Sydney Astronomers Detect Most Distant Fast Radio Burst, Doubling Previous Record

A team of astronomers at the University of Sydney has detected a fast radio burst that travelled across more than ten billion years of space before reaching Earth—a signal so distant it originated when the Universe was barely three billion years old. The burst, catalogued as FRB 20240304B, shatters the previous distance record by more than double, opening a new window into how the cosmos evolved in its youth.

Fast radio bursts are among astronomy's enduring mysteries. They are violent, millisecond-long flashes of radio energy whose origins have long puzzled researchers. What makes them valuable is not their brevity but their power: they shine bright enough to be detected across cosmic distances, and the journey their light takes tells a story about everything it passes through. Led by Dr Manisha Caleb and Dr Themiya Nanayakkara, the Sydney team used South Africa's MeerKAT radio telescope to catch FRB 20240304B, then turned to NASA's James Webb Space Telescope to identify and measure the galaxy that produced it. The work appears in Science.

The host galaxy proved surprising. Rather than a massive, mature system, it turned out to be small and metal-poor, actively engaged in vigorous star formation. This detail matters because it points toward a specific origin story for at least some fast radio bursts: young magnetars, which are neutron stars born when massive stars explode as supernovae and possess extraordinarily strong magnetic fields. A young, star-forming galaxy is precisely the kind of environment where such objects would be born. The alternative theories—involving collisions between older neutron stars, for instance—would predict a different kind of host galaxy entirely.

Dr Laura Driessen, a co-author on the paper, noted that the discovery reveals not only where these bursts come from but also what they can teach us. The brief flash of radio light that crossed billions of years of space carried information encoded in it about the vast reservoirs of gas and matter between galaxies—material that is otherwise invisible to direct observation. As the signal travelled through cosmic history, it was shaped by every structure it encountered, making it a kind of cosmic probe of the Universe's hidden architecture.

The technical achievement was substantial. The host galaxy was too faint for the largest ground-based radio telescopes to identify on their own. Only the James Webb Space Telescope, with its infrared sensitivity and spectroscopic precision, could pinpoint it and measure its distance with confidence. This combination of instruments—sensitive radio detection paired with powerful infrared imaging—represents a new methodology for studying the early Universe through fast radio bursts.

Kavya Shaji, a PhD student involved in the research, suggested that the implications extend further still. Sufficiently powerful bursts could theoretically be detected from even earlier epochs, potentially reaching back to the Universe's first generations of stars. Dr Caleb emphasized that the team has now demonstrated the capability to identify and study fast radio bursts from when the Universe was young, a threshold that was not crossed before.

Professor Ben Stappers from the University of Manchester, who leads the MeerTRAP project at MeerKAT, framed the discovery as a beginning rather than an endpoint. The next frontier, he suggested, is to push even closer to those earliest stellar populations, using fast radio bursts as beacons to illuminate cosmic history. The work also underscores the role of the MeerKAT telescope, which is a precursor to the SKA Observatory currently under construction in Australia and South Africa. University of Sydney researchers are positioned to play leading roles in the scientific programs that the SKA will enable, promising even more powerful observations of the Universe's structure and evolution.