Supermassive Hot Jupiters Provide More Favourable Conditions for the Generation of Radio Emission via the Cyclotron Maser Instability - A Case Study Based on Tau Bootis b

TL;DR

This study explores how supermassive hot Jupiters, like Tau Bootis b, create favorable conditions for radio emission via the cyclotron maser instability, suggesting they are promising targets for radio observations due to their atmospheric and magnetic properties.

Contribution

It demonstrates that supermassive hot Jupiters have conditions conducive to radio emission, expanding the potential targets for radio detection beyond classical hot Jupiters.

Findings

Supermassive hot Jupiters have near-hydrostatic upper atmospheres.

Their magnetospheres may support cyclotron maser emission.

These planets are better candidates for radio observation than classical hot Jupiters.

Abstract

We investigate under which conditions supermassive hot Jupiters can sustain source regions for radio emission, and whether this emission could propagate to an observer outside the system. We study Tau Bootis b-like planets (a supermassive hot Jupiter with 5.84 Jupiter masses and 1.06 Jupiter radii), but located at different orbital distances (between its actual orbit of 0.046 AU and 0.2 AU). Due to the strong gravity of such planets and efficient radiative cooling, the upper atmosphere is (almost) hydrostatic and the exobase remains very close to the planet, which makes it a good candidate for radio observations. We expect similar conditions as for Jupiter, i.e. a region between the exobase and the magnetopause that is filled with a depleted plasma density compared with cases where the whole magnetosphere cavity is filled with hydrodynamically outward flowing ionospheric plasma. Thus, unlike classical hot Jupiters like the previously studied planets HD 209458b and HD 189733b, supermassive hot Jupiters should be in general better targets for radio observations.