Chaos in the Test Particle Eccentric Kozai–lidov Mechanism

Li, Gongjie; Naoz, Smadar; Holman, M.; Loeb, Abraham

doi:10.1088/0004-637x/791/2/86

Cited by 138 publications

(123 citation statements)

References 36 publications

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“…The octupole potential of the outer companion further contributes to the secular dynamics of the system, introducing under some conditions even higher maximum eccentricities and orbit flipping (Ford et al 2000;Naoz et al 2013a), as well as chaotic orbital evolution (Li et al 2014). The "strength" of the octupole potential (relative to the quadrupole) is determined by…”

Section: Setup and Equationsmentioning

confidence: 99%

Eccentricity and spin-orbit misalignment in short-period stellar binaries as a signpost of hidden tertiary companions

Anderson

Lai

Storch

2017

Monthly Notices of the Royal Astronomical Society

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Eclipsing binaries are observed to have a range of eccentricities and spin-orbit misalignments (stellar obliquities). Whether such properties are primordial, or arise from post-formation dynamical interactions remains uncertain. This paper considers the scenario in which the binary is the inner component of a hierarchical triple stellar system, and derives the requirements that the tertiary companion must satisfy in order to raise the eccentricity and obliquity of the inner binary. Through numerical integrations of the secular octupole-order equations of motion of stellar triples, coupled with the spin precession of the oblate primary star due to the torque from the secondary, we obtain a simple, robust condition for producing spin-orbit misalignment in the inner binary: In order to excite appreciable obliquity, the precession rate of the stellar spin axis must be smaller than the orbital precession rate due to the tertiary companion. This yields quantitative requirements on the mass and orbit of the tertiary. We also present new analytic expressions for the maximum eccentricity and range of inclinations allowing eccentricity excitation (Lidov-Kozai window), for stellar triples with arbitrary masses and including the non-Keplerian potentials introduced by general relativity, stellar tides and rotational bulges. The results of this paper can be used to place constraints on unobserved tertiary companions in binaries that exhibit high eccentricity and/or spin-orbit misalignment, and will be helpful in guiding efforts to detect external companions around stellar binaries. As an application, we consider the eclipsing binary DI Herculis, and identify the requirements that a tertiary companion must satisfy to produce the observed spin-orbit misalignment.

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Section: Setup and Equationsmentioning

confidence: 99%

Eccentricity and spin-orbit misalignment in short-period stellar binaries as a signpost of hidden tertiary companions

Anderson

Lai

Storch

2017

Monthly Notices of the Royal Astronomical Society

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“…only for marginally hierarchical systems, e.g. Li et al 2014). This implies larger possible variations in inclinations at times of maximum eccentricity and therefore less peaked distributions of the obliquity after tidal dissipation has shrunk the planetary orbit.…”

Section: Stellar Obliquitiesmentioning

confidence: 99%

On the formation of hot and warm Jupiters via secular high-eccentricity migration in stellar triples

Hamers

2017

Mon. Not. R. Astron. Soc.

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Hot Jupiters (HJs) are Jupiter-like planets orbiting their host star in tight orbits of a few days. They are commonly believed not to have formed in situ, requiring inwards migration towards the host star. One of the proposed migration scenarios is secular high-eccentricity or high-e migration, in which the orbit of the planet is perturbed to high eccentricity by secular processes, triggering strong tidal evolution and orbital migration. Previous theoretical studies have considered secular excitation in stellar binaries. Recently, a number of HJs have been observed in stellar triple systems. In the latter, the secular dynamics are much richer compared to stellar binaries, and HJs could potentially be formed more efficiently. Here, we investigate this possibility by modeling the secular dynamical and tidal evolution of planets in two hierarchical configurations in stellar triple systems. We find that the HJ formation efficiency is higher compared to stellar binaries, but only by at most a few tens of per cent. The orbital properties of the HJs formed in the simulations are very similar to HJs formed in stellar binaries, and similarly to studies of the latter we find no significant number of warm Jupiters. HJs are only formed in our simulations for triples with specific orbital configurations, and our constraints are approximately consistent with current observations. In future, this allows to rule out high-e migration in stellar triples if a HJ is detected in a triple grossly violating these constraints.

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“…In the standard theory of hierarchical triple systems, for an eccentric outer orbit, the inner binary can reach high eccentricities and undergo chaotic evolution of its orientation for a large range of initial mutual inclinations of inner to outer orbit (e.g., Ford et al 2000;Lithwick & Naoz 2011;Katz et al 2011;Li et al 2014). However, in the environment of a MBH, extremely high eccentricities are difficult to achieve for most binaries (Antonini & Perets 2012).…”

Section: Introductionmentioning

confidence: 99%

Greatly Enhanced Merger Rates of Compact-object Binaries in Non-spherical Nuclear Star Clusters

Petrovich

Antonini

2017

ApJ

197

181

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The Milky Way and a significant fraction of galaxies are observed to host a central Massive Black Hole (MBH) embedded in a non-spherical nuclear star cluster. We study the secular orbital evolution of compact-object binaries in these environments and characterize the excitation of extremely large eccentricities that can lead to mergers by gravitational radiation. We find that the eccentricity excitation occurs most efficiently when the nodal precession timescale of the binary's orbit around the MBH due to the non-spherical cluster becomes comparable (within a factor of ∼ 10) to the timescale on which the binary is torqued by the MBH due to the Lidov-Kozai (LK) mechanism. We show that in this regime the perturbations due to the cluster increase the fraction of systems that reach extreme eccentricities (1 − e ∼ 10 −4 − 10 −6 ) by a factor of ∼ 10 − 100 compared to the idealized case of a spherical cluster, increasing the merger rates of compact objects by a similar factor. We identify two main channels that lead to this extreme eccentricity excitation: (i) chaotic diffusion of the eccentricities due to resonance overlap; (ii) cluster-driven variations of the mutual inclinations between the binary orbit and its center-of-mass orbit around the MBH, which can intensify the LK oscillations. We estimate that our mechanism can produce black hole-black hole and black hole-neutron star binary merger rates of up to ≈ 15 Gpc −3 yr −1 and ≈ 0.4 Gpc −3 yr −1 , respectively. Thus, we propose the cluster-enhanced Lidov-Kozai mechanism as a new channel for the merger of compact-object binaries, competing with scenarios that invoke isolated binary evolution or dynamical formation in globular clusters.

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Chaos in the Test Particle Eccentric Kozai–lidov Mechanism

Cited by 138 publications

References 36 publications

Eccentricity and spin-orbit misalignment in short-period stellar binaries as a signpost of hidden tertiary companions

Eccentricity and spin-orbit misalignment in short-period stellar binaries as a signpost of hidden tertiary companions

On the formation of hot and warm Jupiters via secular high-eccentricity migration in stellar triples

Greatly Enhanced Merger Rates of Compact-object Binaries in Non-spherical Nuclear Star Clusters

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