Astronomers detect the brightest ever fast radio burst

A powerful blast of energy detected in March marks the brightest fast radio burst — a mysterious type of outburst from space — observed to date.

This ultrabright flash originated 130 million light-years from Earth, closer than most fast radio bursts, or FRBs, with pinpointed locations, allowing an in-depth investigation into what produced the puzzling signal. Two papers describe the findings in the Aug. 20 Astrophysical Journal Letters.

FRBs, first observed in 2007, are millisecond-long flashes of radio waves that typically release the same amount of energy that the sun does in a few days. Astronomers have detected about 4,000 unique FRBs, largely thanks to the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, a telescope array in British Columbia that constantly searches for FRBs.

On March 16, CHIME sensed a burst of electromagnetic energy about twice as bright as past record-holding FRBs, says astrophysicist Amanda Cook of McGill University in Montreal. “I had never seen anything like this.” She and her colleagues nicknamed it RBFLOAT, short for “radio brightest flash of all time,” in honor of a research group’s inside joke about the divisive taste of root beer.

RBFLOAT’s intrinsic energy is “dead average,” Cook says. But “since it was so bright, we knew it was very close,” because the waves lose energy as they travel to Earth. CHIME’s three auxiliary telescopes in British Columbia, West Virginia and California helped the researchers trace the FRB’s origin to a galaxy in the constellation Ursa Major.

The burst’s proximity allowed researchers to study RBFLOAT’s environment in detail. Data from other telescopes revealed that the FRB came from the edge of a young star-forming region. Additionally, researchers using the James Webb Space Telescope spotted infrared signals coming from the same area as RBFLOAT. “We have never detected some other type of emission at some other wavelength to really give us an idea of what could possibly be causing [FRBs],” says astrophysicist Peter Blanchard of Harvard University.

The infrared light may hint at a red giant star losing mass to a companion magnetar — a highly magnetized neutron star known to shoot beams of energy — which caused it to release an FRB, he says. Another possibility is that a magnetar ejected matter, producing an FRB along with X-rays and gamma rays, but that the latter wavelengths were absorbed by surrounding dust and re-emitted in infrared.

Researchers primarily suspect magnetars of pumping out the mysterious radio blasts, and these young astronomical objects track with RBFLOAT’s observed environment, Cook says.