In just one year of peering up at the Universe, a new telescope in Canada has quadrupled the number of fast radio bursts (FRBs) ever spotted.
First discovered in 2007, these immensely powerful flashes of radio waves last mere millisecond but are as brilliant as the brightest galaxies. They appear without warning from random points in the Universe, making it very difficult to predict them, trace them, or even pin down the cosmic phenomena that cause them.
Astronomers reckon they might be created by neutron stars or black holes – in fact, last year a FRB from our own galaxy was traced back to a magnetar.
But our understanding of these fast flashes has been limited, because we haven’t spotted very many. Until recently we’d only seen 140 bursts.
Now, the CHIME radio telescope in British Columbia, Canada, has announced that it detected 535 new FRBs in its first year of operation – quadrupling the known number.
Perhaps most intriguingly, the new observations reveal that FRBs fall into two classes: repeating and non-repeating. While most seem to be one-shot wonders, astronomers found 18 FRB sources that repeated, with each burst lasting longer and emitting more focused radio frequencies from the once-off FRBs.
This suggests that the different classes are created by different mechanisms, perhaps by different astronomical objects. It’s an exciting result because repeating bursts make it easier to pinpoint their origin, giving astronomers multiple chances to catch them.
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The team also found that the observed FRBs were distributed evenly across the sky, that they likely come from far-off galaxies, and that FRBs bright enough to be seen by current telescopes occur at a rate of around 9000 per day.
“That’s kind of the beautiful thing about this field – FRBs are really hard to see, but they’re not uncommon,” says Kiyoshi Masui, a CHIME collaborator from MIT. “If your eyes could see radio flashes the way you can see camera flashes, you would see them all the time if you just looked up.”
CHIME, which stands for the Canadian Hydrogen Intensity Mapping Experiment, is composed of four radio dishes that are each the shape and dimension of snowboarding half-pipes. The dishes don’t move to scan the sky like other telescopes – instead, CHIME relies on a correlator to focus incoming signals, working through seven terabits of data per second.
“Digital signal processing is what makes CHIME able to reconstruct and ‘look’ in thousands of directions simultaneously,” explains Masui. “That’s what helps us detect FRBs a thousand times more often than a traditional telescope.”
Another CHIME collaborator from MIT, Kaitlyn Shin, says that even as we work to understand what FRBs actually are, observing them may help us answer other questions about the Universe – such as the 3D structure of matter.
“Each FRB gives us some information of how far they’ve propagated and how much gas they’ve propagated through,” Shin says. “With large numbers of FRBs, we can hopefully figure out how gas and matter are distributed on very large scales in the universe. “
The results of CHIME’s first year of observation are being presented this week at the American Astronomical Society Meeting.