# Three dimensional Particle-in-Cell (PIC) simulations of the 67P environment

Andrey Divin, Jan Deca, Pierre Henri, Mihaly Horanyi, Stefano Markidis, Giovanni Lapenta, Vyacheslav Olshevsky, Anders Eriksson

► To cite this version:

Andrey Divin, Jan Deca, Pierre Henri, Mihaly Horanyi, Stefano Markidis, et al. Three dimensional Particle-in-Cell (PIC) simulations of the 67P environment. 19th EGU General Assembly, Apr 2017, Vienne, Austria. pp.EGU2017-1556-1. insu-03568159

HAL Id: insu-03568159

https://insu.hal.science/insu-03568159

Submitted on 12 Feb 2022

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# Three dimensional Particle-in-Cell (PIC) simulations of the 67P environment

Andrey Divin (1), Jan Deca (2,7), Pierre Henri (3), Mihaly Horanyi (2,7), Stefano Markidis (4), Giovanni Lapenta (5), Vyacheslav Olshevsky (5), and Anders Eriksson (6)

(1) St. Petersburg State University, St. Petersburg, Russia (andrey.div@gmail.com), (2) Laboratory for Atmospheric and Space Physics (LASP), University of Colorado, Boulder, USA, (3) LPC2E - CNRS, 3A avenue de la Recherche Scientifique, Orléans Cedex 2, France, (4) Department of Computational Science and Technology, KTH Royal Institute of Technology, Stockholm, Sweden, (5) Department of Mathematics, KU Leuven, Leuven, Belgium, (6) Swedish Institute of Space Physics, Uppsala, Sweden, (7) Institute for Modeling Plasma, Atmospheres and Cosmic Dust, NASA/SSERVI, USA

ESA's Rosetta orbiter spacecraft escorted comet 67P/Churyumov-Gerasimenko for two years, carrying 21 scientific instruments. Five of those were dedicated to plasma measurements. The mission revealed for the first time, and in unprecedented detail, the fascinating evolution of a comet and its interaction with our Sun as it races along its 6.45yr elliptical orbit around the Sun.

Using a self-consistent 3-D fully kinetic electromagnetic particle-in-cell approach, we focus on the global cometary environment and, in particular, on the collisionless electron-kinetic interaction. We include cometary ions and electrons produced by the ionization of the outgassing cometary atmosphere in addition to the solar wind ion and electron plasma flow. We approximate mass-loading of the cold cometary ion and electron populations using a $1/r$ relation with distance to the comet with a total neutral production rate of $Q = 10^{26} s^{-1}$.

Our simulation results disentangle for the first time the kinetic ion and electron dynamics of the solar wind interaction with a weakly outgassing comet. The simulated global structure of the solar wind-comet interaction **confirms** the results reported in hybrid simulations of the induced cometary magnetosphere. Moreover, we show that cometary and solar wind electrons neutralize the solar wind protons and cometary ions, respectively, in the region of influence around the comet, representing to first order a four-fluid behavior. The electron energy distribution close to the comet is shown to be a mix of cometary and solar wind electrons that appear as, respectively, a thermal and a suprathermal components. Analyzing ion and electron energy distribution functions, and comparing with plasma measurements from ESA's Rosetta mission to comet 67P/Churyumov-Gerasimenko, we conclude that a detailed kinetic treatment of the electron dynamics is critical to fully capture the complex physics of mass-loading plasmas.