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’s called a fast radio burst, or FRB. These massive bursts of radio waves usually last a few milliseconds. What sets this new signal apart is that it lasts up to three seconds. Deepening the mystery even further, this FRB was interspersed with periods of radio waves that repeated every 0.2 seconds in a clear pattern.
The signal, labeled FRB 20191221A, is the longest-lasting FRB ever detected. It also has the clearest periodic pattern ever seen in an FRB, according to MIT.
Although this signal may be localized to a specific distant galaxy, its exact source is not known. Currently, evidence suggests it originated from 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 supernovae. Their outer layers can peel off, leaving an incredibly dense little 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 fellow at MIT’s Kavli Institute for Astrophysics and Space Research, said in a statement. “Examples we know of in our own galaxy are radio pulsars and magnetars, which spin and produce a lighthouse-like radiated emission. And we think this new signal could be a magnetar or a 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 article with Michilli.
The signal was detected by the Canadian Hydrogen Intensity Mapping Experiment, or CHIME. This radio telescope, located in British Columbia, constantly monitors 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 he noticed something strange.
“It was unusual,” he said, according to MIT. “Not only was it very long, about three seconds, but there were remarkably precise periodic peaks, 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 flashes detected in this FRB could be from a neutron star that isn’t normally very bright when spinning, but for some reason ejected a large series of bursts. in a period of three seconds which CHIME proved to be able to catch.
“CHIME has now detected many FRBs with different properties,” Michilli said. “We’ve seen some that live inside very turbulent clouds, while others seem to be in clean environments. According to the properties of this new signal, we can say that around this source, there is a cloud of plasma which 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 gauge the rate of expansion of the universe.
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