A radiative transfer scheme for cosmological reionization based on a local Eddington tensor

TL;DR

This paper introduces a new radiative transfer scheme for cosmological reionization using the M1 closure model, implemented in the ATON code, which is simple, robust, and compatible with grid-based solvers.

Contribution

The paper presents a novel radiative transfer scheme based on the M1 closure model, implemented in the ATON code, suitable for cosmological simulations.

Findings

Successfully reproduces standard test results such as HII region expansion

Accurately models radiation shielding by dense clumps

Demonstrates compatibility with cosmological fluid solvers

Abstract

A radiative transfer scheme is presented, based on a moment description of the equation of radiative transfer and the so-called ``M1 closure model'' for the Eddington tensor. This model features a strictly hyperbolic transport step for radiation: it has been implemented using standard Godunov--like techniques in a new code called ATON. Coupled to simple models of ionization chemistry and photo-heating, ATON is able to reproduce the results of other schemes on a various set of standard tests such as the expansion of a HII region, the shielding of the radiation by dense clumps and cosmological ionization by multiple sources. Being simple yet robust, such a scheme is intended to be naturally and easily included in grid--based cosmological fluid solvers.