It took eight billion years to reach us: astronomers discovered an incredibly powerful explosion of radio waves in a very distant galaxy. A discovery that, according to a study published on Thursday, should help unravel the mystery of this cosmic phenomenon.
This “fast radio burst” called FRB (Fast Radio Burst), a flash of electromagnetic waves lasting less than a thousandth of a second, finally reached Earth on June 10, 2022, where an Australian telescope managed to receive its signal.
It came from a galaxy much further away than the previously recorded FRBs, spanning eight billion light-years, at a time when the universe was less than half its current age, astronomers reveal in Science magazine.
Since the first discovery of such signals in 2007, scientists have puzzled over the exact origin of the cosmic phenomenon, which is all the more difficult to determine because it occurs in secret.
Because these signals are sometimes repetitive, some initially assumed they were radio communications transmitted through space by an alien.
Seriously, scientists believe the prime suspect is an incredibly dense dead star called a magnetar with an ultra-strong magnetic field.
“It’s mind-blowing” that the ASKAP telescope in Western Australia managed to detect this FRB, Ryan Shannon of Australia’s Swinburne University (in Melbourne), co-author of the study, told AFP.
“We were lucky to be able to observe this small point in the sky for a millisecond after the pulse had taken eight billion years to be detected,” adds this astrophysicist.
The radio burst significantly exceeded the previous record, which traveled about five billion light-years. With incredible power, because in less than a millisecond the pulse released as much energy as the sun releases in 30 years.
“Cosmic Web”
According to the scientist, hundreds of thousands of fast radio bursts could occur in the sky every day. However, only a thousand have been discovered so far, and researchers have only been able to determine the source galaxy for about fifty of them. However, this is a key element in understanding the phenomenon.
To determine the source of this distant radio burst, called FRB 20220610A, researchers turned to the Very Large Telescope (VLT) in Chile.
The latter revealed that the signal came from a particularly dense galaxy that could have merged with one or two other galaxies, creating the strange magnetar.
But this is just the scientists’ “best intuition,” emphasizes Ryan Shannon.
Given that the radio bursts were detected in unexpected places, including within the Milky Way, it is “still unclear” what their cause is, he notes.
In the meantime, these radio bursts could help shed light on another mystery, namely the amount of solid matter in the universe. It is said to make up about 5% of this universe, with the rest made up of dark matter and dark energy.
The problem ? More than half of this 5% solids are missing. Scientists believe it lies in the cosmic web, which are thin threads of gas that connect galaxies but are so diffuse that they are invisible to telescopes.
Unless you use FRBs, which “carry the imprint of all the gas through which they have flowed,” explains the astrophysicist. This gas actually changes the wavelength of the FRB, allowing its density to be measured.
The FRB recorded by the Australian telescope bears the imprint of “excess material,” said the researcher. Large numbers of these radio waves still need to be recorded to refine missing matter calculations.
In fact, new telescopes for radio astronomy are expected soon.