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MIT researchers have detected an unusual radio signal from a distant galaxy

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

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

Astronomers from Canada and the Massachusetts Institute of Technology have detected an intriguing and unusually strong radio signal from a galaxy several billion light-years from Earth.

According to the Massachusetts Institute of Technology, the signal is what is known as a fast radio burst or FRB. These powerful bursts of radio waves typically last a few milliseconds. What makes this new signal different is that it lasts up to three seconds. Further deepening the mystery, this FRB was punctuated by periodic bursts of radio waves that repeated every 0.2 seconds in a clear pattern.

The signal, designated FRB 20191221A, is the longest FRB ever detected. It also has the clearest periodic pattern ever seen in an FRB, according to the Massachusetts Institute of Technology.

Although this signal can be attributed to a specific distant galaxy, its exact source is unknown. According to the university, right now the evidence suggests that it comes from a radio pulsar or magnetar, two types of neutron stars. They are formed when stars more massive than the Sun explode in supernovae. Their outer layers can deflate, leaving a small, incredibly dense core that continues to break down. The force of gravity is so strong that protons and electrons combine to form neutrons, hence the name.

“There are not many things in the universe that emit strictly periodic signals,” said Daniele Michilli, a researcher at the Institute for Astrophysics and Space Research. Kavli of the Massachusetts Institute of Technology. “Examples we know in our own galaxy are radio pulsars and magnetars, which rotate and produce beacon-like beams. 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, Caitlin Shin, and Kiyoshi Masui of the Massachusetts Institute of Technology co-wrote the paper 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 in search of radio waves emitted in the early periods of the universe. It is also sensitive to FRB and has detected hundreds of such signals since 2018.

While still a researcher at McGill University in December 2019, Michilli was reading incoming CHIME data 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 intermittent spikes that were amazingly accurate, emitting every fraction of a second — boom, boom, boom — like a heartbeat. This is the first time the signal itself is periodic.”

Michilli told the Massachusetts Institute of Technology that the intense flares found in this FRB could come from a neutron star, which is not normally very bright when spinning, but for some reason emitted a large burst of flares over the three-second period that CHIME was able to detect. catch.

“CHIME has found many FRBs with different properties,” Michilli said. “We have seen that some of them live inside clouds, which are very turbulent, while others look like they are in a clean environment. Judging by the properties of this new signal, we can say that there is a plasma cloud around this source, which should be extremely turbulent.”

According to the Massachusetts Institute of Technology, astronomers are now hoping to get more periodic radio signals from this source. If they do, the signals could be used as a way to measure the rate at which the universe is expanding.


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