2023/09/14 by Rodman, Payton E., Reynolds, Christopher S.
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Solar and Stellar Astrophysics (astro-ph.SR)
paper · doi:10.48550/arxiv.2309.07953
We present results from a pair of high resolution, long timescale (∼105 GM/c3), global, three dimensional magnetohydrodynamical accretion disk simulations with differing initial magnetic plasma β in order to study the effects of initial toroidal field strength on production of large-scale poloidal field. We initialize our disks in approximate equilibrium with purely toroidal magnetic fields of strength β0=5 and β0=200. We also perform a limited resolution study. We find that simulations of differing field strength diverge early in their evolution and remain distinct over the time studied, indicating that initial magnetic conditions leave a persistent imprint in our simulations. Neither simulation enters the Magnetically Arrested Disk (MAD) regime. Both simulations are able to produce poloidal fields from initially-toroidal fields, with the β0=5 simulation evolving clear signs of a large-scale poloidal field. We make a cautionary note that computational artifacts in the form of large-scale vortices may be introduced in the combination of initially-weak field and disk-internal mesh refinement boundaries, as evidenced by the production of an m=1 mode overdensity in the weak field simulation. Our results demonstrate that the initial toroidal field strength plays a vital role in simulated disk evolution for the models studied.