Oldest fast radio burst ever seen sheds light on early star formation

A strange flash of light since the start of the universe could help astronomers to map gas difficult to see between galaxies, like a flashbulb in a dark room.

The rapid radio gusts (FRB) are extremely short but powerful explosions of radio-frequency light which have perplexed astronomers since their first identification in 2007. A main theory is that they are produced by extremely magnetic neutron stars, called magnetiers. But because we only know a few thousand examples in the whole universe, with most from galaxies relatively close to the Milky Way, there are many things that we do not understand about them.

Now Manisha Caleb at the University of Sydney, Australia, and his colleagues have spotted an extremely distant FRB which comes from a galaxy which existed only 3 billion years after the start of the universe, which has billions of years more than the previous record holder.

Caleb and his team spotted the Rafale, called 20240304B, using the Meerkat radioelestope in South Africa in March 2024 and followed the source with observations of the James Webb space telescope. They discovered that the flash came from a small weak galaxy which seemed relatively young when the FRB was issued and had formed its stars quickly.

“It’s incredibly far away,” said Jason Hessels at the University of Amsterdam in the Netherlands. The FRB 20240304B comes from an era of the universe called Cosmic Noon, when the rate of formation of new stars was at its peak. This, with the young age of the galaxy at the time, could suggest that this FRB, and at least others, comes from young stars who had just exploded in the supernovae and collapsed in magnetars, explains Hessels.

One of the reasons why astronomers are interested in FRB is that the universe is full of ionized gas, which has lost its electrons due to the radiation produced by the stars. This gas constitutes the vast majority of all subjects in the universe, and understanding its distribution is essential to determine the formation of larger objects, such as stars and galaxies. But it is difficult to see unless there is a source of light that crosses it, like a FRB.

“This brilliant flash illuminates all the ionized material between us and where the flash is native, you can therefore use it to map the gas and the magnetic fields which are between the stars and the galaxies,” explains Hessels.

Because the FRB 20240304B was active at a time in the history of the universe when the first stars were formed and ionized the gas around them, we can use it to build a chronology when these stars were on for the first time, explains Anastasia Fialkov at the University of Cambridge. And that will only improve if we find FRBs even more distant.

The world capital of astronomy: Chile

Discover the astronomical strengths of Chile. Visit some of the most technologically advanced observatories in the world and Stargaze under some of the clearest heavens on the earth.