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Spin cycle

When trying to piece together exactly how magnetars produce fast radio bursts, scientists have a lot of variables to consider.
For example, magnetars (which are a type of neutron star) are so dense that a teaspoon of their material would weigh about a billion tons on Earth. Such a high density also means a strong gravitational pull: A marshmallow falling onto a typical neutron star would impact with the force of an early atomic bomb.
The strong gravity means the surface of a magnetar is a volatile place, regularly releasing bursts of X-rays and higher-energy light. Before the fast radio burst that occurred in 2022, the magnetar started releasing eruptions of X-rays and gamma rays (even more energetic wavelengths of light) that were observed 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 those X-ray bursts that happened before this glitch would have had, in principle, enough energy to create a fast radio burst, but they didn't," said study co-author Zorawar Wadiasingh, a research scientist at the University of Maryland, College Park and NASA's Goddard Space Flight Center. "So it seems like something changed during the slowdown period, creating the right set of conditions."
What else might have happened with SGR 1935+2154 to produce a fast radio burst? One factor might be that the exterior of a magnetar is solid, and the high density crushes the interior into a state called a superfluid. Occasionally, the two can get out of sync, like water sloshing around inside a spinning fishbowl. When this happens, the fluid can deliver energy to the crust. The paper authors think this is likely what caused both glitches that bookended the fast radio burst.
If the initial glitch caused a crack in the magnetar's surface, it might have released material from the star's interior into space like a volcanic eruption. Losing mass causes spinning objects to slow down, so the researchers think this could explain the magnetar's rapid deceleration.
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) might lead to the production of a fast radio burst. Some might not be connected to the burst at all.
"We've unquestionably observed something important for our understanding of fast radio bursts," said George Younes, a researcher at Goddard and a member of the NICER science team specializing in magnetars. "But I think we still need a lot more data to complete the mystery.