Parametric Properties and Impacts of Spontaneous Hot Flow Anomalies

Abstract:

Using global hybrid (kinetic ions, fluid electron) simulations, parametric dependencies of spontaneous hot flow anomalies (SHFAs) at the quasi-parallel bow shock and their impact on magnetosheath plasma are investigated. In particular, the effects of solar wind Mach number and direction of the interplanetary magnetic field (IMF) are examined. Simulations with solar wind Mach number of 3 and small IMF cone angles show sporadic formation of SHFAs. Increasing the Mach number shows the formation of large number of SHFAs. We use the properties of these SHFAs to show that their duration does not depend on Mach number indicating that the size SHFAs increases with solar wind Mach number. Similarly, the level of the solar wind deceleration associated with SHFAs increases with Mach number as does their core ion temperature. We also show that the edges of SHFAs are associated with jumps in magnetic field strength that increase with shock Mach number as does the rate of SHFA formation. Simulations with IMF cone angle of 90^o show that SHFAs form at the quasi-parallel bow shock provided the shock Alfvén Mach number is ~>3, indicating that SHFAs can form at all IMF cone angles. Finally, we show that the interaction of SHFAs with the bow shock results in spatial and temporal changes in plasma and field conditions in the magnetosheath whose strength increases with solar wind Mach number. The details of this interaction are described in this presentation.