Exoplanets as Sub-GeV Dark Matter Detectors

TL;DR

This paper proposes using exoplanets as detectors for sub-GeV dark matter by analyzing heat signatures caused by dark matter interactions, offering a novel method with sensitivity surpassing current limits.

Contribution

It introduces a new approach to detect dark matter via exoplanet heating, expanding the search to lower mass ranges and stronger cross sections than previous methods.

Findings

Dark matter can be detected through exoplanet heat signatures.

Exoplanets can probe dark matter masses above about 1 MeV.

Sensitivity exceeds existing limits by up to six orders of magnitude.

Abstract

We present exoplanets as new targets to discover Dark Matter (DM). Throughout the Milky Way, DM can scatter, become captured, deposit annihilation energy, and increase the heat flow within exoplanets. We estimate upcoming infrared telescope sensitivity to this scenario, finding actionable discovery or exclusion searches. We find that DM with masses above about an MeV can be probed with exoplanets at DM-proton and DM-electron scattering cross sections down to about $10^{-37}$cm$^2$, stronger than existing limits by up to six orders of magnitude. Supporting evidence of a DM origin can be identified through DM-induced exoplanet heating correlated with Galactic position, and hence DM density. This provides new motivation to measure the temperature of the billions of brown dwarfs, rogue planets, and gas giants peppered throughout our Galaxy.