Mysterious fast radio burst in space has a ‘heartbeat’ pattern
Fast radio bursts, or FRBs, are intense, millisecond-long bursts of radio waves with unknown origins. The first FRB was discovered in 2007, and since then, hundreds of these quick, cosmic flashes have been detected coming from various, distant points across the universe.
Many FRBs release super bright radio waves lasting only a few milliseconds at most before disappearing completely, and about 10% of them have been known to repeat and have patterns.
This telescope, in operation since 2018, constantly observes the sky and, in addition to fast radio bursts, is sensitive to radio waves emitted by distant hydrogen in the universe.
Astronomers using CHIME spotted something on December 21, 2019, that immediately caught their attention: a fast radio burst that was “peculiar in many ways,” according to Daniele Michilli, a postdoctoral researcher in the Massachusetts Institute of Technology’s Kavli Institute for Astrophysics and Space Research.
The signal, named FRB 20191221A, lasted for up to three seconds — which is about 1,000 times longer than typical fast radio bursts.
Michilli was monitoring the data as it came in from CHIME, when the burst occurred. The signal is the longest-lasting fast radio burst to date.
“It was unusual,” Michilli said. “Not only was it very long, lasting about three seconds, but there were periodic peaks that were remarkably precise, emitting every fraction of a second — boom, boom, boom — like a heartbeat. This is the first time the signal itself is periodic.”
While FRB 20191221A has not yet repeated, “the signal is formed by a train of consecutive peaks that we found to be separated by ~0.2 seconds,” he said in an email.
An unknown source
The research team doesn’t know the exact galaxy from which the burst originated and even the distance estimate of a billion light-years is “highly uncertain,” Michilli said. While CHIME is primed to search for bursts of radio waves, it’s not as good at locating their origin points.
However, CHIME is being upgraded through a project where additional telescopes, currently under construction, will observe together and be able to triangulate radio bursts to specific galaxies, he said.
But the signal does contain clues about where it came from and what may have caused it.
“CHIME has now detected many FRBs with different properties,” Michilli said. “We’ve seen some that live inside clouds that are very turbulent, while others look like they’re in clean environments. From the properties of this new signal, we can say that around this source, there’s a cloud of plasma that must be extremely turbulent.”
When the researchers analyzed FRB 20191221A, the signal was similar to the emissions released by two different types of neutron stars, or the dense remnants after a giant star…
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