The Efficient Simulation of Complex Radiation Sources

Abstract

We describe the implementation and testing of the TREVR (Tree-based REVerse Ray-tracing) radiative transfer algorithm in the ChaNGa (Charm N-body Gravity solver) code. We calculated the optimal values for the source walk opening angle and ray trace walk refinement parameter of θ = 0.5 and τ = 0.01 respectively. We then studied the effects of the merging of sources on the accuracy of the calculated flux in absorbing regions, noting a systematic negative error and an angular dependence across all optical depths. We dubbed this the “Complex Sources Problem” and provide suggestions to mitigate its effects