A long time ago in a galaxy far, far away, a mysterious flash of energy was released into the universe.
Astronomers have now detected that flash, a burst of radio waves which travelled for more than 10bn years before reaching Earth – what they believe to be the most distant fast radio burst (FRB) ever recorded.
FRBs are intense bursts of radio waves that can emit as much energy in milliseconds as the sun does in months or years. These mysterious pulses were first discovered in 2007 and have puzzled scientists ever since, with speculation from some that they could have an alien origin.
In a new study published in Science, researchers have detected an FRB that originated when the universe was only about 3bn years old, meaning it has travelled through “approximately 80% of cosmic history”.
The burst, dubbed FRB 20240304B, is believed to be the farthest yet detected, more than double the previous distance record.
The scientists detected the burst using the MeerKAT radio telescope in South Africa, and subsequently identified its host galaxy using Nasa’s James Webb space telescope (JWST).
Dr Themiya Nanayakkara of the University of Sydney, one of the lead researchers on the paper, said when the burst was produced, “there was no Earth, there was no sun”.
Data from the JWST indicated that the burst originated from a “young, very small galaxy which is forming stars at a very high speed, with not many metals around it”.
There are several theories as to what the source of FRBs is, including that they originate from magnetars, neutron stars with a very powerful magnetic field.
“Whatever the mechanism that causes this radio burst has to account for that fact that it can be produced in … very young galaxies with very low amount of metals”, Nanayakkara said.
More than 10,000 FRBs have been detected since 2007. Some repeat continuously, Nanayakkara said, while “some of them repeat for a while and then stop … and then there are some FRBs that only go once and we never see again”.
Whether the new distant burst is a one-off flash or will yield recurrent signals remains to be seen.
But “the fun thing about FRBs is that we don’t need to know what is causing them to do some of the science we are doing now,” Nanayakkara said.
This particular burst “has been travelling for 80% of the age of the universe”, he said, adding that further detections of distant FRBs would enable scientists to map unseen matter in the distant universe.
Prof Matthew Bailes of Swinburne University, one of the astrophysicists who first discovered FRBs, described the new paper as “a validation of how powerful the FRBs are for probing the universe”.
Bailes described them as “a very fundamental way of counting how many atoms there are in the universe”. FRBs are affected by the particles they travel through, enabling scientists to quantify matter that cannot be seen through optical telescopes.
Dr Sara Webb, an astrophysicist also at Swinburne University who was not involved in the research, said: “You can use them essentially as a line-of-sight count for how much matter they had to go through [to get to Earth].”
The discovery suggests that “FRBs might have been very common in the early universe”, she added.
