Pulsar Timing and the Detection of Black Hole Binary Systems in Globular Clusters

Abstract

The possible existence of intermediate-mass binary black holes (IMBBHs) in globular clusters (GCs) offers us a unique geometry in which to detect spacetime oscillations. For certain pulsar-IMBBH configurations possible within a GC, the usual far-field plane wave approximation for the IMBBH metric perturbation severely under-estimates the induced pulse time-of-arrival (TOA) fluctuations. In this Letter, the expected TOA fluctuations induced by an IMBBH lying close to the line of sight between a pulsar and the Earth are calculated for the first time. For an IMBBH consisting of 10 and components, a 10 yr orbital period, and located 0.1 lt-yr from 3 10 M , the Earth-pulsar line of sight, the induced TOA fluctuations will be of order 5–500 ns.