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It lasted only a fraction of a second, but it travelled for more than 10 billion years to reach us. Astronomers have now detected and pinpointed the most distant fast radio burst ever recorded, opening a new window onto a universe that was still young.
What are fast radio bursts?
Fast radio bursts, or FRBs, are intense flashes of radio waves that release enormous energy in just milliseconds. According to reports from the University of Sydney team published in the journal Science, these bursts are among the most mysterious signals in astronomy, because they are so brief and their exact origins are still debated.
The new record holder is designated FRB 20240304B. It was first picked up by South Africa's MeerKAT radio telescope through the MeerTRAP project, led by researchers Dr Manisha Caleb and Dr Themiya Nanayakkara. The harder problem was figuring out where such a fleeting flash actually came from.
How did scientists trace something so far away?
Ground-based telescopes, even the largest, saw nothing at the burst's position. The breakthrough came when NASA's James Webb Space Telescope used its NIRCam instrument to find the host galaxy, and its NIRSpec instrument to measure the galaxy's redshift at 2.148. That places the burst at a time when the universe was only about 3 billion years old, more than doubling the previous distance record for a pinpointed FRB.
Surprisingly, the host turned out to be a small dwarf galaxy, roughly a thousand times less massive than expected, yet actively forming stars. Researchers say most of its stars may have formed within just 30 million years, which is very recent in cosmic terms.
Why does one tiny flash matter so much?
Because the burst's light, actually radio waves, had to cross billions of light-years of space to reach Earth, it carries fingerprints of everything it passed through. By studying how the signal was changed along the way, astronomers can learn about the otherwise invisible matter spread between galaxies, which is extremely hard to observe directly.
The youth of the host galaxy also offers a clue about what creates these bursts. If stars formed so recently before the burst appeared, the source is more likely to be a young, highly magnetic neutron star called a magnetar, rather than a slow merger of old neutron stars, which would take billions of years to happen.
In short, a millisecond flash from the early universe is now acting like both a torch and a probe, showing us where it was born and illuminating the dark space it crossed to reach us.
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