Lecturer: Sofia Bergman (KTH) Date: 2025-09-18 10:00 Place: Aniara
Statistical properties of Short Large-Amplitude Magnetic Structures (SLAMS) in the foreshock of Earth
Sofia Bergman
KTH Royal Institute of Technology
Abstract:
Shock waves are found in many different environments throughout the universe. Most of them can only be studied using remote methods, with the exception of the shocks found in our own solar system. The planetary bow shocks, created when the supersonic solar wind encounters the planets and is slowed to subsonic velocities, are frequently studied and used as templates to understand other shocks in the universe.
Depending on the angle between the interplanetary magnetic field and the bow shock normal, the shock is defined to be either quasi-perpendicular (angle > 45 degrees) or quasi-parallel (angle < 45 degrees). In the quasi-parallel regime, the upstream region magnetically connected to the shock, called the foreshock, is highly dynamic and characterized by various plasma instabilities and wave activity. Short Large-Amplitude Magnetic Structures (SLAMS) are non-linear isolated magnetic field signatures commonly observed in this region. Their formation process is still highly uncertain, but they are believed to grow from ultra-low frequency (ULF) waves which are common in the foreshock. SLAMS are suggested to be important for the formation of the quasi-parallel shock, influencing the properties and dynamics of the shock and also associated particle energization. However, many of the fundamental properties of these structures remain unknown.
In this work, we use data from the Cluster mission to statistically study the properties of SLAMS in the foreshock of Earth. We use both single-point and multi-point techniques to study their fundamental properties and the dependencies on the upstream environment and the solar cycle.
The seminar is also online. See emails for connection details.
Created 2025-09-08 16:55:34 by Mats Holmström Last changed 2025-09-15 12:55:51 by Mats Holmström
