Observable Predictions from Perturber-coupled High-eccentricity Tidal Migration of Warm Jupiters

TL;DR

This paper explores a migration mechanism for warm Jupiters involving perturbing companions causing high-eccentricity oscillations, and assesses the detectability of such companions through various observational methods.

Contribution

It introduces a model for perturber-coupled high-eccentricity tidal migration and evaluates the observational signatures of these perturbers in existing data.

Findings

A small percentage of perturbers should be detectable in Kepler light curves.

Most perturbers are detectable via precise radial velocity measurements over 3 months.

If no companions are found, this migration pathway is likely not dominant.

Abstract

The origin of warm Jupiters (gas giant planets with periods between 10 and 200 days) is an open question in exoplanet formation and evolution. We investigate a particular migration theory in which a warm Jupiter is coupled to a perturbing companion planet that excites secular eccentricity oscillations in the warm Jupiter, leading to periodic close stellar passages that can tidally shrink and circularize its orbit. If such companions exist in warm Jupiter systems, they are likely to be massive and close-in, making them potentially detectable. We generate a set of warm Jupiter-perturber populations capable of engaging in high-eccentricity tidal migration and calculate the detectability of the perturbers through a variety of observational metrics. We show that a small percentage of these perturbers should be detectable in the Kepler light curves, but most should be detectable with precise radial velocity measurements over a 3-month baseline and Gaia astrometry. We find these results to be robust to the assumptions made for the perturber parameter distributions. If a high-precision radial velocity search for companions to warm Jupiters does not find evidence of a significant number of massive companions over a 3-month baseline, it will suggest that perturber-coupled high-eccentricity migration is not the predominant delivery method for warm Jupiters.