Rapid radio bursts: Study reveals details about origins

Fast radio bursts, or FRBs, are bright, powerful emissions of radio waves lasting from a fraction of a millisecond to a few milliseconds long, each producing an energy equivalent to the Sun’s annual output.

Recent research suggested that some FRBs originate from magnetars, which are neutron stars with extremely strong magnetic fields. A loud radio burst was detected in the galaxy According to a 2020 study, one was attached to the magnetar.
But scientists have yet to trace the origins of cosmological FRBs, which lie billions of light-years away. It’s a question that prompted an international team of scientists to see what they could learn from observations of about 1,900 bursts from an active fast radio burst source outside our galaxy, called FRB 20201124A. one discovery Published September 21 in the journal Nature.

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

During the first 36 days, the study team was surprised to observe irregular, short-time variations of the Faraday rotation measurement, which measures magnetic field strength and particle density in FRB 20201124A’s surroundings. A large rotation measure means the magnetic field near the source of the radio burst is stronger, denser, or both, and a smaller measure means the opposite, study co-author and astrophysicist Bing Zhang said via email.

“This does not reflect the onset of the FRB (life span),” said Zhang, founding director of the Center for Astrophysics at the University of Nevada in Las Vegas. “The FRB source has been around for a long time but has been dormant most of the time. It wakes occasionally (this time for 54 days) and emits a lot of explosions.”

Measures moved up and down during that time period, then stopped during the last 18 days before the FRB became wet – “suggesting that the magnetic field strength and/or line of sight in the vicinity of the FRB source Densities are varying with time,” Zhang said. “This suggests that the atmosphere of the FRB source is evolving dynamically, with a rapidly changing magnetic field or density, or both.”

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“I equate it to filming a film of the surroundings of an FRB source, and our film revealed a complex, dynamically evolving, magnetic environment never imagined before,” Zhang said in a news release. Went.”

a physical model that a separate team of researchers formed based on observations of FRB 20201124A proposes that the FRB came from a binary system about 8,480 light-years away that has a magnetar and a Be star, a star that is hotter and larger and the Sun. According to a separate study published Sept. 21 in the journal Nature Communications.

The researchers found that the radio burst’s complex, magnetic environment is within about one astronomical unit (the distance between Earth and the Sun) from its source.

They also discovered that the explosion originated from a barred spiral galaxy, which is metal-rich and similar in size to the Milky Way, using the 10-meter Keck telescope at Mauna Kea, Hawaii. According to Nature study co-author Subo Dong, an associate professor at the Kavli Institute for Astronomy and Astrophysics, the source of the radio burst is located between the spiral arms of the galaxy, where no significant star formation is occurring, making it less likely It turns out that the origin is purely a magnet. at Peking University.

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“Such an environment for an isolated magnet is not directly expected,” Zhang said in a news release. “Something else could be around the FRB engine, possibly a binary companion.”

The authors said the modeling study should encourage further discoveries of fast radio burst signals from B star/X-ray binaries.

“These comments put us back on the drawing board,” Zhang said. “It is clear that FRBs are much more mysterious than we have imagined. More multi-wavelength observation campaigns are needed to further unveil the nature of these objects.”

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