An international team of astronomers, including researchers from Northwestern University, has identified one of the brightest fast radio bursts (FRBs) ever observed and determined its origin with unprecedented accuracy. The FRB, named RBFLOAT (short for “radio-brightest flash of all time”), was detected using the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope array and its recently completed Outrigger array.
By combining data from sites in British Columbia, West Virginia, and California, scientists traced RBFLOAT to a spiral arm in a galaxy approximately 130 million light-years away. The location was pinpointed within 42 light-years—a level of precision not previously achieved for non-repeating FRBs.
FRBs are intense but brief flashes of radio waves that can emit more energy in milliseconds than the sun produces in four days. Most are difficult to detect due to their fleeting nature and distance from Earth. RBFLOAT was first observed in March 2025 and did not repeat after its initial burst.
“It is remarkable that only a couple of months after the full Outrigger array went online, we discovered an extremely bright FRB in a galaxy in our own cosmic neighborhood,” said Wen-fai Fong, senior author on the study and associate professor at Northwestern’s Weinberg College of Arts and Sciences. “This bodes very well for the future. An increase in event rates always provides the opportunity for discovering more rare events. The CHIME/FRB collaboration worked for many years toward this technical achievement, and the universe rewarded us with an absolute gift.”
“This result marks a turning point,” said Amanda Cook, corresponding author and postdoctoral researcher at McGill University. “Instead of just detecting these mysterious flashes, we can now see exactly where they are coming from. It opens the door for discovering whether they are caused by dying stars, exotic magnetic objects or something we haven’t even thought of yet.”
Further investigation using optical telescopes such as Arizona’s MMT telescope and Hawaii’s Keck II Telescope provided detailed information about RBFLOAT's environment. Researchers found that it originated along a spiral arm near—but not inside—a star-forming region populated by massive stars.
“We found the FRB lies at the outskirts of a star-forming region that hosts massive stars,” said Sunil Simha, postdoctoral scholar at Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). “For the first time, we could even estimate how deeply it’s embedded in surrounding gas, and it’s relatively shallow.”
“The FRB lies on a spiral arm of its host galaxy,” added Yuxin “Vic” Dong, graduate student at Northwestern University who led observations with MMT. “Spiral arms are typically sites of ongoing star formation, which supports the idea that it came from a magnetar. Using our extremely sensitive MMT image, we were able to zoom in further and found that the FRB is actually outside the nearest star-forming clump. This location is intriguing because we would expect it to be located within the clump, where star formation is happening. This could suggest that the progenitor magnetar was kicked from its birth site or that it was born right at the FRB site and away from the clump’s center.”
Magnetars—ultra-magnetized neutron stars formed by collapsing massive stars—are considered one possible source for some FRBs due to their strong magnetic fields capable of producing powerful bursts.
The new capability provided by CHIME's Outriggers allows astronomers to localize hundreds more FRBs each year than before—a significant advance compared to only about 100 well-localized events published over eight years prior.
“For years, we’ve known FRBs occur all over the sky, but pinning them down has been painstakingly slow,” Dong said. “Now, we can routinely tie them to specific galaxies, even down to neighborhoods within those galaxies.”
“The entire FRB community has only published about 100 well-localized events in the past eight years,” Simha said. “Now, we expect more than 200 precise detections per year from CHIME alone. RBFLOAT was a spectacular source to begin building such a sample.”
"Thanks to the CHIME Outriggers, we're now entering a new era of FRB science,” added Tarraneh Eftekhari, assistant director at CIERA.“With hundreds of precisely localized events expected in the next few years,we can start to understandthe full breadthof environmentsfrom whichethesemysterious signals emanate,b r i n g i n gusone stepcloserto unlockingtheir secrets.R B F L O A Tisjustthe beginning."
The research will appear on August 21st in The Astrophysical Journal Letters.The project received supportfrom organizationsincludingthe National Science Foundation,the Davidand Lucile Packard Foundation,the AlfredP.SloanFoundation,andseveralCanadianresearchinstitutions.TheCHIMEcollaborationbrings togetherastronomersfromNorthwesternUniversityandpartnerssuchasMcGillUniversity,the Massachusetts InstituteofTechnology,andothers.