Plate Nº 27 · recorded October 9, 2026
Space & AstronomyReported finding
Webb Pins Down the Farthest Fast Radio Burst Ever Seen — and Its Odd Home
Astronomers used Webb to confirm the most distant fast radio burst ever seen, from just 3 billion years after the Big Bang, hosted by a dwarf galaxy 1,000 times less massive than expected.
By Elena Vasquez4 min read847 words
In brief
- Webb measured a redshift of 2.148 for the host of FRB 20240304B, placing the burst just 3 billion years after the Big Bang.
- The host galaxy is about 1,000 times less massive than typical FRB host galaxies.
- The MeerTRAP team detected the burst with the MeerKAT telescope on March 4, 2024.
- The study, led by Manisha Caleb of the University of Sydney, was published in the journal Science.
- The signal revealed a previously unknown galaxy cluster at redshift 0.3, about 3.5 billion light-years from Earth.
At a redshift of 2.148 — just 3 billion years after the Big Bang — astronomers have confirmed the most distant fast radio burst ever detected, and its host galaxy is nothing like they expected. NASA's James Webb Space Telescope revealed that the burst, designated FRB 20240304B, erupted inside a small dwarf galaxy roughly 1,000 times less massive than typical FRB hosts. The finding, published Thursday in the journal Science, tilts the evidence toward one leading theory of what powers these enigmatic flashes.
Fast radio bursts, first discovered in 2007, are millisecond-long flashes of radio emission from the distant universe. Most fire once and never repeat, and their origin remains one of astronomy's open questions.
"What makes fast radio bursts interesting is that we don't know what generates them," said Manisha Caleb of the University of Sydney, lead author of the study. "We have theories for what objects produce them, but we don't have conclusive proof."
How did astronomers find it?
The MeerTRAP team detected the burst on March 4, 2024, using the MeerKAT radio telescope in South Africa. The radio data suggested the burst was extremely distant — possibly the most distant one seen to date — but confirming that required identifying its host galaxy.
There was a problem. The team knew the burst's location on the sky very precisely, yet the world's largest ground-based telescopes could see no galaxy there. So they turned to Webb.
Two instruments did the job:
- NIRCam (Near-Infrared Camera) detected a faint galaxy at the right spot.
- NIRSpec (Near-Infrared Spectrograph) measured its redshift precisely: 2.148.
Redshift is a measure of how much the expansion of the universe has stretched a galaxy's light on its way to Earth; a higher redshift means a greater distance and an earlier time in cosmic history. The vast majority of FRBs detected so date occurred billions of years later than this one.
Why is the host galaxy surprising?
Most galaxies known to host FRBs are massive, star-forming galaxies. This one is not. The team found a dwarf galaxy actively forming stars, about 1,000 times less massive than expected.
"We thought it would be a big, nicely formed galaxy with lots of stars, and instead it was a little dwarf galaxy, although it was actively forming stars," Caleb said.
"The host sticks out in the whole galaxy sample that we have. And it definitely was not what we were expecting," said co-author Ben Stappers of the University of Manchester. "This combination of using the MeerTRAP project on the MeerKAT telescope to discover and localize these distant bursts and Webb to study their hosts is very exciting."
The galaxy existed during "cosmic noon," the period when star formation across the universe peaked. Its star-forming rate suggests most of its stars may have formed within just 30 million years — an extremely young stellar population.
What does this mean for the origin of FRBs?
The result bears on two competing theories:
- Neutron star mergers. Two orbiting neutron stars are expected to take billions of years to spiral together and collide, so FRBs from mergers should appear in older galaxies with more evolved stars.
- Magnetars. A magnetar — a young, highly magnetic neutron star — could produce an FRB quickly through processes akin to starquakes, shortly after its parent star explodes as a supernova. Such bursts should occur in young, star-forming galaxies.
The dwarf host of FRB 20240304B fits the magnetar picture, not the merger one.
"Our work suggests that it's very unlikely that this FRB was produced by a merger," Caleb said.
A cosmic flashlight through empty space
The burst also served as a probe of the matter between it and Earth. "A fast radio burst is almost like a cosmic flashlight. It lights up everything along the path," said co-author J. Xavier Prochaska of the University of California, Santa Cruz. "It carries an imprint of everything that it travels through, so you can use it to trace the 'cosmic web.'"
The signal carried the imprint of two cosmic structures:
- A previously unknown galaxy cluster at a redshift of 0.3, about 3.5 billion light-years from Earth.
- The nearby Virgo Cluster, about 54 million light-years away.
What comes next?
The team estimates MeerKAT could detect and localize several FRBs per year beyond a redshift of 1.0 — bursts from more than halfway back to the start of the universe. New radio facilities coming online may accelerate that pace, and Webb will be essential for characterizing their host galaxies.
"Our results further show the amazing capability of Webb where we can push boundaries beyond what was previously possible," said co-author Themiya Nanayakkara of the University of Sydney.
The findings rest on a single burst, so the case for magnetars over mergers is suggestive rather than settled. More distant FRBs — and more host galaxies — should tell.
Webb is the world's premier space science observatory, an international program led by NASA with its partners ESA (European Space Agency) and CSA (Canadian Space Agency).
via nasa.gov (Original)
More from Elena Vasquez
Nearby plates
- Astronomers Detect Most Distant Fast Radio Burst, 10 Billion Years Old
- A Mysterious Radio Signal Pointed at a Super-Earth. Was It Aliens?
- Faint Young Stars Suggest Messier 74 Is Nearly Twice as Large as Thought
- Astronomers Find the Lightest Double Neutron Star System Ever Measured
- CHIME Telescope Detects 9-Billion-Year-Old Hydrogen Signal