MIT researchers detect unusual radio signal from distant galaxy

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Fast radio bursts usually last a few milliseconds. Scientists have found one that lasts 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 MITThe signal is what is known as the fast radio burst, or FRB. These very powerful bursts of radio waves usually 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 interrupted by periodic bursts of radio waves that repeated every 0.2 seconds in a clear pattern.

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

Although this signal can pinpoint the location of a particular distant galaxy, its exact source is unknown. Currently, evidence indicates that it came from a radio pulsar or a magnetar, two types of neutron stars, according to the university. These are formed when stars larger than the sun explode in a supernova. Its outer layers can explode, leaving behind a small, incredibly dense core that continues to collapse. The gravitational force is so strong that protons and electrons combine to form neutrons, hence the name.

“There aren’t many things in the universe that emit absolutely periodic signals,” said Daniele Michilli, a postdoctoral researcher at MIT’s Kavli Institute for Astrophysics and Space Studies. “Examples we know in our own galaxy are radio pulsars and magnetars that spin and produce a irradiated emission similar to 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. MIT’s Calvin Leung, Juan Mena-Parra, Kaitlyn Shin, and Kiyoshi Masui co-authored the paper with Michilli.

The signal was detected by the Canadian Hydrogen Density Mapping Experiment, or FRECKLE. Located in British Columbia, this radio telescope constantly watches the sky for radio waves emitted in the early universe. It is also sensitive to FRBs and has detected hundreds of these signals since 2018.

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

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

Michilli told MIT that the intense flares detected in this FRB could have been caused by a neutron star that wasn’t normally very bright as it rotated, but for some reason, CHIME emitted a large series of bursts in the three-second period that was possible. to hold.

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

Astronomers now hope to receive more periodic radio signals from this source, according to MIT. If so, the signals could be used as a way to measure the expansion rate of the universe.