Ion-by-ion Cooling efficiencies

TL;DR

This paper provides detailed ion-by-ion cooling efficiencies for low-density gases across a wide temperature range, enabling more accurate modeling of astrophysical cooling processes especially under non-equilibrium conditions.

Contribution

It introduces comprehensive ion-specific cooling efficiencies for 30 elements using Cloudy, including non-equilibrium ionization effects, with results available in online tables.

Findings

Ion-by-ion cooling efficiencies for 30 elements are provided.

Results cover temperatures from 10^4 to 10^8 K.

Online tables facilitate easy access and application.

Abstract

We present ion-by-ion cooling efficiencies for low-density gas. We use Cloudy (ver. 08.00) to estimate the cooling efficiencies for each ion of the first 30 elements (H-Zn) individually. We present results for gas temperatures between 1e4 and 1e8K, assuming low densities and optically thin conditions. When nonequilibrium ionization plays a significant role the ionization states deviate from those that obtain in collisional ionization equilibrium (CIE), and the local cooling efficiency at any given temperature depends on specific non-equilibrium ion fractions. The results presented here allow for an efficient estimate of the total cooling efficiency for any ionic composition. We also list the elemental cooling efficiencies assuming CIE conditions. These can be used to construct CIE cooling efficiencies for non-solar abundance ratios, or to estimate the cooling due to elements not explicitly included in any nonequilibrium computation. All the computational results are listed in convenient online tables.