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A New Statistical Solution to the Chaotic Three-Body Problem
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主讲人: Nick Stone (Hebrew University)
地点: Remote Talk
时间: 2021年11月18日(星期四)15:30-16:30
主持 联系人: Kohei Inayoshi
主讲人简介: I am a Senior Lecturer (US equivalent is Assistant Professor) at the Hebrew University of Jerusalem, and have been since 2019. Earlier in my career, I was a postdoctoral researcher and then Einstein Fellow at Columbia University in NYC (2013-2018). I did my PhD at Harvard University with Avi Loeb as my PhD advisor; before that, I did my undergraduate studies at Cornell University in Physics/Mathematics/Economics.

The three-body problem is arguably the oldest open question in astrophysics and has resisted a general analytic solution for centuries. Various forms of perturbation theory provide solutions in portions of parameter space, but only where hierarchies of masses and/or separations exist. Numerical integrations show that bound, non-hierarchical triple systems of Newtonian point particles will almost always disintegrate into a single escaping star and a stable bound binary, but the chaotic nature of the three-body problem prevents the derivation of analytic formulae that deterministically map initial conditions to final outcomes. Chaos, however, also motivates the assumption of ergodicity. I will present a newstatistical solutionto the non-hierarchical three-body problem that is derived using the ergodic hypothesis and that provides closed-formdistributionsof outcomes (for example, binary orbital elements) when given the conserved integrals of motion. We compare our outcome distributions to large ensembles of numerical three-body integrations and find good agreement, so long as we restrict ourselves to "resonant" encounters (the roughly 50% of scatterings that undergo chaotic evolution). In analysing our scattering experiments, we identify "scrambles" (periods of time in which no pairwise binaries exist) as the key dynamical state that ergodicizes a non-hierarchical triple system. I will briefly discuss how the generally super-thermal distributions of survivor binary eccentricity that we predict have applications to many astrophysical scenarios. For example, non-hierarchical triple systems produced dynamically in dense star clusters are a primary formation channel for black-hole mergers, but the rates and properties of the resulting gravitational waves depend on the distribution of post-disintegration eccentricities.

Speaker: Nick Stone (Hebrew University)

Place: Remote Talk

Host: Kohei Inayoshi

Time: Thursday, November 18, 2021, 3:30PM - 4:30PM

Biography: I am a Senior Lecturer (US equivalent is Assistant Professor) at the Hebrew University of Jerusalem, and have been since 2019. Earlier in my career, I was a postdoctoral researcher and then Einstein Fellow at Columbia University in NYC (2013-2018). I did my PhD at Harvard University with Avi Loeb as my PhD advisor; before that, I did my undergraduate studies at Cornell University in Physics/Mathematics/Economics.