Fast radio bursts (FRBs) are some of the most powerful signals in the universe. They can emit as much power in a few milliseconds as our Sun does in several days. Despite their strength, we still don’t have a definitive answer to what causes them. That is partly because, at least for the ones that only happen once, they are really hard to point down. But a new extension to the Canadian Hydrogen Intensity Mapping Experiment (CHIME) might provide the resolution needed to determine where non-repeating FRBs come from – and its first discovery was one of the brightest FRBs of all time, which helped researchers track it with an unprecedented level of precision, as described in a new paper in The Astrophysical Journal Letters.
CHIME has been in operation since 2018, but it only recently completed it’s new “Outrigger” extension earlier this year. The Outriggers, in this case, are miniaturized versions of the main telescope in British Columbia (about 66 km away from the main array), West Virginia, and California. These distances allow the system to create a very long baseline interferometer (VLBI), which is capable of analyzing differences in the signals received between the four stations to localize the sources of the FRBs they’re searching for.
In March, CHIME was able to capture a dream test case. A FRB named FRB20250316A, but colloquially named “radio-brightest flash of all time” (RBFLOAT), assumedly because the researchers were thirsty while trying to come up with a catchy name for their discovery, legitimately lived up to its name of being one of the brightest FRBs of all time. It also happened to come from a galaxy in our galactic neighborhood – NGC 4141, about 130 million light years away.
Fraser discusses FRBs, and what makes them so puzzling.
Given the new location information afforded by the CHIME’s new VLBI features, the researchers were able to narrow down this single burst to a more specific area than just a galaxy. They found it just outside of a star forming region on one of the galaxy’s spiral arms. Even more impressively, they narrowed it down to an accuracy of just 42 light years. That level of accuracy, given the 130 million light year distance, is impressive for any signal, but even more impressive for one that only lasted for a few milliseconds.
That precise localization allowed the researchers to take a look at the area using other observational resources both prior to the burst and after it. The Katzman Automatic Imaging Telescope (KAIT) and the Coddenham Observatory didn’t see any signs of a optical signal before the RBFLOAT signal, nor were any signals found after the event by Keck, Gemini, or MMT. CHIME itself also didn’t find another signal, despite monitoring the area for over 200 hours.
Since RBFLOAT lacked a repeating signal, it puts it into a category of single-burst FRBs, that might have a distinct cause from the less common repeating one that have typically been located with such precision. While single-burst FRBs are more common, given their transient nature it has been difficult to determine where precisely they came from, and therefore narrow down what might be causing them.
Video talking about Chime and it’s Outriggers and how they can revolutionize FRB astronomy. Credit – Caltech Astro Seminars YouTube Channel
Magnetars are a typical suggested cause, according to one theory at least. However, the RBFLOAT signal very clearly came from outside of an active star-forming region, where most magnetars would be expected. This could have been caused by the magnetar being gravitationally flung out of the nearby region or it could have formed there itself. Or this particular FRB could have been caused by something completely different.
Ultimately, even the researchers aren’t sure yet. But this particular discovery is a case study in how CHIME’s new Outrigger extensions will help locate and isolate even one-off FRBs. As the number of detections increases, patterns are more likely to emerge, and that’s when researchers might finally be able to answer the question of what causes the most powerful signals in the universe.
Learn More:
Eureka Alert / Northwestern University – ‘Root beer FLOAT’ burst’s home is located with extraordinary precision
The Chime / FRB Collaboration et al – FRB 20250316A: A Brilliant and Nearby One-off Fast Radio Burst Localized to 13 pc Precision
UT – Astronomers Detect Most Distant Fast Radio Burst Ever
UT – Fast Radio Bursts are Helping to Locate the Universe’s Missing Matter