A non-local magneto-curvature instability in differentially rotating astrophysical disks

Flow-driven instabilities are required to generate the potential turbulence in astrophysical rotators, and therefore to drive nonlinear dynamics, such as momentum transport, reconnection, heating, and dynamo processes. In a differentially rotating system, while exponentially growing axisymmetric magnetorotational instability (MRI) modes could be a partial driver, the onset and sustainment of non-axisymmetric perturbations are not well understood. Moreover, only global models with spatially varying fields (both magnetic and rotational) can offer the richest mode spectrum, mainly as the result of resonances in the system. We have recently uncovered a new non-local mode, a magneto-curvature instability (Ebrahimi&Pharr ApJ 2022; https://doi.org/10.3847/1538-4357/ac892d). This instability is triggered due to Alfven-continuum unstable modes in the presence of non-local effects of the global spatial curvature of flow shear and magnetic field. I will present the linear analysis, as well as the nonlinear results. In particular, I will show that as the field strength is increased a transition from MRI-driven turbulence to a state dominated by global nonaxisymmetric modes is obtained.