Scientists from Northwestern University and McGill University have made a discovery that challenges existing theories about the origins of fast radio bursts (FRBs). The findings, published in the Astrophysical Journal Letters detail the observation of a fast radio burst originating from an ancient, quiescent galaxy, according to Phys.org.
The fast radio burst, designated FRB 20240209A, was first detected in February 2024 by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) observatory. Researchers successfully traced the source of this burst to the outskirts of a massive, elliptical galaxy that ceased forming new stars billions of years ago. This marks the first time a repeating FRB has been localized to such an old and inactive galaxy, as reported by Science Times.
FRBs are intense pulses of radio waves that last only milliseconds, yet in that fraction of a second, they release as much energy as our Sun emits in a year. Until now, these bursts had been predominantly associated with younger galaxies rich in star formation. The discovery of FRB 20240209A originating from an ancient galaxy challenges this prevailing notion, suggesting that the origins of FRBs might be more diverse than previously thought.
"The location of FRB 20240209A raises questions about how such energetic events can occur in regions where new stars are not forming," emphasized Vishwangi Shah, a graduate student at McGill University, according to Scienze Notizie. Shah and her colleagues are intrigued by the burst's origin, as it defies the common understanding that FRBs typically emanate from areas with intense star formation.
Further analysis revealed that the host galaxy of FRB 20240209A is approximately 11.3 billion years old and located two billion light-years away from Earth. Most of its stars formed over eleven billion years ago, and the galaxy is largely inert, with little to no new star formation taking place. Using telescopes at the W.M. Keck and Gemini observatories, researchers determined that the galaxy is extremely bright and has a stellar mass about 100 billion times that of the Sun, making it the most massive FRB source detected to date, as reported by Gizmodo.
"This discovery shows that when you think you've understood an astrophysical phenomenon, the universe surprises you," said Wen-fai Fong, according to Phys.org. Fong highlighted the excitement in time-domain astronomy, where observing transient events like FRBs continues to challenge and expand our understanding of the cosmos.
The observation of FRB 20240209A in such an unexpected environment suggests that there may be multiple pathways for the formation of these enigmatic bursts. Previously, most FRBs were thought to originate from magnetars—highly magnetized neutron stars formed from the core-collapse supernovae of massive stars—in regions of active star formation. The absence of young stars in the host galaxy of FRB 20240209A indicates that alternative mechanisms may be at play.
"Thanks to this new discovery, a picture is emerging that shows not all FRBs come from young stars. Maybe there is a subpopulation of FRBs that are associated with older systems," said Tarraneh Eftekhari, according to Observador. Eftekhari and her team suggest that these bursts could originate from magnetars formed through other processes, such as the merger of neutron stars or the accretion-induced collapse of white dwarfs in dense star clusters.
Between February and July 2024, FRB 20240209A flared up 21 times, indicating that it is a repeating source. This repetition allowed astronomers to pinpoint its location with greater precision. "Among the FRB population, this FRB is located the furthest from the center of its host galaxy," noted Shah, as per Gizmodo. This unusual position, far from regions of active star formation, underscores the need to revisit existing models of FRB origins.
"We do not know for a fact if there is a globular cluster present at the FRB position and have submitted a proposal to use the James Webb Space Telescope for follow-up observations of the FRB location," said Shah, according to Phys.org. Determining the presence of a globular cluster could support the hypothesis that the FRB originated from a dense collection of old stars, offering clues about alternative magnetar formation pathways.
"It seems to be the most massive host galaxy of an FRB to date," Eftekhari added, as reported by Phys.org. The galaxy's immense size yet inactive state makes it a subject for further study. The team's findings emphasize that the universe may harbor unknown complexities, and there are still many exciting discoveries to be made regarding FRBs.
"This dialogue with the universe is what makes our field of time-domain astronomy so incredibly thrilling," said Fong, highlighting the dynamic nature of astronomical research, according to Index. As scientists continue to observe and analyze these mysterious signals, they hope to unveil the secrets of the most extreme objects in the universe.
This article was written in collaboration with generative AI company Alchemiq