Simulating radiative astrophysical flows with the PLUTO code: A non-equilibrium, multi-species cooling function

TL;DR

This paper introduces a set of tools for simulating radiative astrophysical flows with non-equilibrium, multi-species cooling functions, improving the accuracy of emission predictions in shocked plasma environments.

Contribution

It provides a detailed implementation of a non-equilibrium cooling model with a 29-ion species network for astrophysical MHD simulations.

Findings

Cooling model significantly affects flow morphology.

Validated the model against astrophysical shock scenarios.

Enhanced prediction accuracy for emission line ratios.

Abstract

Time-dependent cooling processes are of paramount importance in the evolution of astrophysical gaseous nebulae and, in particular, when radiative shocks are present. The present work introduces a necessary set of tools that can be used to model radiative astrophysical flows in the optically-thin plasma limit. We aim to provide reliable and accurate predictions of emission line ratios and radiative cooling losses in astrophysical simulations of shocked flows. Moreover, we discuss numerical implementation aspects to ease future improvements and implementation in other MHD numerical codes. The most important source of radiative cooling for our plasma conditions comes from the collisionally-excited line radiation. We evolve a chemical network, including 29 ion species, to compute the ionization balance in non-equilibrium conditions. After a series of validations and tests, typical astrophysical setups are simulated in 1D and 2D, employing both the present cooling model and a simplified one. The influence of the cooling model on structure morphologies can become important, especially for emission line diagnostic purposes.