Hyperbolic self-gravity solver for large scale hydrodynamical simulations

A new computationally efficient method has been introduced to treat self-gravity in Eulerian hydrodynamical simulations. It is applied simply by modifying the Poisson equation into an inhomogeneous wave equation. This roughly corresponds to the weak field limit of the Einstein equations in general relativity, and as long as the gravitation propagation speed is taken to be larger than the hydrodynamical characteristic speed, the results agree with solutions for the Poisson equation. The solutions almost perfectly agree if the domain is taken large enough, or appropriate boundary conditions are given. Our new method cannot only significantly reduce the computational time compared with existent methods, but is also fully compatible with massive parallel computation, nested grids, and adaptive mesh refinement techniques, all of which can accelerate the progress in computational astrophysics and cosmology.