the WA site of the future telescope.
As an international project that will eventually have telescopes in WA and South Africa, funding for the SKA is expected to be above $1 billion.
Icrar director of science Lister Staveley-Smith told Business News this was the first time the Magellanic Clouds had been imaged in such a high resolution.
“These Magellanic clouds are the nearest large neighbours to us, it’s a bit like an extra-galactic equivalent of the moon orbiting the earth,” he said.
The radio telescope is able to detect cosmic rays, which Professor Staveley-Smith said originated from the remnants of stars that exploded long ago.
These rays came from the general medium between stars rather than the stars themselves, he said.
Icrar astronomer Bi-Qing For told Business News the Murchison region, 300 kilometres inland from Geraldton, was an ideal location for measuring cosmic rays because it was remote and radio quiet.
“If we are studying radio astronomy, we are limited by interference,” Dr For said.
“If we build a telescope in the outback, we don’t have human beings building radio towers or antennae.
“We are getting very clean data, meaning there is no radio interference.”
Researchers at Icrar are using the radiation received by the MWA to make images of the Magellanic clouds, comparing these to other galaxies.
This output is part of a long-term plan to test the capabilities of the MWA telescope, and inform the development of the SKA.
Professor Staveley-Smith said Icrar’s primary role was to prepare the WA science world and wider community for the SKA.
“The square kilometre array is just finishing its pre-construction phase, critical design reviews will be finished up next year,” he said.
“I believe construction will hopefully start sometime in or shortly after 2020.
“In the meantime, we will continue to use the MWA, which will give us more fine detail on anything we look at.”
The cosmic mapping being produced by Icrar has also lead to other breakthroughs in the analysis of Magellanic clouds.
Icrar masters student Benjamin Armstrong said by looking at the rotation of stars, he had found some unusual differences within the Large Magellanic Cloud.
He believes the two Magellanic clouds may have had a third companion, suggesting another “luminous” galaxy was likely engulfed by the Large Magellanic Cloud some three to five billion years ago.
Mr Armstrong, who used computer simulation and images of the Magellanic clouds to mimic a galaxy merger, said the finding could help to explain a problem that has perplexed astronomers for years.
“In galaxies, there are these large objects called star clusters,” he said.
“Star clusters contain many, many, many stars that are all of quite similar ages and made in similar environments.
“In the Milky Way, the star clusters are all very old.
“But in the Large Magellanic Cloud, we have very old clusters as well as ones that are very young, but nothing in between.”