Mysterious space radio signals have finally been tracked to their source

Scientists have traced the brightest known fast radio burst to its origin in space, a milestone achievement they hope will provide clues about what's driving these mysterious cosmic flashes. 

The powerful signal, FRB 20250316A, was first spotted in March by the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, a radio telescope in British Columbia. The burst lasted less than one-thousandth of a second but carried more energy than the sun produces in four days. 

What set this event apart was what happened next. Using a new network of CHIME "Outrigger" stations — three miniature versions of the radio antenna in California, West Virginia, and British Columbia — researchers were able to home in on the burst’s location. That led them to a specific spot in the spiral galaxy NGC 4141, about 130 million light-years away in the Big Dipper constellation. 

Scientists say that kind of accuracy is unprecedented for a single burst of this magnitude. Amanda Cook, a McGill University researcher who led one of the studies, likened the precision to spotting a quarter from more than 60 miles away. 

"This result marks a turning point: Instead of just detecting these mysterious flashes, we can now see exactly where they’re coming from," Cook said in a statement. "It opens the door to discovering whether they’re caused by dying stars, exotic magnetic objects, or something we haven’t thought of yet."

Fast radio bursts, or FRBs, were first discovered in 2007, and thousands have been detected since. They are super-short flashes of radio energy from distant galaxies. Historically, they have vanished too quickly to analyze — faster than the blink of an eye — leaving their origins uncertain.

But this radio burst, nicknamed RBFLOAT for Radio Brightest Flash of All Time, was so powerful, it gave researchers that chance. Several teams quickly mobilized to investigate, producing two papers that appear in The Astrophysical Journal Letters. 

"It was so bright that our pipeline initially flagged it as radio frequency interference, signals often caused by cell phones or airplanes that are much closer to home," said Wen-fai Fong, a coauthor from Northwestern University, in a statement. "It took some sleuthing by members of our collaboration to uncover that it was a real astrophysical signal.”

The CHIME team provided the initial detection and pinpointed the signal’s origin. Astronomers at the W. M. Keck Observatory in Hawaii and the MMT Observatory in Arizona then studied the host galaxy and found that the burst came from just outside a star-forming region. Because the area was relatively clear of gas and dust, telescopes could get a rare, unobstructed view.

Meanwhile, scientists using the James Webb Space Telescope, a collaboration of NASA and its European and Canadian counterparts, examined the same spot in invisible infrared light and detected a faint glow. They think it could be a red giant — a puffed-up old star — or even residual heat from the radio blast itself. This marked the first time a possible stellar companion has been linked directly to a fast radio burst.

"This was a unique opportunity to quickly turn JWST’s powerful infrared eye on the location of an FRB for the first time," said Peter Blanchard, a Harvard researcher who led the Webb study, in a statement. "And we were rewarded with an exciting result — we see a faint source of infrared light very close to where the radio burst occurred. This could be the first object linked to an FRB that anyone has found in another galaxy."

The observations taken together point to magnetars — super-magnetic dead-star remnants — as leading candidates for producing RBFLOAT (Get it? Like a root beer float). CHIME researchers saw that the burst’s position, near a nursery of young stars, fits the mold of a magnetar that formed inside the stellar clump and drifted outward. 

CHIME collaboration astronomers observe construction of one of the three new Outrigger Telescopes in northern California. Credit: University of Toronto / Juan Mena-Parra

Still, Webb’s team cautioned that other explanations, such as activity in a binary star system, remain possible.

Adding to the intrigue, CHIME scientists reviewed six years of data and found no previous signals from this location. That suggests RBFLOAT may have been a one-time explosion, bolstering the idea that multiple catalysts could potentially trigger these bursts. Some fast radio bursts repeat often, while others, like this one, appear to be isolated events.

The achievement also showcases the growing capability of new telescope networks. By linking antennas, the CHIME/Outrigger system essentially functions as one giant continent-wide telescope. That allowed astronomers to shrink the uncertainty of RBFLOAT’s position to within 45 light-years — smaller than a single star cluster.

Scientists say this is just the beginning. CHIME is expected to trace hundreds of bursts each year. With Webb and ground-based observatories ready to follow up, astronomers hope to finally learn what powers these fleeting but colossal explosions.

"This bodes very well for the future," Fong said. "An increase in event rates always provides the opportunity for discovering more rare events."