A general hybrid radiation transport scheme for star formation simulations on an adaptive grid

TL;DR

This paper introduces a hybrid radiation transport scheme combining raytracing and flux-limited diffusion within an adaptive grid code, enabling accurate and efficient simulations of radiation feedback in star formation environments.

Contribution

The authors develop and implement a hybrid radiation transfer method in the FLASH code, improving simulation accuracy for star formation studies involving complex geometries and multiple sources.

Findings

Accurately models irradiation of disks and shocks.

Capable of casting shadows and computing temperatures with multiple sources.

Validated through benchmark tests showing high accuracy.

Abstract

Radiation feedback plays a crucial role in the process of star formation. In order to simulate the thermodynamic evolution of disks, filaments, and the molecular gas surrounding clusters of young stars, we require an efficient and accurate method for solving the radiation transfer problem. We describe the implementation of a hybrid radiation transport scheme in the adaptive grid-based FLASH general magnetohydrodynamics code. The hybrid scheme splits the radiative transport problem into a raytracing step and a diffusion step. The raytracer captures the first absorption event, as stars irradiate their environments, while the evolution of the diffuse component of the radiation field is handled by a flux-limited diffusion (FLD) solver. We demonstrate the accuracy of our method through a variety of benchmark tests including the irradiation of a static disk, subcritical and supercritical radiative shocks, and thermal energy equilibration. We also demonstrate the capability of our method for casting shadows and calculating gas and dust temperatures in the presence of multiple stellar sources. Our method enables radiation-hydrodynamic studies of young stellar objects, protostellar disks, and clustered star formation in magnetized, filamentary environments.