The solution to the strange flicker problem came when the Liverpool Gravitational Wave Optical Transient Observer Collaboration detected an object designated SN 2024afav on December 12, 2024. Initially, the object looked like a standard superluminous supernova. “It was just as bright and had bumps in the light curve as many other objects of this type,” says Farah. But as the telescopes continued watching, it started doing something unprecedented: It started chirping.
chirping star
In physics, chirp refers to a signal whose frequency increases continuously over time. In the case of SN 2024AFAV, its emissions were going up and down, but the gap between these jumps was decreasing. After the second and third bulges saw the gap between the two shrink by about 35 percent, Farah and his team realized they could calculate how much the gap would shrink between the next bulges.
The team adjusted their observing schedule, pointed their instruments at SN 2024afav, and found that the fourth bulge appeared exactly when they expected it. The fifth bulge enabled scientists to limit the reduction in duration to about 29 percent.
The fact that Farah and his colleagues could accurately predict the bumps was a huge blow to our existing magnetar models. While some of the irregular bumps can be explained by supernova ejecta colliding with gas clouds, it does not explain the perfectly timed, neat sinusoidal modulation with a constant decaying period. Random space debris doesn’t work that way.
“So, we came up with new models to describe this behavior,” Farah explains. He proposed a new physical mechanism that relied on the lens-Thirring effect, otherwise known as frame-dragging. Frame-dragging is a prediction of general relativity, where a massive rotating object slightly drags spacetime with itself as it rotates. “We had not tried this mechanism before because it had never been seen around a magnetar before,” says Farah. But when his team tried it, it turned out to be a perfect match for what was going on.
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