Hot Jupiters and Super-Earths

TL;DR

This paper investigates how dynamical interactions and migration histories of hot Jupiters influence the presence of close-in super-Earths and the multiplicity of inner planetary systems, using N-body simulations and dynamical analysis.

Contribution

It introduces new N-body simulation results linking hot Jupiter migration to the absence of close super-Earths and analyzes outer system dynamics affecting inner system multiplicities.

Findings

Hot Jupiters' migration can destroy inner super-Earths.

Outer giant planets can reduce inner system multiplicity.

Dynamical scenarios explain observed single-planet systems.

Abstract

We explore the role of dynamics in shaping planetary system multiplicities, focussing on two particular problems. (1) We propose that the lack of close-in super-Earths in hot Jupiter systems is a signature of the migration history of the hot Jupiters and helps to discriminate between different mechanisms of migration. We present N-body simulations of dynamical migration scenarios where proto-hot Jupiters are excited to high eccentricities prior to tidal circularisation and orbital decay. We show that in this scenario, the eccentric giant planet typically destroys planets in the inner system, in agreement with the observed lack of close super-Earth companions to hot Jupiters. (2) We explore the role of the dynamics of outer systems in affecting the multiplicities of close-in systems such as those discovered by Kepler. We consider specifically the effects of planet--planet scattering and Kozai perturbations on an exterior giant planet on the architecture of the inner system, and evaluate the ability of such scenarios to reduce the inner system's multiplicity and contribute to the observed excess of single Kepler planets.