Eight new Millisecond Pulsars Discovered by the MeerKAT Radio telescope

Credit: NASA

An international group of astronomers had discovered 8 new rare millisecond pulsars located within dense clusters of stars surrounding the Milky Way. The findings are detailed in the Royal Astronomical Society Paper.

Millisecond pulsars are extremely compact neutron stars, the most compact stars known, they can spin up to 700 times per second. This is the first pulsar discovery using the MeerKAT antennas and from the collaboration of TRAPUM (TRAnseints and PUlsars with MeerKAT) and MeerTIME.

MeerKAT is the largest telescope in the southern hemisphere and is very sensitive, which lets the TRAPUM project discover numerous new pulsars and transient events, establishing the population of pulsars in the plane and center of the Galaxy.

Two of the MeerKAT radio antennas, Credit: SARAO

MeerKAT consists of 64 antennas, located in the Nothern Cape of South Africa, run by the SARAO (South African Radio Astronomy Observatory). The team used 44 central antennas of the MeerKAT telescope, to conduct a deep search for new pulsars. 

Millisecond pulsar is much rarer than slower spinning pulsars, and are also amongst the more extreme objects in the universe, they pack a lot of mass, with a mass of at least 1.4 times the mass of Sun, but with a diameter of only 24km, which makes them very compact, and they also spin at a rate of hundreds of rotations per second. We detect them by the 2 beams of radio waves they emit from their poles which are detected by the observer at every rotation, and because of its magnetic field, which is also spinning, they look like flashing stars.

The formation of these objects is highly enhanced in the star rich environments at the center of globular clusters, a collection of stars that are bound together by their gravity and orbit outside the edge of the galaxy, so the team focused on the nine globular clusters surrounding the Milky Way and were able to find eight millisecond pulsars within 6 of those clusters which also made it the biggest millisecond pulsar study so far.

Globular Cluster NGC 6624, and the new Pulsar PSR J1823-3021G marked as the red G dot.

Credit: A. Ridolfi et al./INAF/Hubble Space Telescope

5 of those pulsars orbit another star, and one of these, PSR J1823-3021G, is particularly interesting because of its highly elliptical orbit and massive companion, and this system is most likely the result of an exchange of partners, where the original partner was expelled and replaced by the new companion star, as said by Alessandro Ridolfi, a postdoctoral at INAF and MPIfR, and also the author of the paper. Tasha Gautam and, a doctoral researcher at MPIfR in Bonn and also the co-author of the paper explains that this particular pulsar could have a high mass, suspected to be 2 times more of the Sun, or it could also be the first confirmed system formed by a millisecond pulsar and a neutron star if confirmed it would be ideal for studying fundamental physics.

TRAPUM will further work and use all the 64 dishes, which will increase the sensitivity and broaden the search to many more globular clusters and will also survey their outer regions.

MeerKAT will be upgraded by expanding it with an additional 20 dishes, and with 84 dishes, MeerKAT will become "MeerKAT+", and will also be integrated into the first phase of the SKAO project, an international effort to build the world's largest radio telescope, with over a square kilometer of collection area, Square Kilometer Array (SKA) project's construction will begin in 2027. And the first scientific observation of MeerKAT+ could begin by 2023.