Fast radio burst detected in 'dead' galaxy raises questions about mysterious signals

USA Today

27-01-2025

With their extremely strong magnetic fields, magnetars have long been considered the prime culprit capable of producing the powerful bursts of energy known as fast radio bursts.
The recent burst, called FRB 20240209A, throws that theory into question. Now, astronomers must consider that not all fast radio bursts come from younger galaxies and stars.
The powerful burst was also traced to an unprecedented 130,000 light-years from its associated galaxy's center, where few other stars exist.
Fast radio bursts, strong pulses of energy detected in radio-wave frequencies, may be a common phenomenon in the cosmos, but their enigmatic origins are something astronomers are only beginning to understand.
Take, for instance, one such fast radio burst astronomers recently tracked to the distant outskirts of a long-dead galaxy.
Based on what scientists thought they knew about fast radio bursts, referred to in astronomy as FRBs, this type of galaxy should not contain the kind of star long thought to produce such bursts. The surprising source of the repeating burst has baffled astronomers, who haven't considered that regions in which no stars are forming could produce such a radio flare.
Detailed in two related studies led by researchers at Northwestern University and McGill University, the discovery "shatters assumptions that FRBs solely emanate from regions of active star formation," according to a press release announcing the research findings. The groundbreaking find, the researchers claim, could reshape our understanding of the universe and its most powerful and mysterious signals.
"Just when you think you understand an astrophysical phenomenon, the universe turns around and surprises us,' Wen-fai Fong, an astronomer at Northwestern who was a senior author on both studies, said in a statement. 'This 'dialogue' with the universe is what makes our field of time-domain astronomy so incredibly thrilling.'
What are fast radio bursts? Magnetars believed to be the cause
Astronomers have been studying fast radio bursts from across the universe since 2007 when the first millisecond-long burst was discovered.
The bright burst of electromagnetic radiation may be brief, but fast radio bursts are so powerful that they produce more energy than what our sun emits in an entire year, astronomers say.
The flashes of radio energy emanate from distant galaxies, with the most distant and most powerful ever observed being found 8 billion light-years away and documented in a 2023 study. While many fast radio bursts are isolated events, those that repeat sporadically become of interest to astronomers, who set their sights on pinpointing those bursts to study them further.
Observations have allowed astronomers to determine that the most likely culprit behind these cosmic flashes are magnetars. With their extremely strong magnetic fields, these neutron stars – small, dense collapsed cores of supergiant stars – are capable of producing the powerful bursts of energy that have been observed for years.
Fast radio burst traced to 'dead' galaxy
The recent burst, called FRB 20240209A, throws that theory into question.
The flare was first detected in February 2024 with a newer radio telescope called the Canadian Hydrogen Intensity Mapping Experiment (CHIME.) After it was initially spotted, the radio burst pulsed another 21 times through July at the same source – six flares of which were also detected by a smaller outrigger telescope located 37 miles away from CHIME's main station in British Columbia.
Further observations allowed the team of astronomers to trace FRB 20240209A to a region of space associated with an 11.3-billion-year-old galaxy that no longer forms stars. The researchers believe the flares may have originated in a cluster of old stars orbiting the dead but "extremely luminous" galaxy – located 2 billion light-years from Earth and weighing more than 100 billion times the mass of the sun.
What's perplexing, the researchers said, is that the magnetar in the galaxy should have disappeared long ago.
The discovery forced the team to conclude that not all fast radio bursts come from younger galaxies and stars and that perhaps some originate from older systems, said Tarraneh Eftekhari, an astronomer at Northwestern who led one of the studies and coauthored the other.
FRB traced unprecedented 130,000 light-years from host galaxy
If the region believed to be the source of the flare is indeed a globular cluster, where old, dead stars are bound together by gravity, it would make the radio burst just the second ever to originate from such a location, said Vishwangi Shah, a doctoral student at McGill University in Montreal who co-authored both studies.
But, in a first, the burst was traced to an unprecedented 130,000 light-years from its associated galaxy's center, where few other stars exist.
'This is not only the first FRB to be found outside a dead galaxy, but compared to all other FRBs, it's also the farthest from the galaxy it's associated with," Shah said in a statement. "The location of this FRB so far outside its host galaxy raises questions as to how such energetic events can occur in regions where no new stars are forming.'
Further study of fast radio bursts needed, researchers say
Astronomers have pinpointed the origins of about 50 fast radio bursts to date, but some have suggested that around 1,000 more are waiting to be uncovered. Understanding and studying these radioactive blasts, scientists have posited, should help astronomers better understand the universe, and measure missing matter between galaxies.
Now that the latest research suggests fast radio bursts can originate from more environments than previously believed, the team is calling for more study.
'It's clear that there's still a lot of exciting discovery space when it comes to FRBs,' Eftekhari said in a statement, 'and that their environments could hold the key to unlocking their secrets.'
Both studies were published Jan. 21 in the Astrophysical Journal Letters.
Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [e-mail]