Large-scale relativistic simulations in the characteristic approach

We report on high-resolution computations in the characteristic approach to numerical relativity, using an extensible, highly scalable computational framework (LEO). A combination of a multi-bloc decomposition of the sphere (the ``cubed sphere''), with spin raising and lowering (``eth'') operators on non-conformal coordinates, and a first order reduction of the Einstein equations is used to obtain a stable, globally second-order accurate numerical method. Applying the framework to a scalar field minimally coupled to gravity in three dimensions, we extract quasi-normal modes, and notice the appearance of energy saturation effects. We analyze the scaling properties of the underlying framework and discuss possible extensions.