The Absence of an Environmental Dependence in the Mass-Metallicity Relation at z=2

TL;DR

This study finds no significant environmental dependence of the mass-metallicity relation at z=2, indicating that galaxy environment has minimal impact compared to internal processes like inflow and outflow.

Contribution

It provides the first observational evidence showing no discernible difference in the mass-metallicity relation between field and cluster galaxies at z=2.

Findings

No difference in mass-metallicity relation between field and cluster galaxies within 0.02dex.

Both observed and simulated relations are consistent, with minor offsets.

Environmental effects are secondary to internal galaxy processes at this epoch.

Abstract

We investigate the environmental dependence of the mass-metallicity relation at z=2 with MOSFIRE/Keck as part of the ZFIRE survey. Here, we present the chemical abundance of a Virgo-like progenitor at z=2.095 that has an established red sequence. We identified 43 cluster ($<z>=2.095\pm0.004$) and 74 field galaxies ($<z>=2.195\pm0.083$) for which we can measure metallicities. For the first time, we show that there is no discernible difference between the mass-metallicity relation of field and cluster galaxies to within 0.02dex. Both our field and cluster galaxy mass-metallicity relations are consistent with recent field galaxy studies at z~2. We present hydrodynamical simulations for which we derive mass-metallicity relations for field and cluster galaxies. We find at most a 0.1dex offset towards more metal-rich simulated cluster galaxies. Our results from both simulations and observations are suggestive that environmental effects, if present, are small and are secondary to the ongoing inflow and outflow processes that are governed by galaxy halo mass.