Precessional dynamics of black hole triples: binary mergers with near-zero effective spin

摘要: The binary black hole mergers detected by Advanced LIGO/Virgo have shown no evidence of large spins. However, because best measures the effective combination the two spins along orbital angular momentum (Xeff), it is difficult to distinguish between binaries with slowly-spinning holes and binaries with lying in plane. Here, we study spin dynamics for with a distant companion. For initially aligned angular momentum binary, find that Xeff \freezes" near zero as orbit decays through emission gravitational waves. Through a population study, show that this process predominantly leads merging near-zero Xeff. We conclude if were formed triples, then this would explain their low _eff without need invoke near-zero or initially large spin-orbit angles.