Eight new millisecond pulsars from the first MeerKAT globular cluster census

Abstract

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. 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 (≲ 0.32 days), 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 days) orbits, with companions that are likely to be white dwarfs or neutron stars. NGC 6624G has a large eccentricity of e ≃ 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 Mtot = 2.65 ± 0.07 M⊙. Likewise, for Ter 5 an, with e ≃ 0.0066, we obtain Mtot = 2.97 ± 0.52 M⊙. 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 ∼2 arcmin in radius around the center 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 globular cluster pulsar survey.

Two New Black Widow Millisecond Pulsars In M28

“…The initial MeerKAT data that we used to search for new pulsars in M28 was part of the series of survey observations using the core MeerKAT antennas (∼42 out of 64 dishes) that targeted globular clusters containing known pulsars (Ridolfi et al 2021). These observations were made as part of a joint effort between the Meer-Time project (Bailes et al 2020), which conducts longterm pulsar timing, and the TRAPUM project (TRansients And PUlsars with MeerKAT; Stappers & Kramer 2016) 4 , whose goal is to discover new radio pulsars in targeted regions that have yielded significant discoveries in the past as well as environments that are conducive for pulsar formation.…”

“…Due to the high likelihood of finding MSPs within GCs, and especially those in exotic orbits, GCs have been the focus of many pul-sar searches using the largest radio telescopes and over 232 have been found so far 2 . There are 39 pulsars currently known in Terzan 5 (Lyne et al 1990(Lyne et al , 2000Ransom et al 2005;Hessels et al 2006;Andersen & Ransom 2018;Cadelano et al 2018;Ridolfi et al 2021) and 27 in 47 Tucanae (Camilo et al 2000;Manchester et al 1991;Robinson et al 1995;Pan et al 2016;Ridolfi et al 2021). M28 had, up until this work, 12 known pulsars (Bégin 2006), ranking it as the third cluster in number of known pulsars.…”

“…Two pulsar-based large science projects, MeerTime and TRAPUM, working together as described below, have made observations of several globular clusters. Initial results from a globular cluster survey targeting clusters with known pulsars, for the purposes of comparing older detections with MeerKAT ones, has been presented by Ridolfi et al (2021). With 15 years since the last dedi-cated searches (using the GBT), the high sensitivity of MeerKAT coupled with better computing power and the availability of higher-dimension acceleration or "jerk" searches (e.g.…”

Design, implementation, and qualification of high-performance time and frequency reference for the MeerKAT telescope

“…7, and then there is a discussion and conclusion on what was achieved in Sec. 8. This discussion has a larger emphasis on the timing accuracy verification, which is the newer result in part (c), and therefore much detail on that is shown explicitly in Sec.…”

“…5 An important design goal, which is to perform time domain science, has been largely achieved due to the relatively compact core and recent promising observations. [6][7][8] Some pulsars' stability of the order of 4 ns • h −1 is now projected based on MeerKAT measurements. 9 This is an improvement of prior best state-of-the-art measurements on the Parkes Pulsar Timing Array in 2014.…”