Astronomers pinpoint the source of the brightest one-off fast radio burst ever

FRBs are powerful flashes of radio waves from space that last a thousandth of a second. Researchers suspect they result from extreme cosmic events, but until now they have not succeeded in determining their exact origin. FRBs are notoriously difficult to study because they vanish in the blink of an eye. For several years, the Canadian CHIME/FRB radio telescope has been able to capture these rare astrophysical events. Now, for the first time, the origin has also been determined using only the CHIME telescope.

The particularly bright FRB 20250316A (also called RBFLOAT – Radio Brightest FLash Of All Time), was detected in March by CHIME. “This result marks a turning point: instead of just detecting these mysterious flashes, we can now see exactly where they come from. We can now begin to discover whether they are caused by dying stars, exotic magnetic objects, or something we haven’t thought of yet,” says Amanda Cook, a postdoctoral researcher at McGill and leader of one of the two accompanying studies.

To investigate the origin of FRB 20250316A, the researchers used the recently completed CHIME ‘outrigger’ telescopes, which span North America from British Columbia to California. These telescopes have very high spatial resolution, allowing them to trace the burst to an area just 45 light-years wide—smaller than an average star cluster—in the outskirts of a galaxy approximately 130 million light-years away.

“To achieve this precision, it is necessary to combine signals from radio telescopes thousands of kilometers apart. For this, we must measure when the FRBs arrive with an accuracy of one billionth of a second,” says Nina Gusinskaia, a Bell Burnell fellow at ASTRON. “Because we managed to accomplish this, we were able to link the burst to a faint infrared signal captured by the James Webb Space Telescope (JWST).”

Although it is the brightest FRB that CHIME has ever observed, it is not a repeating flash. CHIME has observed the source position for hundreds of hours over more than six years. This finding contradicts the prevailing view that all FRBs ultimately repeat.

Two relatively small radio telescopes in the Netherlands confirm this picture. The Dwingeloo Radio Telescope and one dish of the Westerbork Synthesis Radio Telescope (WSRT) have together stared at the burst location for more than 200 hours. Omar Ould-Boukattine, PhD student at ASTRON and UvA: “Our team began an observation campaign within a day of the news of the burst, allowing us to rule out any ‘aftershocks’.”

Victoria Kaspi, professor at McGill (Montreal, Canada), and co-leader of the CHIME/FRB research team of approximately one hundred scientists, adds: “This FRB appears energetically different from the repeating FRBs we know. We are now examining models that we had previously dismissed.”

The new observations are described in two studies: one focuses on the original discovery and localization, the other on JWST near-infrared images of the location where the flash originated. Together, they provide details and new possibilities for studying FRBs, not only as cosmic curiosities but also as instruments for exploring the universe.

“This is just the beginning. We are now zooming in on multiple FRBs per week with this precision, and this will teach us tremendously about this enigmatic phenomenon,” concludes Ziggy Pleunis, assistant professor at the UvA.

‘FRB 20250316A: A Brilliant and Nearby One-Off Fast Radio Burst Localized to 13 parsec Precision’ by the CHIME/FRB Collaboration, is published in The Astrophysical Journal Letters. DOI: 10.3847/2041-8213/adf62f

‘James Webb Space Telescope Observations of the Nearby and Precisely-Localized FRB 20250316A’ is published in The Astrophysical Journal Letters. DOI: 10.3847/2041-8213/adf29f