University scientists build telescope to find earliest galaxies

Detecting the first stars and galaxies in the universe not only takes a state-of-the-art telescope – it needs the quiet surrounds of the Western Australian desert.

The University of Melbourne is playing a key role in the development of a low frequency radio telescope, the Murchison Widefield Array (MWA), being built in the heart of the Western Australian desert. It is the only low frequency radio telescope in Australia.

Professor Rachel Webster, Head of Astrophysics in the University’s School of Physics has been instrumental in setting up the MWA with her colleagues from around the globe and Australia.

“Australia is the perfect location for radio telescopes as there are many remote and quiet areas of the desert – important criteria for building such sensitive technology,” she says.

The appeal of low frequency radio waves is their far-reaching emissions, which are providing hope to astronomers around the world to, for the first time, detect signals from the earliest galaxies.

Professor Stuart Wyithe is also a member of the team detecting signals from the earliest galaxies using the low-frequency radio technology.

“We know what happened at the beginning of the universe but we have never been able to observe it. This has been beyond the reach of the Hubble and other telescopes. Radio telescopes give us the opportunity to observe signals from long distances and may provide us with those answers of our earliest beginnings,” he says.

The Murchison Widefield Array is one of two radio telescopes which will act as precursors to the Square Kilometre Array (SKA) – the world’s largest and most sensitive radio telescope delving into the origins of the universe. Both are hosted at the Murchison Radio Observatory about 350 kilometers north-east of Geraldton in WA.

After a long-awaited announcement recently, the SKA will be hosted jointly between Australia and South Africa.

The SKA will be approximately one square kilometre giving 50 times the sensitivity, and 10,000 times the survey speed, of the best current-day telescopes.

“What we achieve at the MWA will pave the way for the SKA,” Professor Webster says. “The SKA will be larger and be able to delve deeper into the universe.”

Low-frequency telescopes are characterised by stationary antennae fixed into the ground.

Professor Wyithe and his team have provided theoretical models and predictions for what the types of signals the low-frequency telescope need to search for.

“We have predicted what the radio signals should look like and hence the telescope has been specifically designed to make those detections,” Professor Wyithe says.

The radio waves are measured from the hydrogen gas that surrounds the galaxies.

“The radio waves will tell us when the first galaxies appeared, how big they were and how many stars there were,” he says.

“We know this about nearby galaxies but don’t know when the first galaxies appeared.”

The team has been involved in developing real-time software aimed at capturing the data so that it can be sent to scientists for analysis.

“There are going to be very large sets of data that will come from this telescope and we have helped to set up methods for receiving that information,” Professor Wyithe says.

Professor Webster says their research will not just help inform us about the universe but will have other applications.

“We are learning about how to transport large amounts of data and analyse them for key information. This will have definite application in other fields such as medicine, for example,“she says.

It is hoped the Murchison Widefield Array will be fully operational within one year.

“We really need to test the technology, but as soon as this stage is finalised we will be making scientific measurements as fast as we can.

“Whatever we find is going to be very exciting.”

The MWA is an international collaboration between institutions from the US, Australia, New Zealand, and India, being led out of the Curtin University node of ICRAR, The International Centre for Radio Astronomy Research

http://www.physics.unimelb.edu.au