One main goal of this Ph.D. project at the University of Valencia (supervised by Prof. M. A. Aloy, CAMAP – Computer Aided Modeling of Astrophysical Plasmas) is the study of conditions leading to an efficient jet launching around (rapidly) rotating Kerr black holes. An initial focus of the project was the search for suitable electromagnetic field configurations in the vicinity of black holes (also known as the magnetosphere) as solutions to the so-called relativistic Grad-Shafranov equation. For this purpose, a numerical solver for the relativistic Grad-Shafranov equation was implemented and tested - we were able to analyze and improve the numerical techniques used to solve the relativistic Grad-Shafranov equation across its singular surfaces and provide a detailed review of convergence properties. Recent developments in the numerical simulation of black holes and their relativistic outflows underline the need for both reliable initial data, and evolution procedures for highly scalable 3D simulations. In the framework of the Einstein Toolkit, an evolution thorn for force-free electrodynamics has been implemented and is currently undergoing first test stages.
The implementation of the numerical Grad-Shafranov solver has been done in Fortran and relies on OpenMP parallelization as well as the computational architecture of the CoCoNuT code. The EinsteinToolkit (C/C++/Fortran) is a highly scalable, open-source environment for numerical General Relativity and relies on both OpenMP, and MPI parallelization. Recent development efforts include, e.g., its extension to GPU resources as well as adaptive mesh refinement on MPI framed grids.