Key Takeaways
- South Africa’s MeerKAT array detected FRB 20240304B in March 2024. Its signal traveled 10.8 billion years, making it the most distant fast radio burst yet recorded.
- The James Webb Space Telescope traced the burst to a dwarf galaxy where about 90% of stars formed within the last 30 million years, consistent with a newborn magnetar.
- Distortions in the signal revealed a previously unknown galaxy group about 3.5 billion light-years away, showing that FRBs can help map hidden intergalactic matter.
A fast radio burst that flashed for mere milliseconds has been in transit for 10.8 billion years, and it is forcing astronomers to revisit some comfortable assumptions. Spotted in March 2024 by South Africa’s MeerKAT array, FRB 20240304B comes from “cosmic noon,” when the universe was only about 3 billion years old. The surprise is not the signal’s intensity but its address: a dwarf galaxy where 90% of the stars formed less than 30 million years ago. To pin it down, researchers had to call in the James Webb Space Telescope, after visible light searches came up empty under the weight of an infrared shift.
What are fast radio bursts and why do they matter?
Every so often, the universe coughs up a blink-and-you-miss-it pulse of radio energy. These events, called fast radio bursts, last milliseconds, yet they carry clues about where matter sits in deep space and how stars live and die. Since the first find in 2007, astronomers have logged thousands, and still argue about what, exactly, makes them.
The leading suspect is the magnetar: a neutron star with an extreme magnetic field. Magnetars fit the profile because they can dump huge energy quickly, and some FRBs repeat in a way that feels consistent with a compact object. But the farther back you catch a burst, the harder it is to explain how its source formed so early.
FRB 20240304B: a signal that crossed most of cosmic history
That is why FRB 20240304B has researchers leaning in. Detected in March 2024 with MeerKAT, the 64-dish radio array in South Africa, the burst lasted about 0.001 seconds, standard for an FRB. What was not standard was the distance.
Based on the signal’s properties, the team concluded it traveled roughly 10.8 billion years to reach Earth, meaning it was emitted when the universe was only about 3 billion years old, during “cosmic noon,” the era when galaxies were forming stars at a furious pace. The results were published on October 8, 2026, in Science.
Why the James Webb follow-up changed the story
Pinpointing an origin is the hard part. Ground-based telescopes looked toward the patch of sky but came up empty, because the host galaxy’s light had been stretched into infrared by cosmic expansion. The team turned to the James Webb Space Telescope, which is built for that job (0.6 to 28.5 microns).
Webb’s images revealed a surprise: not a big, mature galaxy, but a dwarf galaxy about 1,000 times less massive than models would typically expect for a burst this powerful. Even more striking, researchers estimate that 90% of its stars formed within the last 30 million years, suggesting the FRB could plausibly come from a newly minted magnetar in a fresh star-forming region.
What this discovery means for the next wave of space science
Beyond the origin story, FRBs double as probes. As this burst crossed intergalactic space, lower radio frequencies were distorted by ionized gas, and the team used those fingerprints to infer a previously unknown group of galaxies about 3.5 billion light-years away.
If astronomers can collect more ultra-distant bursts like FRB 20240304B, FRBs may become a practical tool for mapping otherwise hard-to-measure matter between galaxies, and for stress-testing how quickly the early universe could build the kinds of compact, energetic objects we see today.
