TREVR: A general $Nlo{g}^{2}N$ radiative transfer algorithm

Abstract

We present TREVR (Tree-based REVerse Ray Tracing), a general algorithm for computing the radiation field, including absorption, in astrophysical simulations. TREVR is designed to handle large numbers of sources and absorbers; it is based on a tree data structure and is thus suited to codes that use trees for their gravity or hydrodynamics solvers (e.g. Adaptive Mesh Refinement). It achieves computational speed while maintaining a specified accuracy via controlled lowering of the resolution of both sources and rays from each source. TREVR computes the radiation field in order $N\log N_{source}$ time without absorption and order $N\log N_{source}\log N$ time with absorption. These scalings arise from merging sources of radiation according to an opening angle criterion and walking the tree structure to trace a ray to a depth that gives the chosen accuracy for absorption. The absorption-depth refinement criterion is unique to TREVR. We provide a suite of tests demonstrating the algorithm's ability to accurately compute fluxes, ionization fronts and shadows.

15 pages, 15 figures and 1 table. Accepted by MNRAS

References in corpus (8)

• Cosmological Radiative Transfer Codes Comparison Project I: The Static Density Field Tests
• Driving Turbulence and Triggering Star Formation by Ionizing Radiation
• TRAPHIC - Radiative Transfer for Smoothed Particle Hydrodynamics Simulations
• An implementation of radiative transfer in the cosmological simulation code GADGET
• Tree-based solvers for adaptive mesh refinement code FLASH - I: gravity and optical depths
• SPHRAY: A Smoothed Particle Hydrodynamics Ray Tracer for Radiative Transfer
• Multi-frequency, thermally coupled radiative transfer with TRAPHIC: Method and tests
• Simulating radiative feedback and star cluster formation in GMCs: II. Mass dependence of cloud destruction and cluster properties