“Breathtaking”: astronomers have discovered a “radio burst” from a very distant galaxy

It took eight billion years to get to us: astronomers have discovered an incredibly powerful explosion of radio waves in a very distant galaxy. According to a study published Thursday, a discovery that should help shed light on the mystery of this cosmic phenomenon. This “fast radio burst” called FRB (Fast Radio Burst), a burst of electromagnetic waves lasting less than a thousandth of a second, finally reached Earth on June 10, 2022, where an Australian telescope was able to pick up its signal.

It originated from a galaxy much more distant than previously recorded FRBs, as it traveled eight billion light years, precisely at a time when the Universe was less than half its current age, astronomers report in the journal Science. Since the first detection of such signals in 2007, scientists have wondered about the exact origin of the cosmic phenomenon, which is all the more difficult to determine because it is hidden.

Because these signals sometimes repeat, some initially speculated that we were dealing with radio communications transmitted through space by some kind of alien. More seriously, scientists believe the prime suspect is an incredibly dense dead star called a magnetar, with a super-strong magnetic field.

It’s “amazing” that the ASKAP telescope in western Australia was able to detect this FRB, Ryan Shannon of Australia’s Swinburne University in Melbourne, co-author of the paper, told AFP. “We were lucky to be able to observe this small dot in the sky for a millisecond after the eight billion years the pulse had traveled to capture it,” the astrophysicist adds.

The radio burst easily beat 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 emits in 30 years.

“Cosmic Web”

According to the scientist, hundreds of thousands of fast radio bursts can appear in the sky every day. But only a thousand have been discovered so far, and researchers have only been able to pinpoint the galaxy of origin for about fifty of them. However, it is a key element to understanding this phenomenon.

To determine the source of this distant radio burst, dubbed FRB 20220610A, researchers turned to the Very Large Telescope (VLT) in Chile. The latter showed that the signal came from a particularly dense galaxy that could have merged with one or two other galaxies, resulting in the formation of a strange magnetar.

But this is just scientists’ “best intuition,” Ryan Shannon emphasizes. Given that radio bursts have been detected in unexpected places, including inside the Milky Way, “it’s still unknown” what causes them, he notes.

Meanwhile, these radio bursts may help shed light on another mystery: the amount of solid matter in the Universe. It is thought to make up about 5% of the universe, with the rest made up of dark matter and dark energy. Problem ? More than half of this 5% solid is missing. Scientists believe it is in the cosmic web, thin threads of gas that connect galaxies together but are so diffuse they are invisible to telescopes.

Unless you’re using FRBs, which “bear the imprint of all the gas they’ve passed through,” the astrophysicist explains. This gas actually changes the wavelength of the FRB and thus allows the density of the latter to be measured.

According to the researcher, the FRB detected by the Australian telescope bears the imprint of “excess material”. Large numbers of these radio waves still need to be detected to refine calculations of the missing substance. In fact, new telescopes designed for radio astronomy are expected in the near future.