MIT scientists detect unusual radio signal from a distant galaxy

MIT scientists detect unusual radio signal from a distant galaxy

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Rapid radio bursts usually last a few milliseconds. Researchers found one that lasted much longer.

Using the CHIME radio telescope, astronomers discovered an unusual signal from a distant galaxy. CHIME, with background edited by MIT News

Astronomers from Canada and MIT have discovered an exciting and unusually sustained radio signal from a galaxy billions of light-years from Earth.

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

The signal, marked 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 can be located in a specific distant galaxy, its exact source is not known. Right now, evidence suggests that it comes from a radio pulsar or a magnetar, two types of neutron stars, according to the university. These are formed when stars that are more massive than the sun explode in a supernova. Their outer layers can blow off, leaving a small, incredibly dense core that continues to collapse. Gravity is so strong that protons and electrons combine to make neutrons, hence the name.

“There are not many things in the universe that send out strictly periodic signals,” Daniele Michilli, a postdoctoral fellow 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 a radiant 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. Calvin Leung, Juan Mena-Parra, Kaitlyn Shin and Kiyoshi Masui from MIT co-authored the paper with Michilli.

The signal was detected by the Canadian Hydrogen Intensity Mapping Experiment, or CHIME. This radio telescope, located in British Columbia, continuously looks at 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 read incoming CHIME data when he noticed something strange.

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

Michilli told MIT that the intense flashes detected in this FRB may be due to a neutron star that is not normally very bright when rotating, but for some reason hurled a large series of eruptions over a three-second period such as CHIME happened to be able to catch.

“CHIME has now discovered many FRBs with different properties,” said Michilli. “We have seen some living inside clouds that are very turbulent, while others look like they are in a clean environment. From the properties of this new signal, we can say 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 can be used as a way to measure the speed at which the universe expands.

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