Long-term observations of pulsars in the globular clusters 47 Tucanae and M15

TL;DR

This paper reports long-term pulsar observations in globular clusters 47 Tucanae and M15, revealing insights into cluster parameters and relativistic effects, including pulsar beam precession and future detectability predictions.

Contribution

It provides new measurements of pulsar spin derivatives and models relativistic precession, offering novel constraints on cluster properties and pulsar system geometry.

Findings

Measured higher-order spin derivatives constraining cluster parameters

Modeled relativistic spin precession in PSR B2127+11C

Predicted pulsar beam disappearance and reappearance timelines

Abstract

Multi-decade observing campaigns of the globular clusters 47 Tucanae and M15 have led to an outstanding number of discoveries. Here, we report on the latest results of the long-term observations of the pulsars in these two clusters. For most of the pulsars in 47 Tucanae we have measured, among other things, their higher-order spin period derivatives, which have in turn provided stringent constraints on the physical parameters of the cluster, such as its distance and gravitational potential. For M15, we have studied the relativistic spin precession effect in PSR B2127+11C. We have used full-Stokes observations to model the precession effect, and to constrain the system geometry. We find that the visible beam of the pulsar is swiftly moving away from our line of sight and may very soon become undetectable. On the other hand, we expect to see the opposite emission beam sometime between 2041 and 2053.