The Numerical Methods We Used to Study Black Holes

Our numerical scheme utilizes the GRMHD code KHARMA[1], a performance-portable C++ implementation based on iharm3D (Prather et al. 2021); iharm3D is itself an extension of HARM, an efficient secondorder conservative finite-volume scheme for solving MHD equations on Eulerian meshes in stationary curved space-times (Gammie et al. 2003). KHARMA offers a more flexible, portable, and scalable implementation suitable for multiple uses, by leveraging the Parthenon Adaptive Mesh Refinement Framework and the Kokkos programming model (Grete et al. 2023; Trott et al. 2022).