The Monte Carlo photoionization and moving-mesh radiation hydrodynamics code CMacIonize

TL;DR

CMacIonize is a versatile Monte Carlo-based code for simulating the evolution of ionized regions around stars, combining radiation transfer and hydrodynamics in a grid-independent framework.

Contribution

It introduces a new public code that integrates Monte Carlo photoionization with moving-mesh radiation hydrodynamics for self-consistent astrophysical simulations.

Findings

Enables self-consistent evolution of HII regions around stars.

Supports both post-processing and full radiation hydrodynamics simulations.

Flexible grid structure implementation.

Abstract

We present the public Monte Carlo photoionization and moving-mesh radiation hydrodynamics code CMacIonize, which can be used to simulate the self-consistent evolution of HII regions surrounding young O and B stars, or other sources of ionizing radiation. The code combines a Monte Carlo photoionization algorithm that uses a complex mix of hydrogen, helium and several coolants in order to self-consistently solve for the ionization and temperature balance at any given type, with a standard first order hydrodynamics scheme. The code can be run as a post-processing tool to get the line emission from an existing simulation snapshot, but can also be used to run full radiation hydrodynamical simulations. Both the radiation transfer and the hydrodynamics are implemented in a general way that is independent of the grid structure that is used to discretize the system, allowing it to be run both as a standard fixed grid code, but also as a moving-mesh code.