Planet-Planet Scattering Explains the Mass-Eccentricity Relation of Warm Jupiters

TL;DR

This paper explains the observed mass-eccentricity relation of warm Jupiters through planet-planet scattering, highlighting its implications for their origins, architectures, and potential for high-eccentricity tidal migration.

Contribution

It introduces a scattering-based framework to interpret warm Jupiter properties, linking their eccentricities and masses to dynamical interactions.

Findings

Warm Jupiters' eccentricity-mass correlation explained by scattering.

Predicted presence of additional planetary companions around warm Jupiters.

Scattering can produce high eccentricities leading to tidal migration.

Abstract

Warm giant planets with orbital periods of tens of days exhibit a positive correlation between mass and eccentricity. We interpret this trend as the outcome of planet-planet scattering, representing a transition from collision-dominated interactions among low-mass planets to ejection-dominated interactions among high-mass planets. This framework has important implications for warm Jupiter origins. It suggests that warm Jupiters originate from compact, multi-planet configurations. The dynamical interactions that shape their present-day architectures likely occur near their current semimajor axes, regardless of whether warm Jupiters formed through convergent disk-driven migration or in-situ formation. We argue that several observed properties of warm Jupiter systems, including the eccentricity bimodality, the mass-eccentricity relation, and generally low stellar obliquities, can be explained by this picture. We further predict that not only circular warm Jupiters, but also eccentric warm Jupiters, should frequently have additional planetary companions that are detectable through radial velocity observations. Finally, scattering can produce eccentricities high enough to trigger high-eccentricity tidal migration, potentially explaining the emerging population of proto-hot Jupiters on tidal migration tracks.