“Outriggers” assisting a British Columbia-based radio telescope array helped a team of astronomers – including Canadians – find one of the brightest fast radio bursts (FRBs) ever known.
The find was made using the Canadian Hydrogen Intensity Mapping Experiment or CHIME, whose main array is based on the mountains of B.C. Tracing the FRB’s location, however, used CHIME’s “outrigger” telescopes that are in North American locations between British Columbia and California.
FRBs are incredibly brief (millisecond-long) bursts of radio waves. The advantage of CHIME is being an array of radio antennas, it allows researchers to scan a large area of sky and to cast a wide net for burst detection. The outrigger telescopes now are allowing researchers to figure out the location of these FRBs.
A burst in March, in the general direction of the Big Dipper, was found by the outriggers to be in a region of space that is roughly 45 light-years across – which is big by terms of measuring Earth, but is small astronomically as 45 light-years is less wide than the average cluster of stars.
The origin galaxy is roughly 130 million light-years away; by comparison, the closest stars to Earth are roughly four light-years from us, so this is a close-by event.
CHIME, dubbed the “most prolific FRB discovery machine” in a recent press release by McGill University, is thus moving into a new phase in which bursts can be pinpointed – providing more insight into how these explosions arose. The burst is officially named FRB 20250316A, but researchers nicknamed it “RBFLOAT” – for Radio Brightest FLash Of All Time, an apparent riff off the slang term “GOAT” (Greatest of All Time).
“This result marks a turning point,” said Amanda Cook, lead author of one of the studies concerning the discovery; Cook is also a postdoctoral researcher at McGill University in Montreal. “Instead of just detecting these mysterious flashes, we can now see exactly where they’re coming from. It opens the door to discovering whether they’re caused by dying stars, exotic magnetic objects, or something we haven’t thought of yet.”
Cook compared the “localization” of the FRB to finding a quarter 100 kilometers away – letting the researchers find the host, in a star-forming galaxy called NGC 4141. The FRB was also matched up with an infrared signal that the James Webb Space Telescope (which also has contributions from Canada) spotted, giving more data for the researchers.
In follow-up work, the Hawaii-based Keck Cosmic Web Imager provided information about the environment in which the FRB is found: “For the first time, we were able to constrain the gaseous environment the FRB originated from including its density, the gas composition and even the depth of the FRB in the gas inferred from the light emitted by hydrogen, oxygen and nitrogen,” Sunil Simha, a study co-author and joint Brinson Fellow at Northwestern University and University of Chicago, stated in another press release from Keck.
The spectroscopy from KWCI revealed how fast stars were produced in the galaxy, as well as gas amounts and density. JWST’s observations also allowed the researchers to see stars as individuals surrounding the FRB – a novel observation. This high detail was also possible in great part because the FRB is relatively close to Earth, which is a good opportunity for astronomers to learn more about the environments in which these bursts arise.
CHIME has not seen any repeat bursts from this area after hundreds of hours of observations across six years, which is another scientific thing of note – as FRBs have been believed to eventually repeat.
“We’re now re-examining some of the more explosive models that had fallen out of favour” to learn more about what might be happening, stated Mawson Sammons, a postdoctoral researcher at McGill. (Sammons works with astrophysicist Victoria Kaspi, who co-leads the CHIME/FRB research team.)
You can read the two studies in the Astrophysical Journal here and here.
