Astronomers pinpoint the most distant fast radio burst ever detected

Astronomers have detected and traced the most distant fast radio burst ever recorded, a powerful flash of radio waves that traveled for more than 10 billion years across the cosmos before reaching Earth.

Fast radio bursts (FRBs) are among the most mysterious phenomena in astronomy. Lasting only milliseconds, they release enormous amounts of energy, but their origins remain uncertain.

The discovery, led by researchers Dr. Manisha Caleb and Dr. Themiya Nanayakkara at the University of Sydney, is published today in the journal Science.

The MeerTRAP project used South Africa’s MeerKAT radio telescope to detect the burst, designated FRB 20240304B, before identifying its host galaxy using observations from NASA’s James Webb Space Telescope.

The burst originated when the universe was only about 3 billion years old, making it the most distant FRB yet detected and more than doubling the previous distance record. The finding gives astronomers a powerful new way to study both the evolution of galaxies and the vast, otherwise invisible matter that fills the space between them.

“This is an extraordinary glimpse into the distant universe,” said Caleb from the Sydney Institute for Astronomy in the School of Physics.

“We have caught a fast radio burst from a time when the universe was only about 3 billion years old, and we have used that brief flash of radio light to learn about the matter it has traveled through over billions of years.”

A small galaxy offers clues to origins

By combining sensitive radio observations with powerful infrared imaging and spectroscopy, the team was able not only to detect the burst but also to identify the galaxy that produced it.

The host galaxy turned out to be an unexpected source.

“The galaxy hosting this burst is surprisingly small, metal-poor and undergoing a very active episode of star formation,” said Dr. Laura Driessen, a co-author at the University of Sydney.

“That gives us an important clue about the environments in which FRBs are born and shows that these brief radio flashes can tell us not only about the distant universe but also about how galaxies and their stellar populations evolve.”

The research provides fresh evidence that at least some FRBs may originate from young magnetars, highly magnetized neutron stars formed when massive stars explode in supernovas. The newly discovered host galaxy is young and vigorously forming stars, characteristics more consistent with magnetar formation than alternative theories involving the merger of older neutron stars.

Reaching toward the first generations of stars

The result pushes the boundaries of how far astronomers can use fast radio bursts as probes of the universe.

“In principle, sufficiently powerful bursts could be detectable from the very early universe,” said Kavya Shaji, a co-author and a doctoral student in the School of Physics.

Caleb said, “What is particularly exciting about our result is that we’ve now demonstrated that we can identify and study an FRB from when the universe was young.”

Co-author professor Ben Stappers from the University of Manchester is also principal investigator of the MeerTRAP project at the MeerKAT telescope. He said, “The next step is to push this frontier further and see how close we can get to the first generations of stars.”

The host galaxy was invisible to the largest ground-based telescopes, requiring the unique capabilities of the James Webb Space Telescope to pinpoint it and measure its distance.

“Our results further show the amazing capability of the Webb space telescope where we can push boundaries beyond what was previously possible,” said Nanayakkara, who recently joined the University of Sydney.

A beacon for matter between galaxies

Beyond setting a new distance record, the burst acted as a cosmic beacon, illuminating the vast reservoirs of gas and matter between galaxies. As the radio signal traveled across most of cosmic history, it carried information about the material it encountered along the way, allowing researchers to study structures that are otherwise difficult to observe directly.

In 2023, university astronomers were also involved in the discovery of what was then the most distant fast radio burst, a record now surpassed by FRB 20240304B.

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