3D Structure of the Magnetosheath Jets: Global Hybrid-Kinetic Simulations.

Over the past 25 years, several spacecraft have observed localized, high-pressure regions that sporadically appear in Earth’s magnetosheath, known as the “magnetosheath jets”. Despite previous analyses, the nature of these transient events remains elusive, marked by a range of uncertainties. These uncertainties mainly stem from the fact that oversimplified assumptions have been made in earlier analyses, where the jets are often portrayed as basic cylinder-like structures. This simplification is primarily because of two reasons: First, spacecraft observations in specific magnetosheath locations couldn't comprehensively cover and explore large spatial areas, providing only a limited perspective on the jets. Second, previous models used to study magnetosheath jets were either two-dimensional (2D) spatial models or three-dimensional (3D) with reduced scales of the Earth's magnetosphere to minimize computational complexity when dealing with Earth.

In this study, we use Amitis, a high-performance, three-dimensional (3D in both configuration and velocity spaces), time-dependent hybrid-kinetic plasma model (kinetic ions, fluid electrons) that runs in parallel on Graphics Processing Units (GPUs). We present, for the first time, the global kinetic interaction between the solar wind and the entire magnetosphere of Earth using its true scales. Achieving this level of accuracy in kinetic modeling of the solar wind plasma interaction with Earth has been a long-standing challenge. Our 3D, time-dependent hybrid-kinetic simulations dispel the notion that the magnetosheath jets are simple cylinders. Instead, our simulations show that the magnetosheath jets exhibit complex and interconnected structures with dynamic 3D characteristics. As they move through the magnetosheath, they wrinkle, fold, merge, and split in complex ways before a subset reaches the magnetopause. Our findings are pivotal in advancing our understanding of magnetosheath jets and their significance in coupling between the solar wind and Earth's magnetosphere.