Eight new millisecond pulsars from the first MeerKAT globular cluster census

We have used the central 44 antennas of the new 64-dish MeerKAT radio telescope array to conduct a deep search for new pulsars in the core of nine globular clusters (GCs). This has led to the discovery of eight new millisecond pulsars in six different clusters. Two new binaries, 47 Tuc ac and 47 Tuc ad, are eclipsing 'spiders', featuring compact orbits (less than or similar to 0.32 d), very low mass companions, and regular occultations of their pulsed emission. The other three new binary pulsars (NGC 6624G, M62G, and Ter 5 an) are in wider (>0.7 d) orbits, with companions that are likely to be white dwarfs or neutron stars. NGC 6624G has a large eccentricity of e similar or equal to 0.38, which enabled us to detect the rate of advance of periastron. This suggests that the system is massive, with a total mass of M-tot = 2.65 +/- 0.07 M-circle dot. Likewise, for Ter 5 an, with e similar or equal to 0.0066, we obtain M-tot = 2.97 +/- 0.52 M-circle dot. The other three new discoveries (NGC 6522D, NGC 6624H, and NGC 6752F) are faint isolated pulsars. Finally, we have used the whole MeerKAT array and synthesized 288 beams, covering an area of similar to 2 arcmin in radius around the centre of NGC 6624. This has allowed us to localize many of the pulsars in the cluster, demonstrating the beamforming capabilities of the TRAPUM software backend and paving the way for the upcoming MeerKAT GC pulsar survey.

Automated summary

Using the central 44 antennas of the MeerKAT radio telescope array, a deep search for new pulsars in the core of nine globular clusters led to the discovery of eight new millisecond pulsars, including two compact orbit "spider" binaries and three wider orbit binary pulsars. This study demonstrates the capabilities of the MeerKAT array and paves the way for future GC pulsar surveys.