October 7, 2022

Fast radio burst: Studies reveal details about the origin

3 min read

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

Recent research suggests that some FRBs originate from magnetars, which are neutron stars with very strong magnetic fields. A sharp radio burst was detected In the Milky Way According to a 2020 study, a magnet was attached.
But scientists have yet to pinpoint the origin of cosmic FRBs, billions of light-years away. It’s a problem that led an international team of scientists to see what they could learn from observations of nearly 1,900 bursts from an active fast radio burst source outside our galaxy called FRB 20201124A. a study Published on September 21 in the journal Nature.

The emission associated with FRB 20201124A lasted 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 world’s largest radio telescope — the China-based Five Hundred Meter Aperture Spherical Radio Telescope, or FAST.

During the first 36 days, the study team was surprised to see irregular, short-term variations of Faraday rotation measurements, which measure the magnetic field strength and particle density in FRB 20201124A’s surroundings. 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 author and astronomer Bing Zhang said in an email. said by

“This is not a reflection of the onset (lifetime) of FRBs,” said Zhang, founding director of the Center for Astrophysics at the University of Nevada, Las Vegas. “The FRB source has been around for a long time but is dormant most of the time. It wakes up occasionally (this time for 54 days) and emits a lot of bursts.”

The steps went up and down during this period, then stopped during the last 18 days before the FRB damped — “suggesting that the magnetic field strength and/or density along the approach around the FRB source “Time varies,” Zhang added. “This suggests that the environment of the FRB source is dynamically evolving, with the magnetic field or density or both rapidly changing.”

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“I think of it as making a movie around an FRB source, and our movie revealed a complex, dynamically evolving, magnetic environment never before imagined,” Zhang said in a news release. had gone.”

Oh Physical model A different team of researchers has proposed, based on observations of FRB 20201124A, that the FRB comes from a binary system about 8,480 light-years away that contains a magnetar and a B star, a star that is hot and massive and rotates faster than the Sun, according to a separate study published Sept. 21 in the journal Nature Communications.

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

They also discovered that the burst originated in a barred spiral galaxy, which is metal-rich and similar in size to the Milky Way, using the 10-meter Keck telescopes 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, causing It is less likely that the source is just a magnet at Peking University

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

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

“These observations brought us back to the drawing board,” Zhang said. “It is clear that FRBs are more mysterious than we imagined. Further multi-wavelength observing campaigns are needed to further unravel the nature of these objects.”

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