Astronomers discover the unexpected origin of a fast radio burst

(CNN) — More than 15 years after fast radio bursts were discovered, new research has revealed and deepened the mystery of the sources of these deep space phenomena.

Fast radio bursts, or FRBs, are bright, powerful emissions of radio waves that range from a fraction of a millisecond to a few milliseconds, and produce the equivalent of the Sun’s annual energy output.

Recent research suggests that some FRBs originate from magnetars, which are neutron stars with extremely strong magnetic fields. A fast radio burst found in the Milky Way was associated with a magnetar, according to a 2020 study.

But scientists have not yet identified the origin of cosmological FRBs, which lie billions of light-years away. It’s a dilemma that prompted an international team of scientists to see what they could learn from observations of nearly 1,900 bursts of an active source of fast radio bursts outside our galaxy called FRB 20201124A, according to a study published September 21 in the academic journal Nature.

fast radio burst

An illustration shows a fast radio burst (not the one detailed in the new studies). Credit: Mark Garlick/Science Photo Library/scipho/AP

Emissions associated with FRB 20201124A occurred for 82 hours over 54 days in the spring of 2021, making it one of the most active fast radio bursts known. It was visible through the world’s largest radio telescope: the Five-hundred-meter Aperture Spherical Radio Telescope, or FAST, located in China.

During the first 36 days, the study team was surprised to see short-lived and irregular variations in the Faraday spin measure, which measures the strength of the magnetic field and the density of particles in the surroundings of FRB 20201124A. A larger rotation measurement means the magnetic field near the source of the radio burst is stronger, denser, or both, and a smaller measurement means the opposite, study co-author Bing Zhang, an astrophysicist, said by email. .

“This does not reflect the beginning of the (life) of the FRB,” said Zhang, founding director of the Center for Astrophysics at the University of Nevada, Las Vegas. “The FRB source has been there for a long time, but it has been inactive most of the time. Every once in a while it wakes up (this time for 54 days) and emits many bursts.”

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The measurements went up and down during that period, and then stopped for the last 18 days before the FRB subsided “suggesting that the magnetic field strength and/or density along the line of sight in the vicinity of the FRB source vary over time,” Zhang added. “It suggests that the FRB source environment is dynamically evolving, with rapid changes in magnetic fields or density, or both.”

“I equate it to shooting a movie of the surroundings of an FRB source, and our movie revealed a complex, dynamically evolving and magnetized environment, something that had never been imagined before,” Zhang said in a press release.

A physical model developed by another team of researchers based on observations of FRB 20201124A proposes that the FRB originates from a binary system about 8,480 light-years away that contains a magnetar and a Be star, a hotter, more larger size that rotates faster than the Sun, according to an independent study published September 21 in the academic journal Nature Communications.

The researchers found that the complex magnetized environment of the radio burst is one astronomical unit (the distance between the Earth and the Sun) from its source.

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