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Key takeaways
- Fast radio bursts (FRBs) are powerful, millisecond-long flashes of radio waves from space that occur every minute or two, each putting out more energy than the sun does in an entire year. But until now, astronomers have been unable to determine the exact origin of FRBs.
- A spectacularly bright FRB was detected in March from the direction of the Big Dipper by a transcontinental array of radio telescopes spanning North America—from British Columbia, down to Northern California, and out to West Virginia.
- The team behind this discovery nicknamed the FRB “RBFLOAT,” short for “Radio Brightest FLash Of All Time,” and they say this approach establishes a new way of studying these cosmic enigmas.
A team of international astronomers, including some at the University of California, Santa Cruz, have pinpointed the brightest fast radio burst (FRB) ever detected to a location in a nearby galaxy. The finding and the location surprised the team and offered new insight into FRBs, which are one of astrophysics’ biggest mysteries.
FRBs are powerful, millisecond-long flashes of radio waves from space. Researchers suspect that they are the result of extreme cosmic events but have, so far, been unable to determine the exact origin of any of them. FRBs are notoriously difficult to study because they vanish in far less than the time it takes to blink. For the past eight years, the CHIME radio telescope in British Columbia has been casting a broad net to catch thousands of these previously rare astrophysical events. Now it can also pinpoint their origin.
A spectacularly bright FRB, detected in March from the direction of the Big Dipper by the CHIME and formally referred to as “FRB 20250316A,” marks a significant change for researchers because it allowed for the identification of an exact point of origin using only the radio telescope. Their findings were published today in The Astrophysical Journal Letters.
The team, led by postdoctoral researcher Amanda Cook at McGill University, has affectionately dubbed their discovery “RBFLOAT,” short for “Radio Brightest FLash Of All Time.” Collectively, UC Santa Cruz’s contributions were significant, especially relating to identifying the host galaxy for the burst and using RBFLOAT’s local environment to constrain its origins.
Study co-author and UC Santa Cruz Science Division Dean Bryan Gaensler said this establishes a new way of doing FRB science. “Before now, we were detecting lots of FRBs, but only had crude information on where they were occurring in the sky,” Gaensler said. “It was like talking to someone on the phone and not knowing what city or state they were calling from. Now we know not only their exact address, but which room of their house they’re standing in while they’re on the call.”
‘Like spotting a quarter from 60 miles away’
To investigate RBFLOAT’s origin, the researchers relied on CHIME’s newly completed “outrigger” telescopes, which span North America from British Columbia, down to Northern California, and out to West Virginia. This array of vantage points gives CHIME unprecedented sharpness of vision, allowing astronomers to trace the burst to a region just 45 light years across—smaller than the average star cluster—in the outskirts of a galaxy about 130 million light-years away.
“The precision of this localization, tens of milliarcseconds, is like spotting a quarter from 60 miles away,” said Cook, Gaensler’s Ph.D. student when he was at the University of Toronto. “That level of detail is what lets us identify the host galaxy, NGC 4141, and match the burst with a faint infrared signal captured by the James Webb Space Telescope.”
Despite being the brightest FRB ever seen, researchers have not detected repeat bursts from the source, even in the hundreds of hours its position was observed by the CHIME survey instrument over more than six years. That goes against the prevailing idea that all FRBs eventually repeat.
New possibilities
The new observations are described through two studies: one is focused on the original radio discovery and localization of the burst, and the other on the James Webb Space Telescope’s near-infrared images of the exact location from which the radio burst originated. Together, these new data provide many new possibilities for studying FRBs, not just as cosmic curiosities but as tools to probe the universe.
“This marks the beginning of a new era where we can routinely localize even single, non-repeating bursts to pinpoint accuracy. That’s a game-changer for understanding what’s behind them,” said Mawson Sammons, a postdoctoral researcher at McGill. Sammons works with McGill astrophysicist and professor Victoria Kaspi, who co-leads the CHIME/FRB research team of roughly 100 scientists and students.
In addition to Gaensler, other UC Santa Cruz researchers who contributed to the study include Lordrick Kahinga, Lluis Mas-Ribas, and J. Xavier Prochaska.