Neutron stars: Mysterious object blasts out radio waves every 18 minutes

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Something extraordinarily bright in space is pulsing far slower than most similar cosmic objects, and it may be a strange type of neutron star that we have never seen before

Space



26 January 2022

A view of the Milky Way from the Murchison Widefield Array. The star icon shows the position of the mysterious pulsing object

Dr Natasha Hurley-Walker (ICRAR/Curtin) and the GLEAM Team

A mysterious object in space is pulsing in a way astronomers have never seen before. It may be a strange neutron star – the remnant of a massive star that has exploded. Examining celestial objects like it could help us understand the death throes of stars.

Natasha Hurley-Walker at Curtin University in Perth, Australia, and her colleagues found this object using the Murchison Widefield Array (MWA), a radio telescope in Australia. After spotting a barrage of radio waves that seemed to appear and then disappear, they dug into archival data taken by the MWA in early 2018 and found 71 more pulses.

With each pulse, the object – named GLEAM-X J162759.5-523504.3 and located about 4000 light years away – released huge amounts of energy. “The brightness here is really crazy – really, really, really extreme,” Hurley-Walker said in a press conference. “We did not expect to find anything so bright.”

It pulsed with a regular rhythm, brightening for 30 to 60 seconds once every 18.18 minutes. Nothing with a rhythm similar to this has been found before – most flashing radio objects in the sky pulse far faster, brightening and disappearing again in a matter of seconds. “No one really thought of looking for objects on this timescale because we couldn’t think of any mechanisms that produce them, and yet they exist,” said Hurley-Walker.

The pulsing indicates that the object is probably spinning, and other measurements of its light hint that it must have a powerful magnetic field. This led the researchers to suspect that it may be a magnetar, a type of neutron star with a particularly strong magnetic field, but it isn’t clear how a magnetar could rotate so slowly and shine so bright.

“I was concerned that it was aliens, but… it is across a very wide range of frequencies, and that means it must be a natural process – this is not an artificial signal,” said Hurley-Walker. She and her colleagues are now looking for more objects like this so we can figure out what they are.

Journal reference: Nature, DOI: 10.1038/s41586-021-04272-x

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