Multipoint measurements of Short Large-Amplitude Magnetic Structures (SLAMS) and their role in Earth´s bow shock dynamics and ion energization

The interaction between the solar wind and the geomagnetic field results in a bow shock where the solar wind brakes down to a submagnetosonic velocity. The properties of the shock depend strongly on the direction of the solar wind magnetic field.

When this is close to parallel to the bow shock normal, an extended turbulent foreshock region is formed in front of the bow shock (which is referred to as quasi-parallel in this case).

An important type of structure in the foreshock is Short Large-Amplitude Magnetic Structures (SLAMS), which can have a strong influence on the formation, properties, and dynamics of the bow shock and associated particle energization. In spite of their importance, many properties of SLAMS are still not well known.

In this project, our aim is to address the following science questions (SQ), using the multi-spacecraft measurements of the Cluster and MMS missions:SQ1: What are the spatio-temporal properties of SLAMS? What is the size and morphology of SLAMS?

How do they depend on upstream conditions, such as solar wind Mach number and the strength and direction of the interplanetary magnetic field?

On what time scales do they form and develop, and how far upstream of the bow shock do they exist?SQ2: How do SLAMS interact with the bow shock?SLAMS have been suggested to be fundamental building blocks of the quasi-parallel bow shock. SLAMS have a phase velocity that is smaller than or comparable to the solar wind velocity.

In order to merge with the bow shock, the phase velocity must be equal and opposite to the solar wind flow velocity. For which SLAMS does this happen? Does it depend on the SLAMS amplitude, Mach number or other properties? Some SLAMS may not attain the phase velocity needed to merge with the bow shock.

Will they then penetrate the bow shock and end up in the downstream magnetosheath as plasmoids and magnetosheath jets? SQ3: What is the role of SLAMS in ion energization?

For Earth’s bow shock, the dynamics is more governed by ions than electrons  One aspect of these dynamics is the acceleration of ions to high energies. The role of SLAMS in this ion energization is not clear. How often are SLAMS associated with local ion energization? What are the details of these processes and what is the role of electric fields?

Does SLAMS energization help increasing the efficiency of particle acceleration at the bow shock?The SQ will be addressed using the multi-point measurements of the Cluster and MMS satellites. This research will be performed by a PostDoc, during three years.

The project will increase the knowledge of the under-investigated SLAMS phenomenon, which may play an important role on the solar wind-magnetosphere interaction. It will also provide baseline knowledge for future research on astrophysical shocks and exoplanet bow shocks.