Can the known millisecond pulsars help in the detection of intermediate-mass black holes at the centers of globular clusters?

Abstract

We consider the possibility of detecting intermediate-mass (103–104M⊙) black holes, whose existence at the centers of globular clusters is expected from optical and infrared observations, using precise pulse arrival timing for the millisecond pulsars in globular clusters known to date. For some of these pulsars closest to the cluster centers, we have calculated the expected delay times of pulses as they pass in the gravitational field of the central black hole. The detection of such a time delay by currently available instruments for the known pulsars is shown to be impossible at a black hole mass of 103M⊙ and very problematic at a black hole mass of 104M⊙. In addition, the signal delay will have a negligible effect on the pulsar periods and their first derivatives compared to the current accuracy of their measurements.