Detecting Intermediate-mass Black Holes Using Miniature Pulsar Timing Arrays in Globular Clusters

TL;DR

This paper proposes using miniature pulsar timing arrays in globular clusters to detect intermediate-mass black hole binaries through correlated pulsar timing residuals, potentially revealing elusive IMBHs.

Contribution

It introduces a novel method employing mini-PTAs with MSPs in GCs to detect IMBH binaries via their induced timing residuals, expanding observational capabilities.

Findings

IMBH binaries could induce microsecond-level timing residuals in MSPs.

Favorable configurations in clusters like ω Centauri and M15 could detect binaries with q>0.1.

Future high-precision timing could reach 100-nanosecond sensitivity, broadening detection prospects.

Abstract

Theoretical models predict that intermediate-mass black holes (IMBHs) exist in globular clusters (GCs), but observational evidence remains elusive. Millisecond pulsars (MSPs), which are abundant in GCs and have served as precise probes for gravitational waves (GWs), offer a unique opportunity to detect potential IMBH binaries in GCs. Here, we consider the possibility of using multiple MSPs in a GC to form a miniature pulsar timing array (PTA), so as to take advantage of their correlated timing residuals to search for potential IMBH binaries in the same cluster. Our semi-analytical calculations reveal that nearby IMBH binaries around MSPs in GCs could induce microsecond-level timing residuals. In GCs like $\omega$ Centauri and M15, favorable configurations are found which could lead to the detection of binaries with mass ratios $q\gtrsim0.1$ and orbital periods of a few days. We estimate that future higher-precision timing programs could achieve $100$-nanosecond sensitivity, substantially expanding the searchable parameter space and establishing mini-PTAs as powerful detectors of IMBHs.