​Captured by cutting-edge radio telescope technology, a chance reactivation of a magnetar – the Universe’s most powerful magnets – has revealed an unexpectedly complex environment.

​Unlike the radio signals from other magnetars, this one is emitting enormous amounts of rapidly changing circular polarisation. Nothing like this has ever been seen before.

​The results suggest there is a superheated plasma above the magnetar’s magnetic pole, which is acting like a polarising filter. How exactly the plasma is doing this is still to be determined.

​The magnetar, XTE J1810-197, was first observed to emit radio signals in 2003, but then went silent for well over a decade. The University of Manchester’s 76-m Lovell telescope at the Jodrell Bank Observatory picked up new signals in 2018. This was quickly followed up by Murriyang, our Parkes radio telescope, which has been crucial to observing the magnetar’s radio emissions ever since.

​Murriyang is equipped with a cutting edge ultra-wide bandwidth receiver. The receiver allows for more improved measurements of celestial objects, especially magnetars, as it is highly sensitive to changes in brightness and polarisation across a broad range of radio frequencies.

​The research was published in Nature Astronomy.

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