Short, powerful bursts of radio waves from space are getting stranger and stranger. Astronomers have spotted 35 of these bursts from a single object with a pattern unlike any we have seen before.
at the SETI Institute in California and her colleagues observed this object, a fast radio burst (FRB) called FRB 20220912A, over the course of 541 hours of observation with the Allen Telescope Array in California. In each of the bursts from this FRB, they found a phenomenon called the 鈥渟ad trombone鈥� effect, where the frequency of the radio waves drops over the course of the burst.
The sad trombone effect has been seen before, but the bursts from FRB 20220912A displayed another pattern that was entirely new. When all the bursts had been observed, the researchers found that over time, the frequency and bandwidth of the bursts were dropping with respect to the ones before.
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鈥淭he sad trombone effect is a burst-by-burst effect 鈥� you can see it if you look at a single burst. But then in these sets of bursts, the frequency also appears to be decreasing,鈥� says , also at the SETI Institute and part of the team. 鈥淚t鈥檚 like a long sad trombone effect 鈥� a trombone that is being saddened over a really long period of time.鈥�
It is unclear what could cause this elongated sad trombone effect, especially because the cause of FRBs in general remains controversial. One leading explanation is that these bursts come from magnetars, which are spinning, highly magnetised neutron stars 鈥� that might end up fitting FRB 20220912A鈥檚 bursts, but no model has been able to account for all the behaviours of all the FRBs that have been observed.
鈥淢y understanding is that no one has really checked if the current magnetar models could explain the frequency decrease that we see, because it had never been observed before,鈥� says Sheikh. 鈥淭his FRB鈥檚 behaviour is still relatively consistent with magnetars 鈥� the question is which sub-class of magnetar models will be able to explain this behaviour.鈥�
arXiv
