Electron acceleration by magnetosheath jet-driven bow waves

When they supermagnetosonically compress the ambient magnetosheath plasma, a bow wave or shock can form ahead of them. Such a bow wave was recently observed to accelerate ions and possibly electrons.

The ion acceleration process was previously analyzed, but the electron acceleration process remains largely unexplored. Here we use multipoint observations by Time History of Events and Macroscale during Substorms from three events to determine whether and how magnetosheath jet-driven bow waves can accelerate electrons. We show that when suprathermal electrons in the ambient magnetosheath convect toward a bow wave, some electrons are shock-drift accelerated and reflected toward the ambient magnetosheath and others continue moving downstream of the bow wave resulting in bidirectional motion.