Astronomers witness magnetar birth for first time

[Celerity]

Scientists observed for more than 200 days the death of star that resulted in a dense, spinning remnant threaded with an extremely strong magnetic field

https://www.thetimes.com/uk/science/article/astronomers-magnetar-birth-first-2j8drllkw

https://archive.li/WoqHW


An artist’s impression of a magnetar
REUTERS

Astronomers have for the first time witnessed the birth of one of the universe’s most extreme objects: a magnetar packing the mass of about 500,000 Earths into a sphere barely 12 miles across. The discovery has provided the clearest evidence yet that these bizarre objects power some of the brightest explosions in the universe, while also showing how they literally twist the fabric of space-time, in accordance with Einstein’s general theory of relativity. When a large star reaches the end of its life, its core collapses under its own gravity. The outer layers explode outward in a supernova while the centre is crushed into an ultra-dense remnant, where a single teaspoon of material would weigh many billions of tons.

Occasionally, that remnant is born spinning extraordinarily fast and threaded with a magnetic field trillions of times stronger than Earth’s. Astronomers call such an object a magnetar. The study published in Nature observed for more than 200 days a superluminous supernova called SN 2024afav, a stellar blast discovered in December 2024 about a billion light-years away that shines at least ten times brighter than an ordinary supernova. Normally, the light from a supernova fades smoothly after reaching peak brightness. But after its peak, the light from SN 2024afav flickered as it faded, producing a series of small brightening pulses.


Albert Einstein, second from left, with fellow physicists Walther Mayer and Edwin Hubble at Mount Wilson Observatory
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Researchers believe this was due to some debris not escaping into space but forming a swirling disc of gas after falling back into the magnetar. The strange oscillations in radiation showed that the debris’ axis of rotation was tilted. According to Einstein’s theory of relativity, this would be due to a massive spinning object dragging the fabric of space-time around with it. It backed the idea that a magnetar is spinning within the expanding debris of the explosion and pouring in energy. “This is definitive evidence for a magnetar forming as the result of a superluminous supernova core collapse,” said Alex Filippenko, a professor of astronomy at the University of California, Berkeley and co-author of the study.

Filippenko said: “To see a clear effect of Einstein’s general theory of relativity is always exciting, but seeing it for the first time in a supernova is especially rewarding.” The team say discoveries like this may soon become more common as new telescopes begin surveying the sky in finer detail. “This is the most exciting thing I have ever had the privilege to be a part of. This is the science I dreamed of as a kid,” said Joseph Farah of UC Santa Barbara. “It’s the universe telling us out loud and in our face that we don’t fully understand it yet, and challenging us to explain it.”

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