A Puzzling Radio Signal Took 200 Million Years To Reach Earth, And Now We Can Confirm It Came From A Neutron Star
In 2022, a mysterious radio signal from space was detected and has now been confirmed to originate in the magnetic field of a neutron star 200 million light-years away.
These brief stellar blasts are known as fast radio bursts (FRBs). They are flashes of radio light that last just a fraction of a second, making them notoriously difficult to study. Sometimes, they carry enough energy to outshine entire galaxies.
The first FRB was spotted in 2007. Since then, astronomers have detected thousands of FRBs. However, it has always been unclear how the flares are launched into space. For years, astronomers have only been able to observe them by chance and simply guess at their origins.
But thanks to wide-field radio telescopes, experts now have a better understanding of their cause. It appears that FRBs originate from highly magnetic neutron stars called magnetars. A team of astronomers used a method known as scintillation to learn more about the phenomenon.
In a new study, the team focused on FRB 20221022A to search for answers. When it was detected in 2022, the light signal lasted for approximately two milliseconds.
Researchers from the Massachusetts Institute of Technology analyzed the FRB’s scintillation and were able to determine the size and location of its light source.
A scintillation effect occurs when light from a small bright source, like a neutron star, passes through the atmosphere.
The light bends in a way that makes the star look like it is twinkling. The smaller and farther away a stellar object is, the more it seems to flicker.
The team found that the FRB most likely came from a neutron star’s magnetosphere, just about 10,000 kilometers from the surface of the neutron star, which is less than the distance between New York and Singapore, according to the study authors.
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It was the first definitive proof that FRBs can arise from the magnetospheres of such ultra-dense stars. In the past, studies predicted that atoms would be torn apart around magnetars.
“There’s been a lot of debate about whether this bright radio emission could even escape from that extreme plasma,” said Dr. Kenzie Nimmo, the lead author of the study.
“The exciting thing here is, we find that the energy stored in those magnetic fields, close to the source, is twisting and reconfiguring such that it can be released as radio waves that we can see halfway across the universe.”
Overall, the findings confirm that magnetars are the source of FRBs. FRBs are specifically the result of the stars’ intense magnetic fields. Further research is needed to figure out how these magnetic fields can generate intense radio light so quickly.
The details of the study were published in the journal Nature.
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