Researchers spy a periodic fast radio burst
Fast radio bursts (FRBs) are some of the most enigmatic radio signals in the universe. They are incredibly short, lasting just a fraction of a second, and are astonishingly bright, emitting more energy than the Sun produces in a day. FRBs also show extreme diversity in their signals: Some repeat with regularity, while others are only ever seen once.
The origins of these mysterious signals remain disputed. While some FRBs come from a highly magnetic breed of stellar remnants known as magnetars, scientists aren’t sure if they account for every one. And although many thousands of FRBs have been recorded, the field is still young enough that a single event can turn our understanding on its head.
FRB 20191221A, which was spotted in late 2019 by the Canadian Hydrogen Intensity Mapping Experiment (CHIME), a radio telescope in British Columbia, Canada, is one such example. The discovery was reported July 13 in
First, it was the longest-duration FRB signal ever recorded, lasting roughly three seconds — about a thousand times longer than the average FRB.
If that wasn’t unusual enough, astronomers discovered structure within the FRB pulse itself. Specifically, hidden within the signal were at least nine distinct peaks, “like a heartbeat,” said co-author and
MIT postdoc Daniele Michilli in a press release. And these sub-components had startling regularity. “These peaks came at a precise period of about 0.2 seconds,” Michilli tells Astronomers have found several FRBs with embedded structure in the past, but FRB 20191221A is the first time the components themselves have been periodic.
Thus, whatever created the FRB must also be periodic. And while the analysis shows FRB 20191221A might originate from the usual suspect, the intensity of this FRB is more than a million times brighter than any seen before from a magnetar in our own Milky Way.
“We think this new signal could be a magnetar or pulsar on steroids,” Michilli explained in a press release.
The precise origin of the FRB remains unknown and, unfortunately, it seems so far like FRB 20191221A might be an isolated event. While astronomers can confirm the signal came from a galaxy billions of light-years away, the CHIME telescope field of view is such that it can only constrain the origin of an FRB to a patch of sky equivalent to the size of the Full Moon. This effectively means that researchers can’t precisely pin down the specific galaxy responsible for the signal.
Thankfully, this might not be the case for long. Currently, the CHIME collaboration is constructing three additional mission-supporting telescopes in British Columbia, California, and West Virginia. Within a year or two, the combined telescopes will allow the collaboration to pinpoint the location of every FRB signal to an area of sky the size of a quarter held at roughly 25 miles away. So, if FRB 20191221A bursts again, they’ll be ready.