Planet-bound dark matter and the internal heat of Uranus, Neptune, and hot-Jupiter exoplanets

TL;DR

This paper proposes that accretion of planet-bound dark matter could explain the internal heat of giant planets and exoplanets, with Uranus's low heat possibly due to dark matter loss from a collision.

Contribution

It introduces a novel hypothesis that planet-bound dark matter accretion significantly influences planetary internal heat, including a potential explanation for Uranus's anomalously low heat.

Findings

Dark matter accretion could be a major heat source for Jovian planets.

Uranus's low heat may result from dark matter loss after a collision.

The model applies to both self-annihilating and non-self-annihilating dark matter.

Abstract

We suggest that accretion of planet-bound dark matter by the Jovian planets, and by hot-Jupiter exoplanets, could be a significant source of their internal heat. The anomalously low internal heat of Uranus would then be explained if the collision believed to have tilted the axis of Uranus also knocked it free of most of its associated dark matter cloud. Our considerations focus on the efficient capture of non-self-annihilating dark matter, but could also apply to self-annihilating dark matter, provided the capture efficiency is small enough that the earth heat balance constraint is obeyed.