Statistical Analysis of the Dearth of Super-eccentric Jupiters in the Kepler Sample

TL;DR

This study tests the high-eccentricity migration theory for hot Jupiter formation by comparing predicted and observed numbers of super-eccentric Jupiters in Kepler data, finding significant discrepancies.

Contribution

It provides a statistical analysis that challenges the dominance of high-eccentricity migration in hot Jupiter formation, suggesting other mechanisms are more prevalent.

Findings

Observed super-eccentric Jupiters are fewer than predicted by high-eccentricity migration models.

High-eccentricity migration can explain at most 62% of Kepler hot Jupiters.

The data rejects the high-eccentricity migration hypothesis with 94.3% confidence.

Abstract

Hot Jupiters may have formed in situ, or been delivered to their observed short periods through one of two categories of migration mechanisms: disk migration or high-eccentricity migration. If hot Jupiters were delivered by high-eccentricity migration, we would expect to observe some "super-eccentric" Jupiters in the process of migrating. We update a prediction for the number of super-eccentric Jupiters we would expect to observe in the Kepler sample if all hot Jupiters migrated through high-eccentricity migration and estimate the true number observed by Kepler. We find that the observations fail to match the prediction from high-eccentricity migration with 94.3% confidence and show that high-eccentricity migration can account for at most ~62% of the hot Jupiters discovered by Kepler.