Dyncamics of Debris Discs Around Eccentric Binaries

Abstract

Debris disks are extended distributions of dust and debris which obtain in the course of planet formation. They can be thought of as analogs of the Solar System's asteroid and Kuiper belts [with significant differences in age, size and mass]. Observations of debris discs have revealed a variety of intriguing structures: gaps, warps, eccentric rings, etc. They are typically attributed to the dynamical response of the host disc to massive perturbers, such as embedded planets and/or stellar companions. While interactions between planets and debris discs have been extensively studied, most investigations treat the disc as a collection of massless planetesimals which are perturbed but non-perturbing. In this thesis, we study the effect of the disc’s gravitational back-reaction on an embedded planet, all the while neglecting the disc's self-gravity. Pearce and Wyatt 2015 were first to consider this regime in an exoplanetary setting, referring to it as the semi-active limit. In our work, we deploy a mix of numerical simulations and perturbative analysis to elucidate dynamical processes at play in the semi-active coupling between a disc and an inner eccentric binary. We recover particle equilibria, and phase space structures in various limits, then correlate them with simulated kinetics as we zero-in on key transport mechanisms. In so doing, we cover essential ground towards a kinetic theory for the evident relaxation to lopsided equilibria in the semi-active limit, while suggesting potential avenues and questions for future exploration.