Inferring Whistler-Mode Chorus Wave Source Regions in the Martian Mini-Magnetospheres

Martian mini-magnetospheres contain whistler-mode chorus waves potentially contributing to atmospheric escape, analogous to the Earth's inner magnetosphere. At Earth, the chorus waves have been found to originate from the near-equatorial region spanning approximately 2% of the entire magnetic field line length. However, because of the lack of wave Poynting flux measurements, the Martian chorus source region remains unclear. By comparing the frequency dependence between observed wave power and modeled linear growth rates, we present the first attempt to explore the chorus wave source distribution along the Martian mini-magnetospheric field lines. Our data-to-model comparisons support that these waves are not generated by a single source tightly confined near the magnetic strength minimal location but by intermittent or continuous sources spanning up to 40% of the entire field line length. These results imply that the Martian mini-magnetospheres could have more active energy transfer processes mediated by whistler-mode chorus waves than the expectation. Atmospheric escape is a critical process for the evolution of the surface habitability of terrestrial planets in our solar system or beyond. Analogous to the Earth's inner magnetosphere, the Martian mini-magnetospheres formed by crustal magnetic fields contain whistler-mode chorus waves which have the potential to contribute to atmospheric escape. However, because of the lack of wave Poynting flux measurements, where the Martian chorus waves are generated remains unclear. By comparing the frequency dependence between the observed wave power spectral densities and the modeled linear growth rates, we present the first attempt to explore the distribution of chorus wave sources along the magnetic field lines of the Martian mini-magnetospheres. We show that these Martian chorus waves are generated by intermittent or continuous sources spanning up to 40% of the entire magnetic field line length, in contrast to the Earth's inner magnetospheric chorus waves with a single near-equatorial source spanning approximately 2% of the entire field line length. These results imply that the Martian mini-magnetospheres could have more active energy transfer processes mediated by whistler-mode chorus waves than the expectation from analogy to the Earth's magnetosphere. Chorus wave sources are located by matching the frequency dependence between the modeled linear growth rates and the observed powerMartian mini-magnetospheres contain continuous or intermittent wave sources spanning up to 40% of the entire magnetic field line lengthMartian mini-magnetospheres could have more active energy transfer processes mediated by chorus than the expectation