Mysterious Radio Bursts Traced to the Edge of an Ancient, Dying Galaxy

In February 2024, scientists on Earth detected a powerful radio burst from space. Trying to discover where it came from, they trace the brief flash of energy back to its extraterrestrial origin – and discover something unexpected.

Scientists led by Northwestern University and McGill University have discovered a fast radio burst (FRB) at the edge of an ancient elliptical galaxy. Scientists previously thought that these fast radio bursts, which produce more energy in a single flare than our Sun produces in an entire year, were produced exclusively by young galaxies that are constantly churning out new stars. Recent investigations, however, detail two sister Study Published on January 21st Astrophysical Journal Letters, prompting astronomers to reconsider the possible diversity of FRB sources

Dubbed FRB 20240209A, the February 2024 FRB wasn’t just a job. Between February and July 2024, the same source flared 21 times.

“The prevailing theory is that FRBs come from magnetos formed during core-collapse supernovae,” Northwestern University’s Tararaneh Iftekhari, who participated in both studies, said in a university statement. statement. Magnetars are neutron stars with very strong magnetic fields—and neutron stars are extremely small and dense celestial bodies that form following the explosive death of some massive star, that is, a supernova.

Iftekhari continued, “That doesn’t seem to be the case here. “While young, massive stars end their lives as core-collapse supernovae, we see no evidence of young stars in this galaxy. Thanks to this new discovery, a picture is emerging that shows that not all FRBs come from young stars. Maybe there is a subpopulation of FRBs associated with older systems.”

The old galaxy in question is 11.3 billion years old and 2 billion light years away from us. Using computer simulations, Iftekhari and his colleagues discovered that the galaxy is extremely luminous, and 100 billion times more massive than our Sun.

“This appears to be the largest FRB host galaxy to date,” Iftekhari said. “It’s one of the most massive galaxies out there.” The unusual FRB not only originated from an old galaxy, it also came from the edge of that galaxy — specifically, 130,000 light-years from its center.

“In the FRB population, this FRB is located [farthest] from the center of its host galaxy,” said McGill’s Viswangi Shah, who participated in both studies. “This is both surprising and exciting, as FRBs are expected to originate inside galaxies, often in star-forming regions. The location of this FRB so far outside its host galaxy raises the question of how such powerful events can occur in regions where new stars form. is not created.”

But FRB 20240209A isn’t the first FRB detected far from an active star-forming region—it’s the second. In 2022, astronomers detected the M81 FRB, located 12 million light-years from Earth, in a cluster of stars at the edge of the galaxy Messier 81.

FRB 20240209A “may be twin of M81 event [M81 FRB]. It is far from its home galaxy (far from where any stars are being born), and the stellar population in its home galaxy is extremely old. It was his high-day and is now approaching retirement,” said Wen-Fai Fong of Northwestern University, who participated in both studies. “At the same time, this kind of old environment makes us rethink our standard FRB progenitor models and turn to more exotic formation channels, which is exciting.”

One study suggests that, like the M81 FRB, the new FRB may originate from a cluster of stars, called a globular cluster.

“A globular cluster origin is the most likely scenario for this repeating FRB to explain why this FRBT is located outside its host galaxy,” explained Shah. “We do not know if a globular cluster is present at the FRB location and have submitted a proposal to use the James Webb Space Telescope for follow-up observations of the FRB location. If yes, this would make this FRB only the second FRB known to reside in a globular cluster. If not, then we have to consider alternative external scenarios for the origin of FRBs.”

In other words: back to the drawing board!