Magnetars are neutron stars with strong magnetic fields. Along with CSIRO astronomers, Dr Manisha Caleb from the School of Physics discovered one of the most powerful magnets discovered – XTE J1810-197 – and it doesn’t quite fit existing theory.
Magnetar – illustrative photo. Image credit: Pixabay (Free Pixabay license)
Astronomers using Murriyang, the CSIRO radio telescope at Parkes NSW, have detected unusual radio pulses coming from a previously dormant star with a powerful magnetic field.
New results published today in Natural Astronomy describe radio signals from the XTE J1810-197 magnetar behaving in complex ways.
Magnetars are a type of neutron star and the most powerful magnets in the Universe. Located about 8,000 light years away, this magnetar is also the closest known to Earth.
Most magnetars are known to emit polarized light, although the light emitted by this magnetar is circularly polarized, where the light appears to form a spiral as it travels through space.
Dr Marcus Lower, a postdoctoral researcher at Australia’s national science agency CSIRO, led the research and said the results were unexpected and completely unprecedented.
“Unlike the radio signals we have observed from other magnetars, this one emits huge amounts of rapidly changing circular polarization. We’ve never seen anything like this before,” Dr. Lower said.
Co-author Dr Manisha Caleb from the School of Physics and Institute of Astronomy at the University of Sydney, said the study of magnetars offers insight into the physics of intense magnetic fields and the environments they create .
“The signals emitted by this magnetar imply that the interactions on the star’s surface are more complex than previous theoretical explanations,” she said.
The detection of radio pulses from magnetars is already extremely rare: XTE J1810-197 is one of the few known to produce them.
Although it’s unclear exactly why this magnetar behaves so differently, the team has an idea.
“Our results suggest that there is superheated plasma above the magnetic pole of the magnetar, which acts as a polarizing filter,” Dr Lower said.
“Exactly how plasma does this remains to be determined. »
XTE J1810-197 was first observed emitting radio signals in 2003. It then remained silent for more than a decade. The signals were again detected by the University of Manchester’s 76 meter Lovell Telescope at Jodrell Bank Observatory in 2018 and quickly followed by Murriyang at Parkes, which has since played a crucial role in observing the radio broadcasts from the magnetar.
The 64 meter diameter telescope located in Wiradjuri country is equipped with a state-of-the-art ultra-wideband receiver. The receiver was designed by CSIRO engineers, world leaders in developing technology for radio astronomy applications.
The receiver allows more precise measurements of celestial objects, particularly magnetars, because it is very sensitive to changes in brightness and polarization over a wide range of radio frequencies.
Magnetar studies such as these provide insight into a range of extreme and unusual phenomena, such as plasma dynamics, X-ray and gamma-ray bursts, and potentially fast radio bursts.
Research
Lower, M, et al, ‘Linear to circular conversion in polarized radio emission from a magnetar’, Natural Astronomy, volume 8 (2024). DOI: 10.1038/s41550-024-02225-8
Reconnaissance
Researchers recognize the Wiradjuri people as the traditional custodians of the Parkes Observatory site where Murriyang, the CSIRO’s Parkes radio telescope, is located.
Statement
The authors declare no competing interests. The research was funded by the Australian Research Council, the National Natural Science Foundation of China and the Netherlands Research Council.
Source: University of Sydney
Originally published in The European Times.
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