Globular cluster

Physics

Stars

Cluster (spacecraft)

Political science

Gravitational wave

Eccentricity (behavior)

Programming language

Population

Binary black hole

Observable

Mathematics

Computer science

Astrophysics

Binary number

Quantum mechanics

Medicine

Arithmetic

Environmental health

Physical review. D/Physical review. D.

We derive the probability for a newly formed binary black hole (BBH) to undergo an eccentric gravitational wave (GW) merger during binary-single interactions inside a stellar cluster. By integrating over the hardening interactions such a BBH must undergo before ejection, we find that the observable rate of BBH mergers with eccentricity $>0.1$ at $10\ \rm{Hz}$ relative to the rate of circular mergers can be as high as $\sim 5\%$ for a typical globular cluster (GC). This further suggests that BBH mergers forming through GW captures in binary-single interactions, eccentric or not, are likely to constitute $\sim 10\%$ of the total BBH merger rate from GCs. Such GW capture mergers can only be probed with an $N$-body code that includes General Relativistic corrections, which explains why recent Newtonian cluster studies not have been able to resolve this population. Finally, we show that the relative rate of eccentric BBH mergers depends on the compactness of their host cluster, suggesting that an observed eccentricity distribution can be used to probe the origin of BBH mergers.

Eccentric black hole mergers forming in globular clusters