A team of astronomers used South Africa’s MeerKAT radio telescope to discover eight-millisecond pulsars in dense clusters of stars known as “globular clusters.” A millisecond pulsar is a neutron star, one of the densest known stars, rotating up to 700 times per second. This is the first pulsar discovery using the MeerKAT antenna, which comes from the collaboration of two international cooperation organizations, TRAPUM and MeerTIME, and is detailed in the recently published Monthly Journal of the Royal Astronomical Society.
Millisecond pulsars are very compact stars, consisting mainly of neutrons, and are one of the most extreme objects in the universe: they hold hundreds of thousands of times the mass of Earth in a sphere about 24 kilometers in diameter; They emit a beam of radio waves that observers can detect every time they spin, like a lighthouse. The formation of these objects is highly reinforced in a star-rich environment at the center of globular clusters.
Professor Ben Stappers, of the University of Manchester and co-chief executive of the TRAPPUM project, said: “It’s really exciting to see the potential of using the excellent MeerKAT telescope to discover a large number of new millisecond pulsars in globular clusters. “It’s also a preview of what the Square Kilometer Array Telescope can achieve, and MeerKAT is one of its predecessors.
Study lead author Alessandro Ridolfi, a postdoctoral researcher at INAF and MPIfR, said: “We pointed the MeerKAT antenna to nine singular clusters, six of which we found new pulsars! Five of these new pulsars orbit another star, and one of them, PSR J1823-3021G, is particularly interesting. Ridolfi continued: “Due to its highly elliptical orbit and a huge companion star, the system may be the result of a partner exchange: after a ‘close encounter’: the original partner is evicted and replaced by a new companion star. ”
Tasha Gautam, the Ph.D. researcher at MPIfR in Bonn and co-author of the paper, explained: “This particular pulsar may have a very high mass, more than twice the mass of the sun, or it may be the first confirmed system formed by millisecond pulsars and neutron stars.” If confirmed by current additional observations, this would make the millisecond pulsar a powerful laboratory for basic physics. ”
The eight new pulsars are just the tip of the iceberg: the observations that led to their discovery used only about 40 of MeerKAT’s 64 antennas and focused only on the central region of the globular cluster.
The TRAPUM collaboration (TRAnsients and PUlsars using MeerKAT) is one of several large survey proposals (LSPs) approved to use the MeerKAT telescope. It is co-led by Professor Staples and Professor Kramer (MPIfR/UoM) of the University of Manchester. TRAPUM will use MeerKAT’s extreme sensitivity to search for pulsars in the sky. One of the places they will search is the globular cluster. The results were obtained in collaboration with MeerKAT’s other LSP, MeerTIME, and their infrastructure was used to capture data.
This work also provides a testing platform for trapped collaborations to better plan a comprehensive spherical cluster pulsar survey, which is underway using all 64 antennas currently available (thus further improving sensitivity). The survey will expand the search to more globular clusters and will also look at their outer regions.
