Another indication of the true nature of fast radio bursts

Artist’s concept of a magnet. Credit: NASA/JPL-Caltech

Fast radio bursts (FRBs) are strange events. They can only last for milliseconds, but can leave the galaxy behind in that time. Some FRBs are repeaters, meaning they can occur more than once from the same location, while others occur only once. We’re still not entirely sure what causes them, or even if the two types have the same cause. But thanks to the support of observations from ground-based radio telescopes and space-based X-ray observatories, we are starting to detect FRBs.

Most FRBs occur far beyond our galaxy, so while we can pin down their locations, it’s hard to observe any details about their cause. Then, in 2020, we observed a fast radio burst in our galaxy. Later observations showed that it originated in the region of a highly magnetic neutron star .

This led to the idea that magnetars are the source of FRBs, possibly through magnetic flares similar to solar flares. But stars like Magneto and the Sun are very different. It was not yet clear how a magnet could release such a large amount of energy so quickly, even with their intense magnetic fields. Now a new study suggests that the rotation of the magnet plays an important role.

the studyappears on the preprint server. arXiv, 2020 FRB focuses on magnetars. Known as SGR 1935+2154, it is both a magnetar and a pulsar. This means it emits a regular radio pop as it spins.

Pulsars are incredibly regular and are used as a kind of cosmic clock for everything from studying. For hypothetical navigation through the galaxy. But over time the pulsar’s rotation slows down as the rotational energy is drained out by its magnetic field. By looking at this decay rate, astronomers can better understand the composition of neutron stars and magnetars.

Another indication of the true nature of fast radio bursts

How two magnetic anomalies are associated with fast radio bursts. Credit: Hu, Chen Ping, et al

But sometimes the rate of rotation changes suddenly. It is known as a If the rotation suddenly speeds up, and an opposite error if it suddenly slows down. These disturbances occur when a neutron star undergoes some kind of sudden structural change, such as a star earthquake.

In 2022, NASA’s Nuclear Spectroscopic Telescope Array (NUSTAR) spacecraft and the Neutron Star Interior Composition Explorer (NICER) Both observed another fast radio burst from SGR 1935+2154. Together they had X-ray data on the magnetar before, during and after the explosion. The team watched again During that time and I found a dip Rotation rate during eruption This means the relationship between rotation and eruption.

What the team saw overall was a flurry of X-ray emission from SGR 1935+2154 shortly before the explosion, then a breakdown in rotation, the explosion itself, and a return to the regular rotation rate. This is just an observation, but it seems that the magnetic energy in the magnet was ready to release before the explosion, and the change in rotation created the conditions necessary to produce an FRB.

More information:
Chen Ping Hu et al., Rapid spin changes around magnetofast radio bursts, arXiv (2024). DOI: 10.48550/arxiv.2402.09291

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Reference: Another clue to the true nature of fast radio bursts (2024, February 16) Retrieved February 17, 2024 from https://phys.org/news/2024-02-clue-true-nature-fast-radio.html

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