MIT researchers detect an unusual radio signal from a distant galaxy

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Fast radio bursts typically last a couple of milliseconds. Scientists found one that lasted much longer.

Astronomers from Canada and MIT have detected an intriguing and unusually persistent radio signal from a galaxy several billion light-years from Earth.

According to MIT, the signal is what is known as a fast radio burst, or FRB. These massively strong bursts of radio waves typically last a few milliseconds. What sets this new signal apart is that it lasts up to three seconds. Further deepening the mystery, this FRB was interspersed with periodic bursts of radio waves that repeated every 0.2 seconds in a clear pattern.

The signal, named FRB 20191221A, is the longest-lasting FRB ever detected. It also has the clearest periodic pattern ever seen in an FRB, according to MIT.

While this signal can be pinpointed to a specific distant galaxy, its exact source is unknown. Right now, evidence suggests it came from either a radio pulsar or a magnetar, two types of neutron stars, according to the university. These form when stars more massive than the sun explode in a supernova. Its outer layers can blow away, leaving behind a small, incredibly dense core that keeps collapsing. The force of gravity is so strong that protons and electrons combine to form neutrons, hence the name.

“There aren’t many things in the universe that emit strictly periodic signals,” Daniele Michilli, a postdoctoral researcher at MIT’s Kavli Institute for Astrophysics and Space Research, said in a statement. “Examples that we know of in our own galaxy are radio pulsars and magnetars, which rotate and produce an emission similar to that of a lighthouse. And we think this new signal could be a magnetar or pulsar on steroids.”

The discovery of this FRB was reported in the journal Nature this week. Calvin Leung, Juan Mena-Parra, Kaitlyn Shin, and Kiyoshi Masui of MIT co-authored the paper with Michilli.

The signal was detected by the Canadian Hydrogen Intensity Mapping Experiment, or RING. This radio telescope, located in British Columbia, continuously watches the sky for radio waves emitted in the early periods of the universe. It is also sensitive to FRBs and has detected hundreds of these signals since 2018.

While still working as a researcher at McGill University in December 2019, Michilli was reading incoming data from CHIME when she noticed something strange.

“It was unusual,” he said, according to MIT. “Not only was it very long, lasting about three seconds, but there were periodic spikes that were remarkably precise, emitting every fraction of a second, boom, boom, boom, like a heartbeat. This is the first time that the signal itself is periodic.”

Michilli told MIT that the intense flares detected in this FRB could originate from a neutron star that normally isn’t very bright as it spins, but for some reason ejected a large series of bursts over a three-second period that CHIME could detect. capture.

“CHIME has now detected many FRBs with different properties,” said Michilli. “We have seen some that live inside clouds that are very turbulent, while others appear to be in clean environments. From the properties of this new signal, we can tell that around this source there is a cloud of plasma that must be extremely turbulent.” ”.

Astronomers now hope to pick up more periodic radio signals from this source, according to MIT. If they do, the signals could be used as a way to measure the rate at which the universe is expanding.