NASA’s James Webb Space Telescope has traced the most distant known fast radio burst to a small, young galaxy, strengthening the case that a highly magnetic stellar remnant produced it. For astronomers trying to explain these brief cosmic flashes, the galaxy’s youth helps narrow the possible culprits.
The signal, named FRB 20240304B, reached South Africa’s MeerKAT radio telescope on March 4, 2024. Webb later identified its host and measured its redshift, the stretching of light as the universe expands, placing the event just 3 billion years after the Big Bang. The paper gives a redshift of 2.148 ± 0.001, more than twice the previous record’s 1.016 ± 0.002 for FRB 20220610A, measured in Ryder and colleagues’ Science paper. The 3 billion years describes the universe’s age when the burst occurred; the signal then traveled for roughly 10 billion years before reaching Earth. Ground observations at Hawaii’s Keck Observatory had found no visible host, helping the researchers make their case for Webb observing time.
The galaxy’s age narrows the suspects
The host was roughly 1,000 times less massive than the researchers expected, according to the ESA/Webb release. The research preprint estimates its stellar mass at roughly 10 million times the Sun’s mass, but its age depends on the model: one places half its stellar mass formation within the last 10 million years, another within the last 30 to 100 million years. That leaves little room for the long wait associated with one proposed explanation: two neutron stars gradually spiraling together before colliding.
A young magnetar, a neutron star with an intense magnetic field, fits that timeline better. It can emerge after a massive star explodes, potentially producing radio flashes without the lengthy delay of a merger. This is evidence favoring an explanation, rather than a confirmed identification: lead author Manisha Caleb says researchers still lack conclusive proof of what generates these bursts.
There’s a timing distinction, too. NASA announced the Science publication on October 8, but the team had already posted a preprint describing the burst and its redshift in August 2025. That preprint is Manisha Caleb and colleagues, “A fast radio burst from the first 3 billion years of the Universe,” arXiv:2508.01648, submitted August 3, 2025.
NASA says the team expects radio telescopes to locate more distant bursts, with Webb needed to study their host galaxies. Those hosts’ stellar ages could test whether distant bursts consistently occur soon after stars form, as the young magnetar explanation predicts. Would finding a distant burst in a galaxy dominated by old stars change your view of that explanation?
Sources
- 1.Webb Measures Distance to Farthest Fast Radio Burst, Suggesting Origin · NASA
- 2.Webb measures distance to farthest fast radio burst, suggesting origin · ESA/Webb
- 3.Astronomers use Webb telescope to pinpoint host galaxy of the most distant fast radio burst to date · University of California, Santa Cruz
- 4.A fast radio burst from the first 3 billion years of the Universe · arXiv
- 6.A fast radio burst from the first 3 billion years of the Universe · arXiv
- 7.A luminous fast radio burst that probes the Universe at redshift 1 · arXiv
Reported by the WattsUpNext desk from the sources linked below. Spot an error? Tell us at corrections@wattsupnext.com.
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