Dynamics and metallicity of far-infrared selected galaxies

We present near-infrared integral field spectroscopy of 10 Herschel selected galaxies at z similar to 1.5. From detailed mapping of the H alpha and [N II] 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 (spectral energy distribution) 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 intergalactic medium (IGM) in dense environments, and therefore suggests that here the IGM was already significantly enriched by z similar to 1.5.