In February 2024, scientists on Earth detected a powerful radio blast from space. Trying to find out where it came from, they tracked the brief energy flash to an extraterrestrial source and discovered something unexpected.
Scientists led by Northwestern University and McGill University tracked fast radio bursts (FRBs) to the edge of an ancient elliptical galaxy. Scientists have previously believed that such quick radio bursts, which produce more energy in a single flare than our sun does in a year, are produced exclusively by young galaxies that are steadily producing new stars. I thought it would happen. However, recent research elaborates on two points: younger sister the study Published on January 21st Astrophysics Journal Letters, Astronomers are urging us to reconsider the potential diversity of FRB sources.
The February 2024 Fed, known as FRB 20240209A, was not just a one-and-done deal. Between February and July 2024, the same source exploded 21 times.
“The leading theory is that FRBs originate from magnetars formed by collapsing supernovae,” Taraneh Eftekhari of Northwestern University, who participated in both studies, said at the university. statement. Magnetars are neutron stars with very strong magnetic fields, and neutron stars are very small, dense objects that are thought to form in the wake of the explosive death of several large stars, or supernovae. .
“That doesn’t seem to be the case here,” Eftekari continued. “Young, massive stars end their lives as core collapse supernovae, but we see no evidence of young stars in this galaxy. This new discovery confirms that not all FRBs come from young stars. It’s becoming clear that there may be a subpopulation of FRBs that are 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, Eftekari and her colleagues discovered that this galaxy is extremely bright and 100 billion times more massive than our Sun.
“This appears to be the most massive FRB host galaxy yet,” Eftekari said. “It’s one of the most massive galaxies in the world.” This unusual FRB not only originates from an old galaxy, but also from the edge of that galaxy, specifically 130,000 light-years away from its center. did.
“Among the Fed population, this Fed [farthest] said Vishwangi Shah of McGill, who participated in both studies. “This is both surprising and interesting because FRBs are expected to occur inside galaxies, often in star-forming regions. It is surprising that this FRB is located so far outside the host galaxy. , raising the question of how such an energetic event could occur in a region where no new stars are forming.”
However, FRB 20240209A is not the first FRB detected far from regions of active star formation, but only the second. In 2022, astronomers tracked M81 FRB 12 million light-years from Earth and determined it was a star cluster at the edge of the Messier 81 galaxy.
FRB 20240209A “Possibly a twin of the M81 event” [M81 FRB]. It is far from its home galaxy (and far from where stars are born), and its home galaxy’s star population is very old. Their prime years have passed and they are now well on their way to retirement,” said Wen-Fai Fung of Northwestern University, who participated in both studies. “At the same time, this kind of ancient environment is forcing us to reconsider the standard FRB ancestry model and look to more exotic formation channels, which is exciting.”
One study suggests that, like the M81 FRB, the new FRB may have arisen from a population of stars called a globular cluster.
“The globular cluster origin of this repeating FRB is the most likely scenario explaining why this FRB is located outside of its host galaxy,” Shah explained. “Although we do not know for a fact whether a globular cluster exists at the FRB’s location, we have submitted a proposal to use the James Webb Space Telescope for follow-up observations of the FRB’s location. If so, this FRB This would be only the second FRB known to exist within a globular cluster. If not, we would need to consider other exotic scenarios for the origin of FRBs.”
In other words, you’re back to square one.
