Magnetars Drag Spacetime to Power Superluminous Supernovae

Arthur T Knackerbracket writes:

Frame-dragging may explain an odd pattern seen in the brightest supernovae:

Some of the most extreme explosions in the universe are Type I superluminous supernovae. "They are one of the brightest explosions in the Universe," says Joseph Farah, an astrophysicist at the University of California, Santa Barbara. For years, astrophysicists tried to understand what exactly makes superluminous supernovae so absurdly powerful. Now it seems like we may finally have some answers.

Farah and his colleagues have found that these events are most likely powered by magnetars, rapidly spinning neutron stars that warp the very space and time around them.

Magnetars have been a leading candidate for the engine behind superluminous supernovae. The theory says these insanely magnetized stars are born from the collapsing core of the original progenitor star and emit energy via magnetic dipole radiation. "This core is roughly a one solar mass object that gets crushed down to the size of a city," Farah explains. As its spin slows down, a magnetar bleeds its rotational energy into the expanding material of the dead star, lighting it up.

The problem was that this theory did not quite explain observations. In a standard magnetar model, the light curve of the supernova should rise rapidly and then fade away evenly as the neutron star loses its rotational energy. "This way the light curve, in the prediction of this model, just goes up and then down quite smoothly," Farah says. But when astronomers observe superluminous supernovae, they almost never see this smooth fade. Instead, they see bumps, wiggles, and strange modulations. The light curve flickers over months.

For a while, scientists tried to patch the magnetar engine theory to fit observations. Maybe the expanding debris was slamming into irregular shells of material shed by the star before it died. Or perhaps the magnetar engine was spitting out random, violent flares. But these explanations required highly specific, fine-tuned parameters to match what we were seeing through our telescopes.

The solution to the strange flickering 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 as bright and it had bumps in the light curve like many other objects of this kind," Farah says. But as the telescopes kept watching, it started doing something unprecedented: It started to chirp.

[...] The flickering in the superluminous supernovae, Farah hypothesized, was caused by the extreme gravity of a newborn magnetar dragging the very spacetime around it along as it was spinning.

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