Timing a millisecond pulsar in a globular cluster

Certain evolutionary scenarios predict that millisecond pulsars should form in the cores of globular clusters; such a source may be present in M28. Gravitational perturbations of the cluster stars should subject the pulsar to a time-varying acceleration. This may be detectable in the arrival time analysis as an anomalous $$\ddot{P}$$, much larger than that expected from magnetic dipole braking. This effect can be used as a probe of the cluster dynamics and will degrade the usefulness of such pulsars in searches for long-wavelength cosmological gravitational radiation.