Gravitational-Wave Emission from Binary Black Holes Formed in Open Clusters

Understand

In order to investigate the formation rate of binary black holes (BBHs) in stellar clusters with a mass comparable to open clusters, we performed a series of direct $N$-body simulations of open clusters with a mass of $2.5\times10^3$ (Model A) and $10^4 M_{\odot}$ (Model B).

• Since such low-mass clusters would have been more populous than globular clusters when they were born, low-mass clusters are also candidates as the origin of BBHs which are the source of the gravitational waves.
• In model A, most of BBHs merged within 10 Gyr formed via dynamically formed main-sequence binary stars and stable and unstable mass transfer between them since open clusters collapse within the main-sequence life-time of massive stars.
• These binaries, therefore, have little eccentricities.