CSIRO's Parkes radio telescope, which has been used to confirm a population of Fast Radio Bursts, is shown superimposed on an image showing the distribution of gas in our Galaxy. Credit: Swinburne Astronomy Production.
A single, gleaming flash of radio waves zooms toward us from halfway across the universe. Where it came from, nobody was sure, and it was gone in an instant.
The Lorimer burst, named after the astronomer who discovered it in a stack of half-a-decade old records, has stumped scientists for the last six years. But today a team of astronomers has announced that they've found four more flares just like it.
"You have to look at the sky for a very long time to find these," says Dan Thornton, the astrophysicist at the University of Manchester who discovered the new radio wave bursts. "The reason that we're detecting them now is we've simply looked long enough." Thornton and his colleagues have just published a paper in the scientific journal Science saying that these strange radio wave bursts are an entirely new astronomic phenomenon.
"Some people actually suspected the Lorimer burst was an atmospheric event," and a fluke measurement, says Manjari Bagchi, an astrophysicist at the International Centre for Theoretical Sciences, in Bangalore, India, who has also searched for these radio wave flares but was not part of the study. "But this proves that these are all natural phenomenon," Bagchi says.
Each flash of energy lasts only a few milliseconds, and researchers still don't know what causes them. "We think they're probably caused an explosive event, because we haven't seen them repeat," Thornton says. And pinpointing their exact origin is just about out of the question, given how rare they are and how big space is.
Thornton and his colleagues think a good bet for the burst's beginnings might be magnetars, which are rare and incredibly dense husks of past supernovae that are prone to occasional explosions of energy. "A magnetar can give off more energy in a millisecond than the sun in 300,000 years," Thornton says.
Whatever created them, Thornton's radio wave bursts hail from so far away that that they've taken half of the universe's life to reach us. "That's halfway to the big bang," Thornton says. That long travel leaves its mark on the radio waves: As the waves pass through charged particles in space, they're stretched out slightly. Thornton believes that even though we don't know the cause of the flares, by measuring that stretch and studying more of them, "we can use them to probe the material between us and the big bang."