Radiation Hydrodynamics using Characteristics on Adaptive Decomposed Domains for Massively Parallel Star Formation Simulations

TL;DR

This paper introduces a parallel, adaptive mesh-based radiative transfer algorithm using characteristics, enabling detailed star formation simulations with accurate radiation physics across different optical regimes.

Contribution

It develops a novel adaptive raytracer integrated into a parallel MHD framework, improving radiation modeling in star formation simulations.

Findings

Accurate results in standard radiative transfer tests.

Successful 3D collapse simulations of protostar and disc formation.

Efficient handling of optically thin and thick regimes.

Abstract

We present an algorithm for solving the radiative transfer problem on massively parallel computers using adaptive mesh refinement and domain decomposition. The solver is based on the method of characteristics which requires an adaptive raytracer that integrates the equation of radiative transfer. The radiation field is split into local and global components which are handled separately to overcome the non-locality problem. The solver is implemented in the framework of the magneto-hydrodynamics code FLASH and is coupled by an operator splitting step. The goal is the study of radiation in the context of star formation simulations with a focus on early disc formation and evolution. This requires a proper treatment of radiation physics that covers both the optically thin as well as the optically thick regimes and the transition region in particular. We successfully show the accuracy and feasibility of our method in a series of standard radiative transfer problems and two 3D collapse simulations resembling the early stages of protostar and disc formation.