Speaker
Description
The small-scale dynamics in magnetized accretion disks around rapidly rotating neutron stars is inherently coupled to the large-scale evolution of the disk through the action of a mean-field dynamo and turbulent stresses. The mean-field dynamo leads to the formation of coherent magnetic flux bundles that can migrate from the disk and power a collimated polar outflow as well as magnetic buoyancy-driven disk outflows. The small-scale turbulence, driven by the magnetorotational instability, sustains the mean-field dynamo and leads to disk spreading. The vast separation of scales between the turbulent plasma dynamics and the mean field disk evolution makes it challenging to work with resolutions that are high enough to fully resolve the former and an improved understanding of the coupling between the small- and large-scale dynamics is critical to understand how resolution-based effects can skew the simulated large-scale dynamics of post-merger systems. We present new diagnostics and a detailed analysis of the coupling between the small- and large-scale dynamics in the accretion disk around a rapidly rotating matter remnant from a binary neutron star merger. Our reference system is the post-merger remnant from an equal-mass binary, which we evolve with ideal general-relativistic magnetohydrodynamic, M0 radiation transport for neutrinos and a tabulated finite-temperature equation of state and without the use of any symmetries.