Moving Mesh Magnetohydrodynamics: Magnetic Processes in Star Formation and Cosmology

Abstract

Magnetohydrodynamic (MHD) processes are ubiquitous in our Universe. From the largest cosmological scales where primordial magnetic fields may fill the cosmic web to scales of the formation of individual stars, the magnetic field affects the observable signatures of these systems and their dynamics. Numerical simulations of MHD processes are vital to gain an understanding of the fundamental physical processes that shape these systems and the physical parameters that describe them. Such simulations can be numerically challenging however, due to the large dynamic range in densities seen in these systems. Furthermore, the divergence-free condition on the magnetic field poses additional numerical challenges for evolving the field at the discretized level. I develop a moving mesh MHD method that overcomes these two primary computational challenges. The moving mesh framework allows the code to automatically and adaptively follow material as it moves and collapses under self-gravity. Furthermore, I formulate the numerical MHD solver as a constraint transport algorithm that maintains Maxwell's law of a divergence-free magnetic field at the level of machine-precision. I present simulation studies of magnetic field growth and amplification on scales of cosmology and star formation. Despite their differences, these two systems share some commonalities as they are both systems collapsing under self-gravity with magneto-turbulent processes present, which are responsible for how the magnetic field ultimately grows. Fundamental physical processes in these systems and their observational signatures are investigated in this dissertation.