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.
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.”
“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.”
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
“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.”