The Earliest High-Speed Radio Burst Illuminates Early Star Formation

A peculiar burst of light from the early universe aids astronomers in mapping elusive gases found between galaxies, much like flashlights in dark spaces.

The Fast Radio Burst (FRB) is an extremely brief yet potent burst of radio frequency emissions that has puzzled astronomers since its discovery in 2007. Currently, we know of only a few thousand instances in the universe, leaving much still to be understood about them, especially as most originate from galaxies neighboring the Milky Way.

Now, Manisha Kaleb from the University of Sydney, Australia, along with her research team, has identified a remarkably distant FRB, tracing back to a galaxy that existed merely 3 billion years post-Big Bang.

Kaleb and her collaborators first detected a burst designated 20240304B using the South African Meerkat Radio Telescope in March 2024, corroborating their findings with observations from the James Webb Space Telescope. They determined that the burst originated from a small, faint galaxy that appeared relatively youthful, characterized by rapid star formation.

“This discovery is extraordinarily distant,” stated Jason Hessel from the University of Amsterdam, Netherlands. The FRB 20240304B is from an epoch in the universe’s timeline known as the ‘midday’ of the universe, a period when the rate of new star formation peaks. This hints that during the galaxy’s formative years, this FRB—and possibly others—may have stemmed from a young star that underwent a supernova and collapsed into a magnetar, according to Hessel.

A key reason astronomers focus on FRBs lies in their ability to shine a light on ionized gases and lost electrons from radiation emitted by stars, which constitute most of the universe’s matter. Understanding its distribution is crucial for unraveling how larger structures—such as stars and galaxies—form. However, like the FRB, this gas remains largely invisible unless illuminated by a light source.

“This luminous flash reveals all the ionized material between us and the origin of the flash, allowing us to map both the gas and the magnetic fields amidst the stars and galaxies,” Hessel added.

The discovery of FRB 20240304B implies that the universe’s first stars were actively ionizing their surroundings, which can help establish a timeline of when these stars first ignited, according to Anastasia Fialkov from Cambridge University. The insights gleaned will only enhance with the detection of even more distant FRBs.

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