Astronomers have traced a fast radio burst (FRB) to an ancient, elliptical galaxy for the first time. This discovery challenges previous assumptions that FRBs originate only from regions with active star formation. The research, led by Northwestern University and McGill University, was published in the Astrophysical Journal Letters.
"The prevailing theory is that FRBs come from magnetars formed through core-collapse supernovae," said Tarraneh Eftekhari of Northwestern University. "That doesn’t appear to be the case here." The findings suggest a possible subpopulation of FRBs associated with older systems.
Wen-fai Fong, also from Northwestern, noted the unexpected nature of this discovery: "This new FRB shows us that just when you think you understand an astrophysical phenomenon, the universe turns around and surprises us."
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) detected the new FRB, named FRB 20240209A, in February 2024. Unlike typical FRBs, which are brief and powerful radio blasts lasting milliseconds, this event repeated itself multiple times over several months.
Researchers used telescopes at W.M. Keck and Gemini observatories to study the surrounding environment of the FRB. They found it originated near an 11.3-billion-year-old galaxy located two billion lightyears from Earth. This galaxy is extremely massive—100 billion times the mass of our sun—and represents one of the most massive known hosts for an FRB.
Vishwangi Shah from McGill University highlighted how unusual it is for an FRB to be located so far from its host galaxy's center: "This is both surprising and exciting."
Before this finding, only one other similar case had been documented in 2022 involving Messier 81 (M81). Fong commented on these similarities: "In fact, this CHIME FRB could be a twin of the M81 event."
The possibility exists that this new repeating FRB originated within a dense globular cluster—a promising site for magnetars formed through mechanisms other than core-collapse supernovae.
"A globular cluster origin for this repeating FRB is the most likely scenario," Shah explained. Further observations using the James Webb Space Telescope may confirm or refute this hypothesis.
Eftekhari concluded by emphasizing ongoing opportunities for discovery: "It's clear that there's still a lot of exciting discovery space when it comes to FRBs."
The studies were supported by various institutions including NASA and The Canadian Natural Sciences and Engineering Council of Canada.