Exoplanets as Sub-GeV Dark Matter Detectors

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, with 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.

Automated summary

Exoplanets are presented as new targets for discovering dark matter. Through estimating the sensitivity of upcoming infrared telescopes, actionable searches for discovering or excluding dark matter are found. Dark matter with masses above about an MeV can be probed with exoplanets, with scattering cross sections stronger than existing limits.