Thirty-five years of timing of M53A with Arecibo and FAST

TL;DR

This paper presents a 35-year phase-coherent timing solution for pulsar M53A, combining archival Arecibo data with FAST observations, revealing its age, precise position, and a Helium white dwarf companion, and discusses pulsar origins in globular clusters.

Contribution

First long-term timing solution for M53A combining Arecibo and FAST data, identifying its companion, and analyzing its formation in globular clusters.

Findings

Pulsar age estimated between 0.70 and 0.85 Gyr.

Companion identified as a Helium white dwarf with 0.39 M☉.

System resembles wide pulsar-He WD binaries in the Galactic disk.

Abstract

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-year timing baseline; this combines the archival Arecibo Observatory data with the recent observations from the Five-hundred-meter Aperture Spherical radio Telescope (FAST). We find that the spin period derivative of the pulsar is between 6.1 and $7.5 \times 10^{-19} \rm \, s\, s^{-1}$, 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 $M_{\rm WD}=0.39^{+0.05}_{-0.07} \, \rm M_{\odot}$ and a cooling age of $0.14^{+0.04}_{-0.03}\, \rm Gyr$, confirming that the system formed recently in the history of the GC. 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.