Metallicity determination in gas-rich galaxies with semiempirical methods

TL;DR

This paper evaluates the accuracy of semiempirical methods for determining chemical abundances in gas-rich galaxies, finding that different methods perform best in specific metallicity regions and that all methods show some insensitivity to metallicity variations.

Contribution

It introduces a new calibration of the P method that reduces dispersion and compares multiple semiempirical methods across a large galaxy sample.

Findings

The new P method calibration yields smaller dispersion in abundance estimates.

The R23 method performs best in the turnaround metallicity region.

All methods show insensitivity to metallicity for over half the sample.

Abstract

A study of the precision of the semiempirical methods used in the determination of the chemical abundances in gas-rich galaxies is carried out. In order to do this the oxygen abundances of a total of 438 galaxies were determined using the electronic temperature, the $R_{23}$ and the P methods. The new calibration of the P method gives the smaller dispersion for the low and high metallicity regions, while the best numbers in the turnaround region are given by the $R_{23}$ method. We also found that the dispersion correlates with the metallicity. Finally, it can be said that all the semiempirical methods studied here are quite insensitive to metallicity with a value of $8.0\pm0.2$ dex for more than 50% of the total sample. \keywords{ISM: abundances; (ISM): H {\sc ii} regions}