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Using two of the agency’s X-ray telescopes, researchers picked up the erratic behavior of a dead star as it emitted a bright, brief burst. Burst of radio waves.
In an injection that slows its rotation, this artist’s visualization shows a magnet losing material to space. The magnet’s strong, twisted magnetic field lines (shown in green) can affect the flow of electrically charged material from the object, which is a type of neutron star. Image credit: NASA/JPL-Caltech
What is the cause of the mysterious eruption? Radio waves from deep space? Astronomers may be one step closer to providing an answer to this question. Two NASA X-ray telescopes recently observed one such event – called a fast radio burst – minutes before and after it occurred. This unprecedented sight puts scientists on the path to better understanding these extreme radio events.
While they only last for a fraction of a second, fast radio bursts can release almost as much energy as the Sun does in a year. Their light also creates a laser-like beam, distinguishing them from more chaotic cosmic explosions.
Because bursts are so short, they are often difficult to spot. Before 2020, those whose origins were traced to exits outside our own galaxy – too far for astronomers to see what made them. Then oh High-speed radio bursts in Earth’s home galaxy.starts with an extremely dense material called a magnetar – the collapsed remnants of an exploding star.
In October 2022, the same magnetar – known as SGR 1935+2154 – produced another fast radio burst, which NASA studied in detail. good (Neutron Star Interior Composition Explorer) on the International Space Station and Nostar (Nuclear Spectroscopic Telescope Array) in low Earth orbit. Before and after the fast radio burst, the telescopes observed the magnet for hours, getting a glimpse of what happened on the surface of the source object and in its immediate environment. The results, described in a. A new study This is an example of what NASA’s telescopes can do, published in the journal Nature. Do the work of the mill To observe and follow short-lived events in the universe.
The burst occurred between two “disruptions” when the magnetor suddenly began spinning rapidly. SGR 1935+2154 is estimated to be about 12 miles (20 km) across and rotates about 3.2 times per second, meaning its surface was moving at about 7,000 miles per hour (11,000 km/h). It would take a lot of energy to slow it down or speed it up. That’s why the study’s authors were surprised to find that between failures, the magnetar slowed to its pre-failure speed in just nine hours, or about 100 times faster than observed in Magnetar. Is.
“Usually, when disturbances occur, it takes several weeks or months for it to return to its normal speed,” said Chen Ping-ho, an astrophysicist at Taiwan’s National Changhua University of Education and lead author of the new study. ” “So clearly things are happening with these objects on a much shorter time scale than we previously thought, and that may have to do with how fast the radio burst is generated.”
Scientists have been trying to piece together what happens when magnetars produce rapid radio bursts. Many variables to consider.
For example, magnets (which are a type of Neutron star) are so dense that a spoonful of their contents would weigh. About a billion tons on Earth. Such high density also means a strong gravitational force: a marshmallow falling on a typical neutron star would be affected by the force of a primordial atomic bomb.
Strong gravity means that the surface of the magnet is an unstable place, Continued regularly X-rays and bursts of high-energy light. Before the fast radio burst in 2022, the magnetar began emitting X-rays and gamma rays (even more energetic wavelengths of light) that were seen in the peripheral vision of high-energy space telescopes. This increase in activity prompted mission operators to point NICER and NuSTAR directly at the magnetar.
“All of the X-ray bursts that preceded this breakdown would, in theory, have had enough energy to produce a fast radio burst, but they didn’t,” said study co-author Zoravar Wadiasingh, of the University of A research scientist. Maryland, College Park and NASA’s Goddard Space Flight Center. “So something seems to have changed during the slowdown period, creating the right set of conditions.”
What else would have happened to SGR 1935+2154 to produce a fast radio burst? One factor may be that the outside of the magnet is solid, and the high density compresses the interior into a state called superfluid. Occasionally, the two may be out of sync, like water swirling inside a spinning fishbowl. When this happens, the fluid can provide energy to the crust. The paper’s authors believe it is likely due to both anomalies that bookended the fast radio burst.
If the initial perturbation caused a crack in the surface of the magnetar, it may have released material from the star’s interior into space, similar to a volcanic eruption. Losing mass slows down spinning objects, so the researchers believe this could explain the magnet’s rapid decline.
But having observed only one of these events in real time, the team still can’t say for sure which of these factors (or others, such as the magnetar’s powerful magnetic field) produced the fast radio burst. can cause Some may not be associated with a burst at all.
“We’ve made an observation that is undoubtedly important to our understanding of fast radio bursts,” said George Younes, a Goddard researcher and member of the NICER science team specializing in magnetars. “But I think we still need a lot more data to complete the mystery.”
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