Astronomers Caught Some of Space's Most Mysterious Radio Bursts in Real Time
Rare, unusual, and utterly cataclysmic, Fast Radio Bursts are among the most elusive unsolved mysteries in astronomy.
The intensity profile of the Fast Radio Burst. Image: Malesani/Petroff
For the first time ever, astronomers have captured an enormous radio wave burst in real time, bringing us one step closer to understanding their origins.
These fleeting eruptions, called blitzars or FRBs (Fast Radio Bursts), are truly bizarre cosmic phenomena. In the span of a millisecond, they emit as much radiation as the Sun does over a million years. But unlike other super-luminous events that span multiple wavelengths—gamma ray bursts or supernovae, for example—blitzars emit all that energy in a tiny band of the radio light spectrum.
Adding to the mystery is the rarity of blitzar sightings. Since these bursts were first discovered in 2007 with Australia's Parkes Telescope, ten have been identified, the latest of which was the first to be imaged in real time.
"In real time here means, 'as soon as the burst radiation arrives on the Earth,'" astronomer Daniele Malesani, co-author of a new paper about the discovery, told me over email. "The explosion occurred in fact a long time ago, as the radiation took a long time to reach us. But this delay is common to all kinds of light emitted by the burst, so if there is radiation at other wavelengths we would still be in time to catch it."
In other words, whatever is causing these Fast Radio bursts may also have emitted other kinds of light. That's why Malesani's team, led by Emily Petroff of Swinburne University of Technology, set out to essentially catch the blitzar red-handed. In this way, other telescopes could immediately image the burst's location to capture higher energy wavelengths before they dissipated.
"Before our study, the data was recorded by the instruments, but then nobody realized that the burst had occurred until much later, and we could not look for its counterpart at other wavelengths," Malesani explained. "Now, a software program continuously monitors the data as they are taken, and flags immediately any new fast radio burst. In this case, the burst was identified just ten seconds after it reached Earth."
The fast turnaround time yielded a few interesting results. Most pertinently, the supporting telescopes did not find a corresponding broad spectrum of wavelengths, though Malesani said that could just be a case of bad luck. "This was our first shot at attempting to locate the burst at other wavelengths, so we should certainly try again," he said.
But the team also found that the light from the burst was about 20 percent circularly polarized, meaning that it rotates in two planes rather than one. This is a puzzling finding, suggesting that blitzars originate from sources with incredibly strong magnetic fields. For example, they might be produced when neutron stars—which have the strongest magnetic fields in the known universe—undergo "starquakes" when the object's crust reconfigures itself. The intense magnetic fields surrounding black holes might also be producing these brief radio bursts.
Still, the riddle of these radio eruptions is far from solved. Malesani and his colleagues certainly narrowed down the options in their study, which was published in The Monthly Proceedings of the Royal Astronomical Society. In addition to the new findings, the team also confirmed that these events are enormous, cataclysmic and up to 5.5 billion light years distant. But to get the complete story, astronomers will need to keep searching for more blitzars to widen the data set on this strange cosmic occurrence.
"Right now, very few Fast Radio Bursts have been discovered," Malesani said. "But with time we will have more and their distribution in the sky will be a tool to understand better their origin."