Authors: Maria Elena Innocenti (Ruhr University Bochum), Alfredo Micera (Ruhr University Bochum), Daniel Verscharen (UCL), Anna Tenerani (UTAustin), Marco Velli (UCLA)

Global electron dynamics in the heliosphere

In this contribution, I will focus on the fundamental role of electrons in Heliophysics. Even if electron scales are order of magnitude smaller, in space and time, than global heliospheric scales, electrons, due to their supersonic nature, are a truly global species: electron circulation patterns in the heliosphere, predicted long ago by exospheric models, have been recently observed, indirectly, through electron velocity distribution functions measured by Parker Solar Probe and Solar Orbiter, and through the re-evaluation of Helios observations. 

Electrons are excellent probes of heliospheric conditions: they provide information on the coronal regions of origin of solar wind parcels and on magnetic field line connectivity, and give indirect hints to the existence, in the solar wind, of different heating mechanisms for ions and electrons. Furthermore, suprathermal electrons carry the solar wind heat flux: electron processes regulate the heliospheric energy budget.

It is then fundamental to understand what controls electron evolution in the heliosphere. Electron modeling in the heliosphere focuses either on their global nature (i.e., exospheric models, fully collisionless or partially collisional) or on small-scale wave/particle interactions (Particle-In-Cell, PIC models), given their role in heat flux regulation. Limited large scale information can be introduced in PIC models, as done for example in Expanding Box PIC codes. To conclude my contribution, I will review some recent results in the simulation of the interaction between global and small-scale electron processes, and highlight its importance for heat flux regulation in the solar wind.