Fast Radio Burst Record Shattered by 10-Billion-Year Signal

A flash from the young universe

A millisecond-long flash of radio energy reached Earth after traveling for more than 10 billion years. Astronomers have now traced it to its source: a tiny, unusually young galaxy in the early universe. The signal, designated FRB 20240304B, was first picked up on March 4, 2024 by the MeerTRAP project using South Africa's MeerKAT radio telescope array. It is the most distant fast radio burst ever recorded, more than doubling the previous distance record, according to an announcement by the South African Radio Astronomy Observatory.

Fast radio bursts are brief, intense flashes of radio waves that last only a fraction of a second and release enormous amounts of energy. Their causes remain unsettled. First identified in 2007, most have been detected only once and never seen again, which is one reason the question of what produces them has been so hard to answer. This new record-breaker comes from an era when the universe was only about 3 billion years old, roughly a quarter of its present age.

The findings were published on October 8, 2026 in the journal Science, in a paper led by Dr. Manisha Caleb and Dr. Themiya Nanayakkara of the University of Sydney. Two of the most powerful observatories in existence worked together on the result. MeerKAT detected the burst and pinned down its position in the sky, but measuring how far away it was required finding the galaxy it came from. That galaxy proved too faint for the largest ground-based telescopes to see. It took the infrared instruments of NASA's James Webb Space Telescope to reveal it.

The tiny galaxy nobody expected

Webb's Near-Infrared Camera found a galaxy at exactly the spot the burst pointed to, and its spectroscopic measurements returned a redshift of 2.148, the cosmic yardstick that confirmed the record distance. What surprised the team was the galaxy itself. Most known fast radio bursts come from massive, well-established star-forming galaxies. This one came from a dwarf galaxy a thousand times less massive than the typical hosts.

Caleb said the team had expected "a big, nicely formed galaxy with lots of stars" but found "a little dwarf galaxy" instead, one that was actively forming stars. The little galaxy was in the middle of an intense growth spurt: evidence suggests most of its stars formed within just 30 million years, during an era astronomers call cosmic noon, when star formation across the universe ran at its peak.

The host's youth matters because it undercuts one of the leading models for how fast radio bursts are born. That model traces the bursts to pairs of neutron stars spiraling together and merging, a process that typically takes at least a billion years. The stars in this galaxy had simply not existed long enough for that to happen. The likelier source, the team reported, is a young magnetar, a neutron star with the strongest magnetic fields known in the universe, created in the explosive collapse of a massive star and later jolted by a violent "starquake."

A probe of the gas between galaxies

The burst is more than a mystery to solve. As a radio signal crosses the cosmos, it interacts with the thin ionized gas floating between galaxies, and those interactions leave their marks on the signal. MeerKAT caught this burst across frequencies from roughly 900 to 1,700 megahertz. Its intrinsic flash lasted about one millisecond, but by the time it reached Earth the signal had been smeared out to several milliseconds by the matter it had passed through. Because no other known burst has traveled so far, this signal carries the longest record yet of the invisible material filling the space between galaxies.

Caleb said the team had "caught a fast radio burst from a time when the universe was only about three billion years old" and had used that brief flash to study the matter the signal encountered on its long journey. The researchers were able to pick out imprints from multiple cosmic structures along the path, showing how future bursts could help map the universe's hidden structure.

The demonstration matters as much as the record itself. Caleb called the result exciting because it showed astronomers can now "identify and study an FRB from when the universe was young." Ben Stappers of the University of Manchester, a co-author of the study and principal investigator of the MeerTRAP project, said the next step is to "push this frontier further" to probe closer to the first generations of stars.

MeerKAT's combination of sensitivity to faint signals and precision in locating them means it could detect several bursts per year from the first half of cosmic history, according to the observatory. The Square Kilometre Array's SKA-Mid telescope, now under construction in South Africa and set to absorb MeerKAT, will extend that reach further, with Webb ready to identify the faint host galaxies. The earliest eras of the universe, long out of reach, are beginning to come into view.

Source: South African Radio Astronomy Observatory