Timing of millisecond pulsars in NGC 6752 - II. Proper motions of the pulsars in the cluster outskirts

Abstract

Exploiting a five-year span of data, we present improved timing solutions for the five millisecond pulsars known in the globular cluster NGC 6752. They include proper motion determinations for the two outermost pulsars in the cluster, PSR J1910-5959A and PSR J1910-5959C. The values of the proper motions are in agreement with each other within current uncertainties, but do not match (at 4 sigma and 2 sigma level respectively) with the value of the proper motion of the entire globular cluster derived in the optical band. Implications of these results for the cluster membership of the two pulsars are investigated. Prospects for the detection of the Shapiro delay in the binary system J1910-5959A are also discussed.