Franklin & Marshall College Associate Professor of Astronomy Fronefield Crawford is one of the astronomers that recently discovered repeating short-duration bursts of radio waves, another game-changer in the field of astronomy.
Crawford and his colleagues in Canada and Europe said the bursts are from an enigmatic source, likely located well beyond the edge of the Milky Way galaxy. The findings indicate that these “fast radio bursts” (FRBs) come from an extremely powerful object that occasionally produces multiple bursts in under a minute.
“This is an exciting development in this young, but rapidly evolving, subfield of astronomy,” Crawford said. “FRBs have been a bit of a mystery ever since they were first discovered. Nobody has observed them repeat in the same location, and these radio bursts are not coming from radio pulsars located within our galaxy. Something much more distant and energetic is most likely powering them.”
Until this discovery, reported in "Nature" this week, previously detected FRBs had appeared to be one-off events. Most theories about the origin of these mysterious pulses involved cataclysmic incidents that destroy their source – a star exploding in a supernova or a neutron star collapsing into a black hole.
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The Arecibo telescope and its suspended support platform of radio receivers is shown amid a starry night. Arecibo is the first telescope to see repeat bursts from the same source.
Image Credit: Danielle Futselaar
The new finding, however, shows that at least some FRBs have other origins. Crawford said, “With this new result, we move significantly closer to nailing down the source of these bursts. Some of them, at least, are not being produced in catastrophic annihilation events.”
FRBs last just a few thousandths of a second. They have puzzled scientists since they were first reported nearly a decade ago by a team that also included Crawford. Since then, 16 more FRBs have been discovered and published. Despite extensive follow-up efforts with telescopes around the world, astronomers until now have searched in vain for repeat bursts.
On Nov. 5, 2015, a McGill University doctoral student examined results from the Arecibo telescope in Puerto Rico, the world’s largest single aperture radio telescope. The data showed several bursts consistent with those of an FRB detected in 2012.
“Not only did these bursts repeat, but their brightness and spectra also differ from those of other FRBs,” said Laura Spitler, first author of the new paper and a postdoctoral researcher at Max Planck Institute for Radio Astronomy in Germany.
The 10 newly discovered bursts, like the one detected in 2012, have three times the maximum dispersion measure that would be expected from a source within the Milky Way. The team hopes to identify the radio bursts' galaxy of origin in future research.
“Finding the host galaxy of this source is critical to understanding its properties," said Jason Hessels, associate professor at the University of Amsterdam and the Netherlands Institute for Radio Astronomy, and corresponding author of the new paper.
“With this new result, we move significantly closer to nailing down the source of these bursts. Some of them, at least, are not being produced in catastrophic annihilation events.” -- Astronomy Professor Fronefield Crawford
