GiRaFFE: an open-source general relativistic force-free electrodynamics code

We present \newcommand{\GiR}{{\texttt{GiRaFFE}}} \GiR , the first open-source general relativistic force-free electrodynamics (GRFFE) code for dynamical, numerical-relativity generated spacetimes. \newcommand{\GiR}{{\texttt{GiRaFFE}}} \GiR adopts the strategy pioneered by McKinney (2006 Mon. Not. R. Astron. Soc. 367 1797) and modified by Paschalidis and Shapiro (2013 Phys. Rev. D 88 104031) to convert a GR magnetohydrodynamic (GRMHD) code into a GRFFE code. In short, \newcommand{\GiR}{{\texttt{GiRaFFE}}} \GiR exists as a modification of \newcommand{\IGM}{{\texttt{IllinoisGRMHD}}} \IGM (Etienne et al 2015 Class. Quantum Grav. 32 175009), a user-friendly, open-source, dynamical-spacetime GRMHD code. Both \newcommand{\GiR}{{\texttt{GiRaFFE}}} \GiR and \newcommand{\IGM}{{\texttt{IllinoisGRMHD}}} \IGM leverage the Einstein toolkit’s highly-scalable infrastructure to make possible large-scale simulations of magnetized plasmas in strong, dynamical spacetimes on adaptive-mesh refinement (AMR) grids. We demonstrate that \newcommand{\GiR}{{\texttt{GiRaFFE}}} \GiR passes a large suite of both flat and curved-spacetime code tests passed by a number of other state-of-the-art GRFFE codes, and is thus ready for production-scale simulations of GRFFE phenomena of key interest to relativistic astrophysics.