Collisional Hardening of Compact Binaries in Globular Clusters

Abstract

We consider essential mechanisms for orbit-shrinkage or "hardening" of compact binaries in globular clusters to the point of Roche-lobe contact and X-ray emission phase, focussing on the process of collisional hardening due to encounters between binaries and single stars in the cluster core. The interplay between this kind of hardening and that due to emission of gravitational radiation produces a characteristic scaling of the orbit-shrinkage time with the single-star binary encounter rate $\gamma$ in the cluster which we introduce, clarify, and explore. We investigate possible effects of this scaling on populations of X-ray binaries in globular clusters within the framework of a simple "toy" scheme for describing the evolution of pre-X-ray binaries in globular clusters. We find the expected qualitative trends sufficiently supported by data on X-ray binaries in galactic globular clusters to encourage us toward a more quantitative study.

8 pages, 4 figures. Accepted for publication in MNRAS

Cited by in corpus (6)

• Stellar-mass black holes in young massive and open stellar clusters and their role in gravitational-wave generation
• Stellar-mass black holes in young massive and open stellar clusters and their role in gravitational-wave generation II
• Low-Mass X-ray Binaries and Globular Clusters in Centaurus A
• Multi-Epoch X-ray Imaging of Globular Cluster M62 with Chandra
• Evolution of Compact-Binary Populations in Globular Clusters: A Boltzmann Study. I. The Continuous Limit
• Evolution of Compact-Binary Populations in Globular Clusters: A Boltzmann Study II. Introducing Stochasticity