The Lagrangian Numerical Relativity code SPHINCS_BSSN_v1.0

Understand

We present version 1.0 of our Lagrangian Numerical Relativity code SPHINCS_BSSN.

• This code evolves the full set of Einstein equations, but contrary to other Numerical Relativity codes, it evolves the matter fluid via Lagrangian particles in the framework of a high-accuracy version of Smooth Particle Hydrodynamics (SPH).
• The major new elements introduced here are: i) a new method to map the stress--energy tensor (known at the particles) to the spacetime mesh, based on a local regression estimate; ii) additional measures that ensure the robust evolution of a neutron star through its collapse to a black hole; and iii) further refinements in how we place the SPH particles for our initial data.
• The latter are implemented in our code SPHINCS_ID which now, in addition to LORENE, can also couple to initial data produced by the initial data library FUKA.