Dynamics and Metallicity of Far-IR Selected Galaxies

TL;DR

This study uses near-infrared integral field spectroscopy to analyze the dynamics, star formation, and metallicity of ten Herschel-selected galaxies at z~1.5, revealing complex gas distributions and environmental effects on metallicity.

Contribution

It provides detailed spatially-resolved measurements of galaxy properties at z~1.5, highlighting the impact of minor mergers and environment on metallicity and star formation.

Findings

Most galaxies follow the fundamental metallicity relation with large scatter.

Star formation traced by Hα often differs from UV emission, indicating complex star formation regions.

One galaxy deviates from the FMR, supporting environmental enrichment effects at high redshift.

Abstract

We present near-infrared integral field spectroscopy of ten Herschel selected galaxies at z~1.5. From detailed mapping of the H$\alpha$ and [NII] emission lines we trace the dynamics, star formation rates, metallicities and also investigate gas fractions for these galaxies. For a few galaxies the distribution of star formation as traced by H$\alpha$ only traces a small fraction of the stellar disc, which could be tracing recent minor merging events. The rest-frame ultraviolet (UV) continuum emission often has a distribution completely different from H$\alpha$, which warns about the use of UV-SED based star formation tracers in these systems. Our analysis of galaxy dynamics shows that minor dynamical disruptions (e.g. minor merging) are generally not enough to cause a deviation from the established 'Main Sequence' relation. Most galaxies are found to follow the fundamental metallicity relation (FMR), although with large scatter. One galaxy, (a small satellite galaxy of a massive companion) is found to deviate strongly from the FMR. This deviation is in nice agreement with the correlation recently discovered in local galaxies between gas metallicity and environment, which has been ascribed to enriched inter-galactic medium (IGM) in dense environments, and therefore suggests that here the IGM was already significantly enriched by z~1.5.