A flash of radio light that lasted a few thousandths of a second has just done what no signal of its kind has done before: it crossed more than ten billion years of cosmic history and still reached us loud and clear.
The discovery, reported in the journal Science on October 8, belongs to astronomers using NASA’s James Webb Space Telescope. They traced the most distant fast radio burst ever found, catalogued as FRB 20240304B, to its home galaxy. It sits at a redshift of 2.148, meaning its light set out when the universe was roughly three billion years old, during the era astronomers call cosmic noon, when star formation was raging at its peak. The previous distance record for these bursts just got doubled.
The case of the missing galaxy
The trail starts on March 4, 2024, when South Africa’s MeerKAT array, 64 radio dishes spread across the Karoo desert, caught the flash. Its MeerTRAP project pinned down the position with unusual precision. Then the mystery began: archival sky images showed nothing there. The Keck Telescope in Hawaii looked. The MMT Observatory in Arizona looked. Nothing.
Enter Webb. Lead author Manisha Caleb of the University of Sydney and collaborator Themiya Nanayakkara secured discretionary observing time, the telescope’s fast lane for targets too good to wait. The Near-Infrared Camera found a speck at magnitude 28, exactly where the burst had been. The spectrograph confirmed the redshift. For the first time, a fast radio burst had a confirmed address in the universe’s youth.
A dwarf with a secret
Here is where the story took a turn nobody expected. Most fast radio bursts come from big, settled star-forming galaxies. This one came from a runt: a dwarf galaxy with about ten million times the mass of the Sun, roughly a thousand times lighter than the team expected, and it was making stars at a furious rate.
That single fact tilts the whole debate about what causes these bursts. Two theories dominate. One blames colliding neutron stars. The other blames magnetars, young neutron stars with absurd magnetic fields that occasionally have starquakes. The merger idea has a timing problem here: neutron star pairs usually need a billion years or more to spiral together and collide, but this galaxy’s stars look like most of them formed within 30 million years. There was simply no time for the slow dance. “Our work suggests that it’s very unlikely that this FRB was produced by a merger,” Caleb said. The magnetar theory, which thrives in exactly this kind of young, starbursting nursery, fits far better.
A flashlight pointed through deep time
There is a second payoff, and it may be the bigger one. As co-author J. Xavier Prochaska of UC Santa Cruz put it, a fast radio burst is almost like a cosmic flashlight: the signal collects fingerprints from everything it passes through. This one crossed about 80 percent of cosmic history and, along the way, revealed two structures, including a previously unknown galaxy cluster some 3.5 billion light-years from Earth and the nearby Virgo Cluster.
The empty stretches between galaxies are threaded with faint matter that is nearly impossible to see directly. A well-timed flash makes the invisible visible. That is the pattern to watch: no single instrument does it alone anymore. MeerKAT caught the flash, Webb found the galaxy, ground telescopes supplied the context. The next decade of discovery will look like this, a relay across continents and orbits, each player doing the part only it can do.
What happens next
One record does not close the case. Some bursts may still come from mergers; the universe is rarely in the mood for a single explanation. But Caleb’s team proved the hunt is possible even when the universe was young, which means the next record-breaker is a matter of patience, not luck. Somewhere out there, another millisecond of light is already on its way.
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