The heating efficiency of hot Jupiters from a data-driven perspective

TL;DR

This paper investigates the observed single-peak distribution of heating efficiency in hot Jupiters, revealing it results from physical processes like stellar flux and planetary mass effects rather than specific theoretical models.

Contribution

It uncovers the physical origins of the heating efficiency distribution, linking it to observable properties without relying on particular theoretical assumptions.

Findings

Heating efficiency correlates with stellar effective temperature.

Increase in incident stellar flux raises heating efficiency.

Higher planetary mass decreases heating efficiency due to gravitational binding energy.

Abstract

The inflated radii of hot Jupiters have been explored by various theoretical mechanisms. By connecting planetary thermal evolution models with the observed properties of hot Jupiters using hierarchical Bayesian models, a theoretical parameter called the heating efficiency has been introduced to describe the heating of the interiors of these planets. Previous studies have shown that the marginal distribution of this heating efficiency parameter has a single-peak distribution along the planetary equilibrium temperature (Teq). Since the foundation of these Bayesian inference models are the observed properties of hot Jupiters, there must be a corresponding feature in the observed data that leads to the inferred single-peak distribution of the heating efficiency. This study aims to find the underlying cause of the single-peak heating efficiency distribution without relying on specific theoretical models. By analyzing the relationship between different observed physical properties, we obtained a similar single-peak distribution of the radius expansion efficiency of hot Jupiters along Teq, which can be explained by the correlation with the stellar effective temperature. However, a detailed investigation suggests that this single-peak distribution is actually the result of straightforward physical processes. Specifically, the increase in heating efficiency can be attributed to the increase in incident stellar flux, while the decrease in heating efficiency can be attributed to the rise in gravitational binding energy associated with the increase in planetary mass.