Fervent: Chemistry-coupled, ionising and non-ionising radiative feedback in magnetohydrodynamical simulations

TL;DR

This paper presents Fervent, a new radiative transfer module for MHD simulations that models stellar feedback effects on the interstellar medium with detailed chemistry and thermal processes, validated against PDR codes.

Contribution

Introduction of Fervent, a radiative transfer module integrated with FLASH 4, capable of simulating thermal and chemical feedback from massive stars with detailed physics and validation.

Findings

Good agreement with PDR codes in hydrogen species modeling.

Radiative feedback physics is resolution-insensitive.

Module effectively models combined ionizing and non-ionizing radiation.

Abstract

We introduce a radiative transfer code module for the magnetohydrodynamical adaptive mesh refinement code FLASH 4. It is coupled to an efficient chemical network which explicitly tracks the three hydrogen species H, H_2, H+ as well as C+ and CO. The module is geared towards modeling all relevant thermal feedback processes of massive stars, and is able to follow the non-equilibrium time-dependent thermal and chemical state of the present-day interstellar medium as well as that of dense molecular clouds. We describe in detail the implementation of all relevant thermal stellar feedback mechanisms, i.e. photoelectric, photoionization and H_2 dissociation heating as well as pumping of molecular hydrogen by UV photons. All included radiative feedback processes are extensively tested. We also compare our module to dedicated photon-dominated region (PDR) codes and find good agreement in our modeled hydrogen species once our radiative transfer solution reaches equilibrium. In addition, we show that the implemented radiative feedback physics is insensitive to the spatial resolution of the code and show under which conditions it is possible to obtain well-converged evolution in time. Finally, we briefly explore the robustness of our scheme for treating combined ionizing and non-ionizing radiation.