Student shows cosmic signals are the ‘real deal’
A CAASTRO PhD student has settled one of astronomy’s burning questions with a radio telescope near Canberra that she helped refurbish.
Manisha Caleb, who is enrolled at The Australian National University and works at Swinburne University, has confirmed that mystery bursts of radio waves astronomers have hunted for ten years really do come from outer space.
Caleb teamed up with her Swinburne colleagues to detect three of the ‘fast radio bursts’ with the University of Sydney’s Molonglo radio telescope 40 km from Canberra.
The bursts came from the direction of the constellations Puppis and Hydra.
“Because of the telescope’s characteristics, we’re 100 per cent sure the bursts came from space,” Caleb said.
Astronomers worldwide will be relieved. In 2015 other mysterious radio signals were tracked down to a microwave oven at CSIRO’s Parkes radio telescope.
The researchers’ certainty stems from the nature of the Molonglo telescope.
Until now all of the 20-odd ‘fast radio bursts’ known had been found with large dishes, such as the Parkes telescope. But unlike most dishes, Molonglo can see several spots or ‘beams’ on the sky at once.
“Local radio interference shows up in several of Molonglo’s beams. Cosmic signals never show up in more than three. That’s how we knew these signals were cosmic,” said one of Caleb’s co-supervisors, Dr Chris Flynn of Swinburne University.
Flynn and Caleb have been part of a Swinburne-led team that has overhauled the telescope in the last two years, rebuilding it into a machine for hunting the mystery signals.
Around the world other teams too are racing to find more bursts and identify their origins.
One of the new Molonglo bursts, FRB 160410, might be the closest one ever detected.
“We want to watch this one in particular to see if it repeats,” said Swinburne’s Professor Matthew Bailes, who also supervises Caleb.
“If it did, that would give us a better chance to pin down its location and link it to a galaxy,” he said.
“Understanding where the bursts come from is the key to understanding what makes them.”
The Molonglo telescope is blessed with a huge collecting area (18,000 square metres) and a large field of view (eight square degrees on the sky), which makes it excellent for hunting for fast radio bursts.
Over the next two years the telescope will be improved even more, gaining the ability to localise bursts to within five arcseconds on the sky. (An arcsecond is about the width of a human hair seen ten metres away.)
“Only one burst has ever been localised well enough to link it to a specific galaxy,” Caleb said.
“We expect Molonglo will do this for many more bursts.”
A paper on Caleb’s discovery has been accepted for publication in Monthly Notices of the Royal Astronomical Society.
‘The first interferometric detections of Fast Radio Bursts‘. Accepted for publication in Monthly Notices of the Royal Astronomical Society (2017). Online at https://arxiv.org/abs/1703.10173.
The ARC Centre of Excellence for All-sky Astrophysics (CAASTRO) is a collaboration between The University of Sydney, The Australian National University, The University of Melbourne, Swinburne University of Technology, The University of Queensland, The University of Western Australia and Curtin University, the last two participating together as the International Centre for Radio Astronomy Research (ICRAR). CAASTRO is funded under the Australian Research Council (ARC) Centre of Excellence program, with additional funding from the seven participating universities and from the NSW State Government’s Science Leveraging Fund.
Ms Manisha Caleb (ANU, Swinburne University, CAASTRO)
Ph: +61 402 145 680 E: firstname.lastname@example.org
Dr Chris Flynn (Swinburne University, CAASTRO)
Ph: +61 451 956 920 E: email@example.com
Professor Matthew Bailes (Swinburne University and ARC Centre of Excellence for Gravitational Wave Discovery)
Ph: +61 3 9214 8782 E: firstname.lastname@example.org
Helen Sim (CAASTRO)
Ph: +61 419 635 905 E: Helen.Sim@sydney.edu.au