Stability analysis in simulations of differentially rotating disks with global curvature effects

Abstract

Instability-driven turbulence plays a crucial role in explaining the accretion process and angular momentum transport in astrophysical disks. This thesis studies the drivers of non-linear transport in differentially rotating systems: instabilities. In particular, this thesis examines the stability of the Magneto-Rotational Instability (MRI) in the weak-field limit as well as the global non-axisymmetric Magneto-Curvature Instability (MCI) in the strong-field limit (Ebrahimi & Pharr ApJ 936, 2022). Unlike MRI, which is typically concentrated in flow shear regions, MCIs are global distinct low- frequency non-axisymmetric modes driven unstable by global differential rotation and spatial curvature. This thesis presents linear MHD simulations in an unstratified Keplerian cylinder at various Lunquist numbers and aspect ratios. These results are compared to ideal linear instability perturbation analysis, and an initial resistive perturbation analysis extension is presented. This work was supported by NSF.