Nonthermal Emission from the Interaction of Magnetized Exoplanets with the Wind of Their Host Star

We study the nonthermal emission from the interaction between magnetized Jupiter-like exoplanets and the wind from their host star. The supersonic motion of planets through the wind forms a bow shock that accelerates electrons that produce nonthermal radiation across a broad wavelength range. We discuss three wind mass-loss rates: ${\dot{M}}_{{\rm{w}}}\sim {10}^{-14}$, 10−9, ${10}^{-6}\,{M}_{\odot }\,{\mathrm{yr}}^{-1}$ corresponding to solar-type, T Tauri, and massive O/B-type stars, respectively. We find that the expected radio synchrotron emission from a Jupiter-like planet is detectable by the Jansky Very Large Array and the Square Kilometre Array at $\sim 1\mbox{--}10\,\mathrm{GHz}$ out to a distance of ∼100 pc, whereas the infrared emission is detectable by the James Webb Space Telescope out to a similar distance. Inverse Compton scattering of the stellar radiation results in X-ray emission detectable by Chandra X-ray Observatory out to ∼150 pc. Finally, we apply our model to the upper limit constraints on V380 Tau, the first star–hot Jupiter system observed in radio wavelength. Our bow-shock model provides constraints on the magnetic field, the interplanetary medium, and the nonthermal emission efficiency in V380 Tau.