The newly discovered slow pulsar should not emit radio waves – but it does

Astronomers have added a new look to the neutron star zoo, showcasing a wide variety of compact magnetic remnants of dead, once massive stars.

The newly discovered highly magnetic pulsar has a surprisingly long period of rotation, which is a challenge for the theoretical understanding of these objects, the researchers said on May 30 in Natural astronomy. Called PSR J0901-4046, this pulsar transmits its beacon-like beam around the Earth every 76 seconds – three times slower than the previous recorder.

Although strange, some of the characteristics of this newly discovered pulsar are common among its relatives. This means that this object could help astronomers better connect the evolutionary phases between the mysterious species in the neutron star’s menagerie.

Astronomers know many types of neutron stars. Each of them is the compact object left after the explosive death of a massive star, but their characteristics may vary. The pulsar is a neutron star that astronomers discover at regular intervals thanks to its cosmic alignment: the star’s strong magnetic field produces radio waves radiating near the star’s poles, and each time one of these rays passes through Earth, astronomers can see radio pulse.

The newly discovered, slow pulsar is located in our galaxy, about 1,300 light-years away. Astrophysicists Manisha Caleb of the University of Sydney in Australia and her colleagues found it in data from the MeerKAT radio telescope outside Carnarvon, South Africa.

Further observations with MeerKAT revealed not only the slow, steady radio beating of the pulsar – a measure of how fast it rotates – but also another important detail: the speed at which rotation slows as the pulsar ages. And these two pieces of information revealed something strange about this pulsar. According to the theory, it should not emit radio waves. And yet it is so.

As neutron stars age, they lose energy and rotate more slowly. It is estimated that “at some point they have exhausted all their energy and stop emitting all kinds of emissions,” says Caleb. They died for the detectors.

The period of rotation of the pulsar and the deceleration of its rotation are related to the strength of its magnetic field, which accelerates the subatomic particles emanating from the star, and in turn generates radio waves. All neutron stars rotating as slowly as PSR J0901-4046 are located in this stellar “graveyard” and should not produce radio signals.

But “we just keep finding weirder and weirder pulsars that destroy that understanding,” said astrophysicist Maura McLaughlin of the University of West Virginia at Morgantown, who was not involved.

The newly discovered pulsar can be its own unique type of neutron star. But in some ways it seems a little familiar, Caleb says. She and her colleagues calculated the magnetic field of the pulsar from the speed of deceleration of its rotation and it is incredibly strong, similar to magnetars (SN: 17.09.02). This suggests that PSR J0901-4046 may be what is known as a “rest magnetar”, which is a pulsar with very strong magnetic fields, which sometimes emits brilliantly vigorous bursts of X-rays or other radiation. “We will need either X-rays or.” [ultraviolet] observations to confirm whether it is indeed a magnetar or a pulsar, “she says.

The detection team still has additional observations to analyze. “We have a lot more data on that,” said astrophysicist Ian Haywood of Oxford University. Researchers are looking at how the brightness of an object changes over time and whether its rotation changes abruptly or “bugs”.

Astronomers are also changing their automated computer programs, which scan radio data and mark intriguing signals to look for those longer periods of rotation – or even stranger and more mysterious neutron star phenomena. “The sweet thing about astronomy for me is what we’re waiting to find there,” says Haywood.

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