The night sky viewed from the site of the Australian Square Kilometre Array Pathfinder in Murchison, Western Australia.

Australian research doubles number of known fast radio bursts

11 October 2018
Fast radio bursts emit as much energy as the Sun over 80 years in just a few milliseconds. Australian astronomers, including Professor Elaine Sadler are on the hunt to find more of these extraordinary objects.

Australian researchers using a CSIRO radio telescope in Western Australia have nearly doubled the known number of "fast radio bursts"; powerful flashes of radio waves from deep space.

The discoveries include the closest and brightest fast radio bursts ever detected.

University of Sydney astronomer Professor Elaine Sadler, who was part of the team, said: "At the moment, no one really knows what causes fast radio bursts, or why they are so powerful. Being able to find more of them to study is a really important step in working out what they are and why they happen."

The team’s findings were reported today in the journal Nature.

Fast radio bursts come from all over the sky and last for just milliseconds.

Scientists don’t know what causes them but it involves incredible energy – equivalent to the amount released by the Sun in 80 years in just a few milliseconds.

"We’ve found 20 fast radio bursts in a year, almost doubling the number detected worldwide since they were discovered in 2007," said lead author Dr Ryan Shannon, from Swinburne University of Technology and the OzGrav ARC Centre of Excellence.

"Using the new technology of the Australia Square Kilometre Array Pathfinder (ASKAP), we’ve also proved that fast radio bursts are coming from the distant universe rather than from our own galactic neighbourhood."

Professor Elaine Sadler.

Professor Elaine Sadler.

Professor Sadler from the University of Sydney’s School of Physics studied the optical images of the sky at the location of each of the radio burst.

While the exact location of each burst could not be pinpointed, she said that there was enough information to show statistically that they are not associated with galaxies in our local region of the Universe and must be far more distant. 

The closest one found in this survey is at least 100 million light years away. Most are much further.

Co-author Dr Jean-Pierre Macquart, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said most bursts travel for billions of years and occasionally pass through clouds of gas.

"Each time this happens, the different wavelengths that make up a burst are slowed by different amounts," he said.

"Eventually, the burst reaches Earth with its spread of wavelengths arriving at the telescope at slightly different times, like swimmers at a finish line.

"Timing the arrival of the different wavelengths tells us how much material the burst has travelled through on its journey.

"And because we’ve shown that fast radio bursts come from far away, we can use them to detect all the missing matter located in the space between galaxies – which is a really exciting discovery."

Doctoral candidate at the University of Sydney, Hao Qiu, helped design simulations to test and increase the efficiency of the detection software used in the study.

He said: "Using these simulations we were able to address several issues and raise detection efficiency by at least 10 percent.”

CSIRO’s Dr Keith Bannister, who engineered the systems that detected the bursts, said ASKAP’s phenomenal discovery rate is down to two things. He is Mr Qiu’s PhD supervisor.

"The telescope has a whopping field of view of 30 square degrees, 100 times larger than the full Moon," he said.

"And, by using the telescope’s dish antennas in a radical way, with each pointing at a different part of the sky, we observed 240 square degrees all at once—about a thousand times the area of the full Moon.

"ASKAP is astoundingly good for this work."

The team’s next challenge is to pinpoint the locations of bursts in the sky.

ASKAP is located at CSIRO’s Murchison Radio-astronomy Observatory in Western Australia and is a precursor for the future Square Kilometre Array (SKA) telescope.

The SKA could observe large numbers of fast radio bursts, giving astronomers a way to study the early universe in detail.

The researchers and their institutions acknowledge the Wajarri Yamatji as the traditional owners of the Murchison site.

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