Toward General-Relativistic Magnetohydrodynamics Simulations in Stationary Non-Vacuum Spacetimes

Understand

Accretion of magnetized gas on compact astrophysical objects such as black holes has been successfully modeled using general relativistic magnetohydrodynamic (GRMHD) simulations.

• These simulations have largely been performed in the Kerr metric, which describes the spacetime of a vacuum and stationary spinning black hole (BH) in general relativity (GR).
• The simulations have revealed important clues on the physics of accretion and jets near the BH event horizon, and have been used to interpret recent Event Horizon Telescope images of the supermassive BHs, M87$^*$ and Sgr A$^*$.
• GRMHD simulations require the spacetime metric in horizon-penetrating coordinates such that all metric coefficients are regular at the event horizon.