Do We Need to Consider Electrons' Kinetic Effects to Properly Model a Planetary Magnetosphere: The Case of Mercury. Issue 4 (22nd April 2022)

• Record Type: Journal Article
• Authors: Lapenta, Giovanni; Schriver, David; Walker, Raymond J.; Berchem, Jean; Echterling, Nicole F.; El Alaoui, Mostafa; Travnicek, Pavel
• Is Part Of: Journal of geophysical research. Volume 127:Issue 4(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-22
• Subjects: Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2021JA030241
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: The magnetosphere of Mercury is studied using an implicit full particle‐in‐cell simulation (PIC). We use a hybrid simulation where ions are full particles and electrons are considered as a fluid to start a PIC simulation where electrons are also particles and follow their distribution function. This approach allows us to estimate the changes introduced by the electron kinetic physics. We find that the overall macroscopic state of the magnetosphere of Mercury is little affected, but several physical processes are significantly modified in the full PIC simulation: the foreshock region is more active with more intense shock reformation, the Kelvin‐Helmholtz rippling effects on the nightside magnetopause are sharper, and the magnetotail current sheet becomes thinner than those predicted by the hybrid simulation. The greatest effect of the electron physics comes from the processes of particle energization. Both species, not just the electrons, are found to gain more energy when kinetic electron processes are included. The region with the most energetic plasma is found on the dusk side of the tail where magnetic flux ropes are formed due to reconnection. We find that the ion and electron energization is associated with the regions of reconnection and the development of kinetic instabilities caused by counter‐streaming electron populations. The resulting electron distributions are highly non Maxwellian, a process that neither MHD nor hybrid models can describe. Key Points: We study the magnetosphere of Mercury using an implicit, three‐dimensional, full particle‐in‐cell simulation The currents, interfaces and transition region are made thinner by the electron kinetic effects and become more active The greatest effect of including the electron physics is particle energization for both species