Artistic print of the pulsar of the 76’s (in magenta) compared to other sources of faster rotation. Credit: Danielle Futselaar
An international team of astronomers has discovered a strange radio-transmitting neutron star, which rotates very slowly, completing one rotation every 76 seconds.
The research team says it is an unusual discovery, as it resides in the cemetery of neutron stars where they do not expect to see any radio broadcasts. The discovery was made using the MeerKAT radio telescope in South Africa and was published in the journal, Astronomy of nature on May 30, 2022. The study was led by members of the ERC-funded MeerTRAP (More Transients and Pulsars) group at the University of Manchester.
The source was initially found from a single flash, or powder, by the MeerTRAP instrument, while relying on image observations directed by a different computer, ThunderKAT. MeerTRAP and ThunderKAT worked together to find out where it came from. Combining the data from the two teams, it was possible to confirm the pulses and obtain an accurate position of the source, allowing detailed and more sensitive tracking observations.
Neutron stars are extremely dense remnants of a massive star’s supernova explosion. They can produce beams of radio waves that sweep the sky as the neutron star rotates, producing regular flashes like cosmic beacons. Scientists currently know about 3,000 of them in our own Milky Way galaxy. However, the new discovery is different from anything we’ve seen so far. The team believes it could belong to the theorized class of ultra-long-period magnets with extremely strong magnetic fields.
MeerKAT telescope from South Africa. Credit: South African Astronomical Radio Observatory (SARAO)
Dr Manisha Caleb, formerly of the University of Manchester and now at the University of Sydney, who led the research, said: “Surprisingly, we only detect radio broadcasts from this source for 0.5% of its This means that it is very fortuitous for the radio beam to intersect with the Earth, so there are likely to be many more of these sources spinning very slowly in the galaxy, which has important implications for how neutron stars are born and age.
“Most pulsar surveys do not look for such long periods, so we have no idea how many of these sources there might be. In this case, the source was bright enough to detect unique pulses with the ‘MeerTRAP instrument in MeerKAT “.
“Surprisingly, we only detect radio emissions from this source during 0.5% of its rotation period. many more of these slowly rotating sources in the galaxy, which has important implications for how neutron stars are born and age. “
– Dr. Manisha Caleb
The newly discovered neutron star is called PSR J0901-4046 and shows characteristics of pulsars, magnets (ultra long period) and even fast bursts of radio. While the radio energy produced suggests a pulsar origin, the pulses with chaotic subpole components and the polarization of the pulses are reminiscent of magnets.
While the rotation period of PSR J0901-4046 might be more consistent with a white dwarf, another less extreme type of stellar remnant, scientists see no support for multiple wavelengths for this. It is currently unclear how long this source has been broadcasting on the radio. It was discovered in a well-studied part of the galaxy, but radio surveys do not usually look for such long periods or pulses lasting more than tens of milliseconds.
Dr. Manisha Caleb. Credit: University of Sydney
“The radio broadcast of this neutron star is different from anything we’ve ever seen before,” said Professor Ben Stappers of the University of Manchester and lead researcher on the MeerTRAP project. “We can see it for about 300 milliseconds, which is much longer than for most other radio-emitting neutron stars. There appear to be at least 7 different types of pulses, some of which show a strong structure. “These pulses could be giving us a vital insight into the nature of the emission mechanism of these sources.”
“The sensitivity that MeerKAT provides, combined with the sophisticated research that was possible with MeerTRAP and the ability to take simultaneous images of the sky made this discovery possible. Even then he needed an eagle’s eye to recognize it for something. which was possibly a real source because it looked so unusual! ”said Dr Ian Heywood of the ThunderKAT team and the University of Oxford who collaborated on this study.
Detecting similar sources is an observational challenge, implying that there may be a larger population undetected waiting to be discovered. This new discovery adds to the possibility of the existence of a new class of radio transients, ultra-long-period neutron stars, which suggests a possible connection with the evolution of highly magnetized neutron stars, magnetars. ultra long period and fast radio bursts.
Reference: “Discovery of a radio-emitting neutron star with an ultra-long spin period of 76 s” by Manisha Caleb, Ian Heywood, Kaustubh Rajwade, Mateusz Malenta, Benjamin Willem Stappers, Ewan Barr, Weiwei Chen, Vincent Morello, Sotiris Sanidas , Jakob van den Eijnden, Michael Kramer, David Buckley, Jaco Brink, Sara Elisa Motta, Patrick Woudt, Patrick Weltevrede, Fabian Jankowski, Mayuresh Surnis, Sarah Buchner, Mechiel Christiaan Bezuidenhout, Laura Nicole Driessen and Rob Fender, May 30, 2022 , Nature Astronomy.DOI: 10.1038 / s41550-022-01688-x