Discovery of a millisecond pulsar associated with Terzan 6

TL;DR

This paper reports the discovery of the first millisecond pulsar in the globular cluster Terzan 6 using high-frequency radio observations, highlighting the cluster's potential to host more pulsars despite previous non-detections.

Contribution

The discovery of PSR J1750-3116A in Terzan 6 at high radio frequencies is a novel finding, demonstrating the effectiveness of high-frequency searches in dense globular clusters.

Findings

First pulsar discovered in Terzan 6.

Pulsar has a 5.33 ms spin period.

High-frequency observations are effective for pulsar detection.

Abstract

Observations show that globular clusters might be among the best places to find millisecond pulsars. However, the globular cluster Terzan 6 seems to be an exception without any pulsar discovered, although its high stellar encounter rate suggests that it harbors dozens of them. We report the discovery of the first radio pulsar, PSR J1750-3116A, likely associated with Terzan 6 in a search of C-band (4-8 GHz) data from the Robert C. Byrd Green Bank Telescope with a spin period of 5.33 ms and dispersion measure, DM$\simeq$ 383 ${\rm pc\,cm^{-3}}$. The mean flux density of this pulsar is approximately 3 $\mu$Jy. The DM agrees well with predictions from the Galactic free electron density model, assuming a distance of 6.7 kpc for Terzan 6. PSR J1750-3116A is likely an isolated millisecond pulsar, potentially formed through dynamical interactions, considering the core-collapsed classification and the exceptionally high stellar encounter rate of Terzan 6. This is the highest radio frequency observation that has led to the discovery of a pulsar in a globular cluster to date. While L-band (1-2GHz) observations of this cluster are unlikely to yield significant returns due to propagation effects, we predict that further pulsar discoveries in Terzan 6 will be made by existing radio telescopes at higher frequencies.