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arXiv · 1706.02309

Spin-Orbit Misalignment of Merging Black-Hole Binaries with Tertiary Companions

Bin Liu·Dong Lai
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Abstract

We study the effect of external companion on the orbital and spin evolution of merging black-hole (BH) binaries. An sufficiently close by and inclined companion can excite Lidov-Kozai (LK) eccentricity oscillations in the binary, thereby shortening its merger time. During such LK-enhanced orbital decay, the spin axis of the BH generally exhibits chaotic evolution, leading to a wide range ($0^\circ$-$180^\circ$) of final spin-orbit misalignment angle from an initially aligned configuration. For systems that do not experience eccentricity excitation, only modest ($\lesssim 20^\circ$) spin-orbit misalignment can be produced, and we derive an analytic expression for the final misalignment using the principle of adiabatic invariance. The spin-orbit misalignment directly impacts the gravitational waveform, and can be used to constrain the formation scenarios of BH binaries and dynamical influences of external companions.

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Bin Liu, Dong Lai. 2017-06-07. Spin-Orbit Misalignment of Merging Black-Hole Binaries with Tertiary Companions. https://doi.org/10.3847/2041-8213/aa8727

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