SPRAI: Coupling of radiative feedback and primordial chemistry in moving mesh hydrodynamics

TL;DR

This paper presents SPRAI, a new radiative transfer code integrated into Arepo, enabling self-consistent simulation of ionizing radiation and primordial chemistry in astrophysical systems with multiple sources.

Contribution

The paper introduces SPRAI, a novel implementation of the SimpleX radiative transfer method within Arepo, allowing efficient, self-consistent modeling of radiation and chemistry in primordial gas.

Findings

Efficient coupling of radiative transfer with primordial chemistry.

Self-consistent modeling of ionization and chemical processes.

Suitable for systems with multiple ionizing sources.

Abstract

In this paper we introduce a new radiative transfer code SPRAI (Simplex Photon Radiation in the Arepo Implementation) based on the SimpleX radiation transfer method. This method, originally used only for post-processing, is now directly integrated into the Arepo code and takes advantage of its adaptive unstructured mesh. Radiated photons are transferred from the sources through the series of Voronoi gas cells within a specific solid angle. From the photon attenuation we derive corresponding photon fluxes and ionization rates and feed them to a primordial chemistry module. This gives us a self-consistent method for studying dynamical and chemical processes caused by ionizing sources in primordial gas. Since the computational cost of the SimpleX method does not scale directly with the number of sources, it is convenient for studying systems such as primordial star-forming halos that may form multiple ionizing sources.