Astronomers Believe That Mysterious Radio Bursts Actually Come From Massive Galaxies

Thousands of flashes of cosmic energy, also known as fast radio bursts (FRBs), erupt across the sky every day. They were first discovered in 2007. Since then, scientists have been working to uncover their origins.
They can’t be seen by the human eye, and they don’t last very long, so scientists are lucky just to get the chance to observe FRBs.
But now, a team of astronomers has hypothesized that these light flashes typically occur in massive galaxies from powerful eruptions of rare stars that have been long dead. These stars are called magnetars. Their findings also suggest that magnetars are cosmic fusions of two stars.
“The immense power output of magnetars makes them some of the most fascinating and extreme objects in the universe,” said Kritti Sharma, the lead author of the study from the California Institute of Technology.
“Very little is known about what causes the formation of magnetars upon the death of massive stars. Our work helps to answer this question.”
The research team analyzed the home galaxies of 30 FRBs that were recorded by California’s Deep Synoptic Array-110, a project funded by the National Science Foundation. To date, the radio array has detected a total of 70 FRBs.
The researchers found that the bursts originated in huge star-forming galaxies that are rich in metals, which, in astronomical terms, refers to any element heavier than hydrogen and helium.
Metal-rich environments of this kind might be key to the formation of magnetars, the leading candidates for the production of FRBs.
Magnetars are a type of neutron star. Since magnetars originate in different kinds of environments, they may be the remains of stellar mergers instead of the result of massive stars collapsing and exploding.

ZHI – stock.adobe.com – illustrative purposes only
In such galaxies, stars abundant with metals that exist in pairs tend to become less compact as they evolve. They accelerate the transfer of mass between each other, triggering a stellar merger.
The star that survives is usually the larger of the two. It burns the fuel it received from its companion, creating magnetic fields that are hundreds of trillions of times stronger than Earth’s. The result is a magnetar.
“A star with more metal content puffs up, drives mass transfer, culminating in a merger, thus forming an even more massive star with a total magnetic field greater than what the individual star would have had,” Sharma said.
This scenario could also explain why FRBs are occasionally detected in regions with old stars. There are still many questions surrounding the nature of FRBs.
So far, astronomers have no idea what causes them to behave the way they do. Some seem to go off several times a day, while others only flash once. It is currently one of astronomy’s biggest mysteries.
In the future, the team hopes to search for more FRBs and pinpoint their places of origin using the radio array DSA-110.
The details of the study were published in the journal Nature.
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