Strange Signal Coming From Dead Galaxy, Scientists Say

Yahoo

26-01-2025

Astronomers say they've detected a mysterious type of signal known as a fast radio burst coming from an ancient, dead galaxy billions of light years away. Figuratively speaking, it makes for one hell of a sign of life.
The findings, documented in two studies published in The Astrophysical Journal Letters, upends the long held belief that FRBs — extremely powerful pulses of energy — originate exclusively from star-forming regions of space, as dead galaxies no longer support the birth of new stars.
Adding to the seeming improbability of the FRB's origin, the researchers believe that the signal's source came from the furthermost outskirts of the galaxy, about 130,000 light years from its center, with only moribund stars at the end of their stellar evolution for company.
"This is both surprising and exciting, as FRBs are expected to originate inside galaxies, often in star-forming regions," said Vishwangi Shah, lead author of one of the studies and an astronomer at McGill University, said in a statement about the work. "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."
Though they're often only milliseconds in duration, FRBs are so powerful at their source that a single pulse emits more energy than our Sun does in an entire year.
What could cause such staggering outbursts? Astronomers have speculated that they originate from magnetars, a type of collapsed, extremely dense stellar object called a neutron star that maintains an unfathomably potent magnetic field, perhaps trillions of times stronger than Earth's.
But that theory is now being challenged by this latest FRB, designed FRB 20240209A, because there are no young stars in the 11.3 billion year old galaxy that could form magnetars. Only extremely massive stars, which have short lifespans as a consequence of their size and thus would need to have been recently formed, possess enough mass to collapse into neutron stars in the first place.
FRB 20240209A isn't the first to be found in such a remote location. In 2022, astronomers detected another signal originating from the outskirts of its galaxy, Messier 81, where no active star formation was taking place.
"That event single-handedly halted the conventional train of thought and made us explore other progenitor scenarios for FRBs," said Wen-fai Fong, a coauthor of both studies and an astrophysicist at Northwestern University, in the statement. "Since then, no FRB had been seen like it, leading us to believe it was a one-off discovery — until now."
Crucially, the M81 FRB was found in a dense conglomeration of stars called a globular cluster. Given their similar circumstances, it led the astronomers to believe that FRB 20240209A could be residing in a globular cluster, too. To confirm this hunch, they hope to use the James Webb Telescope to image the region of space around the FRB's origins.
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