SPHINCS_BSSN: A general relativistic Smooth Particle Hydrodynamics code for dynamical spacetimes

Understand

We present a new methodology for simulating self-gravitating general-relativistic fluids.

• In our approach the fluid is modelled by means of Lagrangian particles in the framework of a general-relativistic (GR) Smooth Particle Hydrodynamics (SPH) formulation, while the spacetime is evolved on a mesh according to the BSSN formulation that is also frequently used in Eulerian GR-hydrodynamics.
• To the best of our knowledge this is the first Lagrangian fully general relativistic hydrodynamics code (all previous SPH approaches used approximations to GR-gravity).
• A core ingredient of our particle-mesh approach is the coupling between the gas (represented by particles) and the spacetime (represented by a mesh) for which we have developed a set of sophisticated interpolation tools that are inspired by other particle-mesh approaches, in particular by vortex-particle methods.