Effects of electron particle physics in global planetary models

We compare global models of Mercury done with the hybrid (particle ions and fluid electrons) and full kinetic (particles are used for both electrons and ions) models. We use the implicit particle in cell method based on the ECsim algorithm [1]. We study how energy exchanges in the magnetosphere of the planet are changed by representing the electrons as particles. We observe a more powerful energy exchange due to the presence of stronger features, larger more localised electron currents and sharper interfaces. The electron and also the ion energisation  is more intense leading to an overall increase of the energy transfer from the solar wind to the planetary magnetosphere. The electron distribution is far from Maxwellian, showing effects that cannot be captured by hybrid models such as the the presence of crescents, flat-top and multi beam distributions. Full particle models also provide more accurate description of reconnection. Using the electron agyrotropy, the new Lorentz indicator [2] and a new machine learning method [3], we investigate how reconnection is linked with current sheets, studying where and when reconnection happens and distinguishing electron from ion- scale reconnection. 

 

 

[1] Lapenta, G., Schriver, D., Walker, R. J., Berchem, J., Echterling, N. F., El Alaoui, M., & Travnicek, P. (2022). Do We Need to Consider Electrons' Kinetic Effects to Properly Model a Planetary Magnetosphere? The Case of Mercury. Journal of Geophysical Research: Space Physics, 127(4), e2021JA030241.

[2] Lapenta, G. (2021). Detecting reconnection sites using the Lorentz Transformations for electromagnetic fields. The Astrophysical Journal, 911(2), 147.

[3] Lapenta, G., Goldman, M., Newman, D. L., & Eriksson, S. (2022). Formation and Reconnection of Electron Scale Current Layers in the Turbulent Outflows of a Primary Reconnection Site. The Astrophysical Journal, 940(2), 187.