Abstract
Observations have shown that the majority of massive stars, the progenitors of black holes (BHs), have on average more than one stellar companion. In triple systems, wide inner binaries can be driven to a merger by a third body due to long-term secular interactions, most notably by the eccentric Lidov-Kozai effect. In this study, we explore the properties of BH mergers in triple systems and compare their population properties to those of binaries produced in isolation and assembled in dense star clusters. Using the same stellar physics and identical assumptions for the initial populations of binaries and triples, we show that stellar triples yield a significantly flatter mass ratio distribution from q = 1 down to q ∼0.3 than either binary stars or dense stellar clusters, similar to the population properties inferred from the most recent catalog of gravitational-wave events, though we do not claim that all the observed events can be accounted for with triples. While hierarchical mergers in clusters can also produce asymmetric mass ratios, the unique spins of such mergers can be used to distinguish them from those produced from stellar triples. All three channels occupy distinct regions in the total mass-mass ratio space, which may allow them to be disentangled as more BH mergers are detected by LIGO, Virgo, and KAGRA.
| Original language | English (US) |
|---|---|
| Article number | 78 |
| Journal | Astrophysical Journal |
| Volume | 937 |
| Issue number | 2 |
| DOIs | |
| State | Published - Oct 1 2022 |
Funding
We thank Kyle Kremer, Scott Coughlin, Michael Zevin, Max Moe, and Rosanne Di Stefano for useful discussions and suggestions. We thank Kyle Kremer for providing the cluster models used in this work. C.R. acknowledges support from NSF grant AST-2009916 at Carnegie Mellon University and a New Investigator Research grant from the Charles E. Kaufman Foundation. G.F. acknowledges support from NASA grant 80NSSC21K1722. Computations were supported in part through the resources and staff contributions provided for the Quest high-performance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. This work also used computing resources at the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) funded by NSF grant PHY-1726951 and computing resources provided by CIERA.
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science