By 2025 January, 60 pulsars were discovered by the Five-hundred-meter Aperture Spherical radio Telescope globular cluster (GC) pulsar survey (GC FANS), with spin periods spanning 1.98–3960.72 ms. Of these, 55 are millisecond pulsars (MSPs; P < 30 ms), while 35 are binaries with orbital periods spanning 0.12–466.47 days. This paper describes GC FANS, a deep, thorough search for pulsars in 41 GCs in the FAST sky (−14° < δ < 65°), and describes new discoveries in 14 of them. We present updated timing solutions for M92A, NGC 6712A, M71A, and M71E, all of which are “spider” pulsars with short orbital periods. We present new timing solutions for M71B, C, and D. With orbital periods of ∼466 and 378 days, M71B and M71C are the widest known GC binaries; these systems resemble the normal wide MSP-He WD systems in the Galactic disk. With a spin period of 101 ms, M71D is in an eccentric (e ∼ 0.63) orbit with an 11 day period and a massive companion; the system has a total mass of 2.63 ± 0.08 M _⊙. These features and its large characteristic age suggest it is a double neutron star system (DNS) formed via massive binary evolution early in the cluster’s history, akin to Galactic disk DNSs—unlike other candidate GC DNSs, which typically form dynamically. A comparative analysis of GC pulsar populations within FAST’s sky reveals that most clusters (10 of 14) resemble the Galactic disk MSP population, likely due to lower stellar densities.

The most distant globular cluster (GC) with known pulsars is NGC 5024 (M53). In this paper, we report the discovery of a new binary millisecond pulsar, PSR J1312+1810E (M53E), and present the new timing solutions for M53B–E based on 22 observations from the Five-hundred-meter Aperture Spherical radio Telescope (FAST). These discoveries and timing work benefit from FAST’s high sensitivity. We find that M53C is the only isolated millisecond pulsar known in this distant GC, with a spin period of 12.53 ms and spin period derivative of 5.26 × 10⁻²⁰ s s⁻¹. Our results reveal orbital periods of 47.7, 5.8, and 2.4 days for M53B, D, and E, respectively. The companions, with masses of 0.25, 0.27, and 0.18 M _⊙, respectively, are likely to be white dwarf stars; if they are extended objects, they do not eclipse the pulsars. We find no X-ray counterparts for these millisecond pulsars in archival Chandra images in the band of 0.3–8 keV. The characteristics of this pulsar population are similar to the population of millisecond pulsars in the Galactic disk, as expected from the low stellar density of M53.

PSR B1310+18A is a 33 ms binary pulsar in a 256 day, low eccentricity orbit with a low-mass companion located in NGC 5024 (M53). In this Letter, we present the first phase-coherent timing solution for this pulsar (designated as M53A) derived from a 35 yr timing baseline; this combines the archival Arecibo Observatory data with the recent observations from the Five-hundred-meter Aperture Spherical radio Telescope. We find that the spin period derivative of the pulsar is between 6.1 and 7.5 × 10⁻¹⁹ s s⁻¹, which implies a characteristic age between 0.70 and 0.85 Gyr. The timing solution also includes a precise position and proper motion for the pulsar, enabling the identification of the companion of M53A in Hubble Space Telescope data as a helium white dwarf (He WD) with a mass of M WD = 0.3 9 − 0.07 + 0.05 M ⊙ and a cooling age of 0.1 4 − 0.03 + 0.04 Gyr , confirming that the system formed recently in the history of the globular cluster. The system resembles, in its spin and orbital characteristics, similarly wide pulsar–He WD systems in the Galactic disk. We conclude by discussing the origin of slow pulsars in globular clusters, showing that none of the slow pulsars in low-density globular clusters are as young as the systems observed in the densest known globular clusters.

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the largest single-dish radio telescope in the world, and is now being commissioned after the first light in September 2016. Very long baseline interferometry (VLBI) is among the key science topics according to the original design. The FAST VLBI system has been established, and the first VLBI fringe has been successfully obtained. FAST will significantly improve the sensitivity of the existing VLBI networks in the future, and some science projects in need of high sensitivity will benefit from its participation.

Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics