Astronomers pinpoint radio flashes from a long time ago in a galaxy far, far away
An international team of astronomers have for the first time pinpointed the location of a so-called 'fast radio burst' - a type of short-duration radio flash of unknown origin - and have used this to identify its host galaxy over 3 billion light years away.
The team used radio telescopes in the European VLBI Network which includes the Lovell and Mark II Telescopes at Jodrell Bank, and presented their findings at the American Astronomical Society's winter meeting in Grapevine, Texas. The results appear today in Nature and the Astrophysical Journal Letters.
Prior to this discovery, astronomers had measured the properties of the radio emission from fast radio bursts (FRBs) to suggest that their sources lie far outside our own Milky Way galaxy. However, conclusive proof of their extragalactic origin has been lacking because poor determination of their exact position on the sky means their host galaxies could not be identified. This new discovery is also critical because it has allowed astronomers to precisely measure the distance to an FRB and so determine how much energy it is radiating.
FRBs are visible for only a fraction of a second, and have puzzled astronomers for over a decade since they were first discovered. Precise localization of an FRB on the sky requires high-resolution images to be made using networks of radio telescopes separated by large distances.
On Aug 23 2016, the Karl G. Jansky Very Large Array in New Mexico first detected a radio burst from the only known repeating FRB, named FRB 121102. This determined its sky position to a fraction of an arcsecond.
"Near this position, our team found both steady radio and optical sources, which arguably pointed the way to the galaxy hosting the FRB,” says lead author Shami Chatterjee (Cornell University, USA).
The team wanted to zoom-in even further, so they used the Arecibo Observatory and the European VLBI Network (EVN), which links telescopes in Europe and beyond, to provide a position for the FRB which is 10x more precise.
"With this level of precision, we have strong evidence that the source of the bursts is physically related to whatever is producing the persistent radio emission," says Benito Marcote (Joint Institute for VLBI in Europe, JIVE, Netherlands).
"It is the combined sensitivity of EVN telescopes, their large separation and the unique capabilities of the EVN central data processor at JIVE that allow for pinpointing events that are as short as a thousandth of a second, with a sky position accuracy of about 10 milli-arcseconds," adds Zsolt Paragi (JIVE).
"This is a wonderful example of the power of bringing together large telescopes in different countries to act as one planet-sized telescope, providing incredibly sharp images of the radio sky”, added Mike Garrett, Director of the University of Manchester’s Jodrell Bank Centre for Astrophysics and holder of the Sir Bernard Lovell Chair in Astrophysics.
Ben Stappers, leader of the Pulsars and Time Domain Astrophysics research group at Jodrell Bank commented, “Our Jodrell Bank telescopes, the Lovell and Mark II in this case but also the other five e-MERLIN antennas across the UK, regularly take part in EVN observations. This type of high-resolution imaging of transient radio sources is a key part of our science programme over the coming years.”
Read more about this story at the ASTRON website.
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