Astronomers in eastern Australia using the CSIRO's 64-m Parkes radio telescope have for the first time caught a "fast radio burst" live. A fast radio burst is a short, sharp flash of radiowaves from an unknown source. Scientists hope that the finding, published this month in Monthly Notices of the Royal Astronomical Society, will bring us closer to understanding the phenomenon.
The first such radio burst lasted only milliseconds and was discovered in 2007 by astronomers combing the Parkes data archive for unrelated objects. Six more bursts coming from outside our galaxy have now been found with the Parkest data, and a seventh with the Arecibo telescope in Puerto Rico.
"These bursts were generally discovered weeks or months or even more than a decade after they happened! We're the first to catch one in real time," said Emily Petroff, a PhD candidate co-supervised by CSIRO and by Swinburne University of Technology in Melbourne, Australia, which is a member institution of the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO).
Believing she would spot a live burst, Petroff had an international team ready to make rapid follow-up observations. When the burst went off, the team sprung into action using twelve telescopes around the world including Australia, California, the Canary Islands, Chile, Germany, Hawaii, India, and in space.
No optical, infrared, ultraviolet or X-ray counterparts, however, happened to show up. "That in itself rules out some possible candidates, such as long gamma-ray bursts and nearby supernovae," said team member Dr. Mansi Kasliwal of the Carnegie Institution in Pasadena, California. These bursts could be low-energy gamma-ray bursts, giant flares from distant magnetars, or even an imploding neutron star.
One of the big unknowns is the exact distances of these fast radio bursts. The characteristics of the radio signal and how it traveled through space indicate that this latest burst was up to 5.5 billion light years away.
"That means it could have given off as much energy in a few milliseconds as the Sun does in a day," said team member Dr. Daniele Malesani of the University of Copenhagen.
The burst left a clue to its origin, as well. The Parke's real-time detection system captured its polarization -- the direction that these waves vibrate. The radio emission from the latest bursts was 20% polarized, indicating there are magnetic fields near the source. Identifying the origin, however, is only a matter of time Petroff says.
"We've set the trap. Now we just have to wait for another burst to fall into it."
