# pyqz 0.8.4¶

The pyqz Python module computes the values of log(Q) [the ionization parameter] and 12+log(O/H) [the oxygen abundance, either total or in the gas phase] for a given set of strong emission lines fluxes from HII regions.

The log(Q) and 12+log(O/H) values are interpolated from a finite set of diagnostic line ratio grids computed with the MAPPINGS code. The grids used by pyqz are chosen to be flat, without wraps, to decouple the influence of log(Q) and 12+log(O/H) on the emission line ratios.

pyqz 0.4 was the first publicly released version of the code, which is described in detail in

Dopita et al., New Strong Line Abundance Diagnostics for HII Regions: Effects of Updated Atomic Data and kappa-Distributed Electron Energies, ApJS, 208, 10 (2013). ADS entry

pyqz has since been subject to a major overhaul to track the latest heroic developments in the MAPPINGS code, support the propagation of observational errors, auto-detect wraps in the diagnostics grids, and more.

The current photo-ionization models shipped with pyz were generated using MAPPINGS 5.0.16. At this time the safe ranges of the models are:

$\begin{split}6.5\ \leq\ \mathrm{LogQ}\ \leq\ 8.5\\ 8.11\ \leq\ \mathrm{Tot[O]+12}\ \leq\ 8.985\\ \kappa\ =\ \infty\end{split}$

Generating MAPPINGS models outside this zone is currently unsafe, and thus will remain unsupported by pyqz until further updates to the MAPPINGS code.

Note

You can track the latest changes in the code in the Changelog or on the dedicated Github repository.

Warning

Garbage in, garbage out !

Simplicity and ease of use are important design drivers for pyqz. These (hopefully!) imply an easy-to-run code, where all parameters are accessible but most come with a default setting.

But be aware that the default settings will not be optimum for everyone. Before you use pyqz, read carefully the Understanding pyqz section, or chances are, you will be deriving wrong estimates of 12+log(O/H) and log(Q)! No one wants this to happen.