Telescopes here on Earth have detected signals that might help us solve an ongoing mystery, in a discovery that has astronomers very excited, but also puzzled.
In a study published in Nature last week, a group of astronomers announced that for the first time, they’ve detected multiple fast radio bursts, or FRBs, from the same source. But just what that source is, nobody knows.
Fast radio bursts are radio waves that come in short flashes, usually lasting just a few milliseconds. They must be produced by something out there in the universe, but it’s hard to pinpoint exactly what, especially because FRBs were only discovered in 2007, and until now, we’d detected just 16 of them.
Researchers have lots of ideas, though, based on what we know could send out short blasts of radio waves. Merging neutron stars, for example, might produce an FRB. Supernovas might do it, too. But most of those explanations don’t fit in this case. Because the bursts were seen more than once and from the same location — suggesting that they weren’t the result of a one-time event.
The series of bursts was spotted in May and June of last year. Researchers were using the Arecibo observatory in Puerto Rico to follow up on a fast radio burst that had been detected back in 2012. When they observed the area of the sky that the 2012 signal came from, they found a series of ten more bursts.
Events like neutron stars combining or a star going supernova can only happen once, so astronomers have ruled these out as possible causes. And to make things even weirder, there didn’t seem to be much of a pattern in the data.
The repeat signals were surprising and very exciting. I knew immediately that the discovery would be extremely important in the study of FRBs,
said Paul Scholz, who is a co-author of a paper.
The amount of time between the bursts wasn’t predictable — six of them came within ten minutes, while the others were more spread out. And each burst came in a different arrangement of frequencies of radio waves — in other words, their spectra were all different.
One possibility is that the signals are coming from an incredibly magnetic neutron star, called a magnetar, that’s sending out flares as its magnetic field shifts around.
The finding suggests that these bursts must have come from a very exotic object, such as a rotating neutron star having unprecedented power that enables the emission of extremely bright pulses,
It is also possible that the finding represents the first discovery of a sub-class of the cosmic fast-radio-burst population.
lead author Dr. Laura Spitler added:
Not only did these bursts repeat, but their brightness and spectra also differ from those of other FRBs,
It’s hard to know for sure without more data, so researchers will have to keep hunting for — and studying — more FRBs. But for now, the sources of these sudden bursts of radio waves are just another space mystery.
However, the apparent conflict between the studies could be resolved, if it turns out that there are at least two kinds of FRB sources,
said co-author Prof. Victoria Kaspi.
Canada’s CHIME telescope could help unravel the puzzle, adds Kaspi.
Thanks to the novel design of the soon-to-be completed apparatus, it is expected to be able to detect dozens of fast radio bursts per day, she says.
CHIME will further our quest to understand the origin of this mysterious phenomenon, which has the potential to provide a valuable new probe of the universe.