Detection of metallicity correlations in 100 nearby galaxies

TL;DR

This study analyzes metallicity fluctuations in 100 nearby galaxies, revealing significant correlations at ~1 kpc scales, which vary with galaxy mass and star formation, offering insights into galaxy evolution processes.

Contribution

It introduces a method to measure 2D metallicity correlations in galaxies and demonstrates their dependence on galaxy properties, advancing understanding of metal mixing and galaxy evolution.

Findings

Correlations are detected in most galaxies, exceeding beam-smearing effects.

Correlation lengths are approximately 1 kpc and increase with stellar mass and star formation rate.

No significant correlation with Hubble type, barredness, or merging state.

Abstract

In this paper we analyse the statistics of the 2D gas-phase oxygen abundance distributions of 100 nearby galaxies drawn from the Calar Alto Legacy Integral Field spectroscopy Area survey. After removing the large-scale radial metallicity gradient, we compute the two-point correlation functions of the resulting metallicity fluctuation maps. We detect correlations in the majority of our targets, which we show are significantly in excess of what is expected due to beam-smearing, and are robust against the choice of metallicity diagnostic. We show that the correlation functions are generally well-fit by the predictions of a simple model for stochastic metal injection coupled with diffusion, and from the model we show that, after accounting for the effects of both beam smearing and noise, the galaxies in our sample have characteristic correlation lengths of $\sim1$ kpc. Correlation lengths increase with both stellar mass and star formation rate, but show no significant variation with Hubble type, barredness, or merging state. We also find no evidence for a theoretically-predicted relationship between gas velocity dispersion and correlation length, though this may be due to the small dynamic range in gas velocity dispersion across our sample. Our results suggest that measurements of 2D metallicity correlation functions can be a powerful tool for studying galaxy evolution.