Discovery and Timing analysis of new pulsars in globular cluster NGC 5024: new observations from FAST

TL;DR

This paper reports the discovery of a new binary millisecond pulsar and provides detailed timing solutions for multiple pulsars in the distant globular cluster NGC 5024, utilizing FAST's high sensitivity to enhance pulsar detection and analysis.

Contribution

The study presents the first timing solutions for several pulsars in NGC 5024 and reports the discovery of a new binary millisecond pulsar, expanding knowledge of pulsar populations in distant globular clusters.

Findings

Discovery of a new binary millisecond pulsar PSR J1312+1810E.

Only isolated millisecond pulsar in NGC 5024, M53C.

Orbital periods and companion masses for multiple pulsars.

Abstract

NGC 5024 (M53) is the most distant globular cluster (GC) with known pulsars. In this study, we report the discovery of a new binary millisecond pulsar PSR J1312+1810E (M53E) and present the new timing solutions for M53B to M53E, 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 globular cluster, with a spin period of 12.53 ms and spin period derivative of $5.26 \times 10^{-20} \, \rm s \; s^{-1}$. Our results reveal the orbital periods of 47.7, 5.8, and 2.4 days for M53B, D, and E, respectively. The companions, with a mass of 0.25, 0.27, and 0.18 ${\rm M}_\odot$, respectively, are likely to be white dwarf stars; if they are extended objects, they don't 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.