Plasma Mechanism of Radio Emission Generation at the Bow Shock of the Exoplanet HD 189733b

Abstract

This study evaluates the possibility of efficient radio emission generation in the bow shock region of hot Jupiter-type exoplanets. As a source of energetic electrons, the shock drift acceleration mechanism at a quasi-perpendicular shock is proposed. Electrons reflected and accelerated by the shock propagate through the relatively dense stellar wind plasma and excite plasma waves; therefore, a plasma emission mechanism is considered as the source of the resulting radio waves. Using the bow shock of the hot Jupiter HD 189733b as a case study, the properties of the energetic electron beam, the excited plasma waves, and the resulting radio frequencies are estimated. An energy-based analysis is carried out to identify the range of stellar wind parameters for which radio emission from the bow shock of the exoplanet HD 189733b could be detectable by modern astronomical instruments.