Galaxy And Mass Assembly (GAMA): The environmental impact on SFR and metallicity in galaxy groups

TL;DR

This study investigates how environment influences star formation rates and metallicity in galaxies within groups, revealing local density as a key factor affecting these properties, with some discrepancies between observations and simulations.

Contribution

It provides new insights into environmental effects on galaxy evolution, emphasizing local density over group-centric distance, and compares observational data with simulations from IllustrisTNG.

Findings

Highest SFR enhancement occurs in low-density environments.

Small SFR enhancements are observed at high densities and distances.

Stellar mass is the main driver of star formation quenching.

Abstract

We present a study of the relationships and environmental dependencies between stellar mass, star formation rate, and gas metallicity for more than 700 galaxies in groups up to redshift 0.35 from the Galaxy And Mass Assembly (GAMA) survey. To identify the main drivers, our sample was analyzed as a function of group-centric distance, projected galaxy number density, and stellar mass. By using control samples of more than 16000 star-forming field galaxies and volume limited samples, we find that the highest enhancement in SFR (0.3 dex) occurs in galaxies with the lowest local density. In contrast to previous work, our data show small enhancements of $\sim$0.1 dex in SFR for galaxies at the highest local densities or group-centric distances. Our data indicates quenching in SFR only for massive galaxies, suggesting that stellar mass might be the main driver of quenching processes for star forming galaxies. We can discard a morphological driven quenching, since the S\'ersic index distribution for group and control galaxies are similar. The gas metallicity does not vary drastically. It increases $\sim$0.08 dex for galaxies at the highest local densities, and decreases for galaxies at the highest group-centric distances, in agreement with previous work. Altogether, the local density, rather than group-centric distance, shows the stronger impact in enhancing both, the SFR and gas metallicity. We applied the same methodology to galaxies from the IllustrisTNG simulations, and although we were able to reproduce the general observational trends, the differences between group and control samples only partially agree with the observations