FRB 20220912A is a repeating fast radio burst that was discovered in 2022 and remained highly active for several months. Using the recently refurbished Allen Telescope Array, astronomers at the SETI Institute recorded 35 bursts from 541 hours of follow-up observations of the FRB 20220912A source over a period of two months and found that a fascinating pattern emerged.
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An artist’s impression of FRB 110523 reaching Earth; the colors represent the burst arriving at different radio wavelengths, with long wavelengths (red) arriving seconds after short wavelengths (blue). Image credit: Jingchuan Yu / Beijing Planetarium.
Fast radio bursts (FRB) are enigmatic and rarely detected bursts of energy that come from far beyond the Milky Way Galaxy.
These events have durations of milliseconds and exhibit the characteristic dispersion sweep of radio pulsars.
They emit as much energy in one millisecond as the Sun emits in 10,000 years, but the physical phenomenon that causes them is unknown.
To date, more than one hundred FRBs have been detected, yet only some of these have so far been observed to repeat.
Like most repeating FRBs, each burst from FRB 20220912A drifted from higher to lower frequencies over time.
But there was also a never-before-seen drop in the center frequency of the bursts, revealing what sounds like a cosmic slide-whistle when converted into a sonification using notes on a xylophone.
In it, most of the highest notes can be heard in the first few seconds and the majority of the lowest ones in the final seconds, as if the xylophone player is repeatedly hitting the lowest available bar on the instrument.
Astronomers think at least some FRBs are generated by a type of neutron star known as a magnetar, while other theories point the finger at colliding neutron star binaries or merging white dwarfs.
Dynamic spectra for all the bursts from FRB 20220912A detected using the Allen Telescope Array, the frequency-averaged pulse profiles, and the time-averaged spectra. Image credit: Sheikh et al. / SETI Institute.
“This work is exciting because it provides both confirmation of known FRB properties and the discovery of some new ones,” said Dr. Sofia Sheikh, lead author of the study.
“We’re narrowing down the source of FRBs, for example, to extreme objects such as magnetars, but no existing model can explain all of the properties that have been observed so far.”
Dr. Sheikh and her colleagues made their discovery after carrying out 541 hours of observations using the SETI Institute’s Allen Telescope Array.
They also tried to identify a pattern in the timings between the bursts but none was found, further illustrating the unpredictable and mystifying nature of these intense blasts of radio waves.
Nevertheless, the latest research is another step forward in the quest to unlock the secrets of FRBs, which generate as much energy in a thousandth of a second as our Sun does in an entire year.
“It has been wonderful to be part of the first FRB study done with the Allen Telescope Array,” Dr. Sheikh said.
“This work proves that new telescopes with unique capabilities, like the Allen Telescope Array, can provide a new angle on outstanding mysteries in FRB science.”
The team’s paper will be published in the Monthly Notices of the Royal Astronomical Society.
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Sofia Z. Sheikh et al. 2023. Characterization of the Repeating FRB 20220912A with the Allen Telescope Array. MNRAS, in press; arXiv: 2312.07756
