Scientists from South Africa are playing a leading role in developing the science which will be done with the world’s largest telescope, the Square Kilometre Array.
The SKA telescope, to be built in Australia and South Africa, will allow scientists to look far back into the history of the universe and will give much more detail than before on how the universe has evolved over 14 thousand million years. More information will be obtained on how stars, galaxies and clusters of galaxies formed and how they have changed since the Universe was young. This will allow for the plotting of a 3D map of the Universe.
The international SKA Organisation, which includes eleven countries, is bringing up to date the science case for the telescope. South African scientists are playing a leading role in many of the working groups. The SKA Cosmology Working Group is chaired by Roy Maartens, SKA Research Professor at the University of the Western Cape (UWC). Professor Maartens and Professor Mario Santos, also a Research Professor at UWC, with astronomers from South Africa and the other SKA member countries, have played a leading role in setting out the SKA science.
Roy Maartens says: “Researchers here have devised a means of using the world’s largest telescope in new ways that will help shape the future of cosmology.”
Mario Santos says: “Usually a map of the Universe is made using galaxies as tiny beacons of the large scale structure of the Universe. This is quite demanding as it requires the mapping of large numbers of galaxies across the sky.”
“The survey we are proposing will measure the emitted radiation from all the hydrogen atoms spread across the Universe without actually detecting galaxies. This will make it easier to survey all of the sky across cosmic times, allowing the phase 1 of the SKA to become an extremely competitive cosmology machine,” he adds.
“By making these huge, 3D maps of the Universe we will be able to test the limits of General Relativity and maybe find some signature of new physics on these large scales which can shed light on the true nature of dark energy. Moreover, we can also look for imprints of what happened at the very beginning of the Universe,” added Santos.
An experiment like this, says Santos, using intensity mapping, has never been done before. The largest 3D maps of the large scale structure of the Universe have been done using optical telescopes. The current project will be about 50 times larger. Other future experiments, such as the Euclid satellite, will be able to also probe a large fraction of the Universe, but none will match the SKA in terms of size and depth.
Maartens adds: “It will be like making a movie of the Universe from a young age, when it was only about 2 billion years old, until today when it is about 14 billion years old. The movie will be low resolution but enough to test the fundamentals of cosmology.”
When the actual survey with the SKA comes online, a large team will be required to deal with it. Once the phase 1 of the SKA is built, around 2023, it will take about 2 years to complete the survey.
SKA SA has been crucial in promoting the build up of the required researchers to lead such an effort. However, says Santos, they don’t have to wait for the SKA to start, before doing observations. “Tests are already being conducted using the KAT7 system with the full support of the KAT7 staff and we plan to start tests with MeerKAT in just a year, during the early science phase,” Santos stated.
He added that the SKA telescope is like a “physics lab”, allowing many different experiments to be pursued. There will be other surveys that in combination with this one, will allow scientists to push the limits of our current knowledge of the Universe.