Physics
Friedrich-Schiller-Universität Jena
Theoretisch-Physikalisches Institut
We seek to complete scaling tests for a new numerical relativity code for binary neutron star (BNS) simulations, GR-Athena++, in preparation for production simulations. The calculation of gravitational waves and other observables from BNSs requires exascale HPC to resolve MHD instabilities and to attain sufficient resolution for quantitative predictions of the radiation in the wave zone. Building on the Athena++ framework, we have developed a code that scales to over 10,000 cores for the binary black hole problem. We have now implemented general-relativistic MHD for the evolution of neutron star spacetimes and show preliminary scaling tests in-line with the vacuum case. This code builds on an efficient octree based mesh-refinement and incorporates a constrained-transport scheme and a new equation of state interface able to handle microphysical matter models. These scaling tests will allow us to design production runs for high-resolution simulations of MHD instabilities in BNS mergers.