A new radiative cooling curve based on an up to date plasma emission code

TL;DR

This paper introduces a new plasma radiative cooling curve based on the SPEX emission code, compares it with previous models, and integrates it into hydrodynamical simulations to improve accuracy in astrophysical plasma modeling.

Contribution

The work provides a novel cooling curve derived from the SPEX package, including element-specific contributions, and implements it in the AMRVAC framework for better plasma simulations.

Findings

Cooling rates are significantly higher above 10,000 K due to ionization.

The new cooling curve aligns well with previous models but offers element-specific customization.

Inclusion of radiative cooling affects the development of instabilities in simulations.

Abstract

This work presents a new plasma cooling curve that is calculated using the SPEX package. We compare our cooling rates to those in previous works, and implement the new cooling function in the grid-adaptive framework `AMRVAC'. Contributions to the cooling rate by the individual elements are given, to allow for the creation of cooling curves tailored to specific abundance requirements. In some situations, it is important to be able to include radiative losses in the hydrodynamics. The enhanced compression ratio can trigger instabilities (such as the Vishniac thin-shell instability) that would otherwise be absent. For gas with temperatures below 10,000 K, the cooling time becomes very long and does not affect the gas on the timescales that are generally of interest for hydrodynamical simulations of circumstellar plasmas. However, above this temperature, a significant fraction of the elements is ionised, and the cooling rate increases by a factor 1000 relative to lower temperature plasmas.