The MOSDEF Survey: Environmental dependence of the gas-phase metallicity of galaxies at 1.4≤ z ≤2.6
Department of Physics and Astronomy, University of California at Riverside
Abstract: Using the near-IR spectroscopy of the MOSFIRE Deep Evolution Field (MOSDEF) survey, we investigate the role of the local environment in the gas-phase metallicity of galaxies. The local environment measurements are derived from accurate and uniformly calculated photometric redshifts with well-calibrated probability distributions. Based on rest-frame optical emission lines, [NII]λ6584 and Hα, we measure gas-phase oxygen abundance of 167 galaxies at 1.37≤z≤1.7 and 303 galaxies at 2.09≤z≤2.61, located in diverse environments. We find that at z∼1.5, the average metallicity of galaxies in overdensities with M∗∼10^ 9.8 M⊙,10^10.2 M⊙ and 10^10.8 M⊙ is higher relative to their field counterparts by 0.094±0.051, 0.068±0.028 and 0.052±0.043 dex, respectively.
However, this metallicity enhancement does not exist at higher redshift, z∼2.3, where, compared to the field galaxies, we find 0.056±0.043, 0.056±0.028 and 0.096±0.034 dex lower metallicity for galaxies in overdense environments with M∗∼10^9.8M⊙,10^10.2 M⊙ and 10^10.7 M⊙, respectively. Our results suggest that, at 1.37≤ z ≤2.61, the variation of mass-metallicity relation with the local environment is small (<0.1dex), and reverses at z∼2. Our results support the hypothesis that, at the early stages of cluster formation, owing to efficient gas cooling, galaxies residing in overdensities host a higher fraction of pristine gas with prominent primordial gas accretion, which lowers their gas-phase metallicity compared to their coeval field galaxies. However, as the Universe evolves to lower redshifts (z≲2), shock-heated gas in overdensities cannot cool down efficiently, and galaxies become metal-rich rapidly due to the suppression of pristine gas inflow and re-accretion of metal-enriched outflows in overdensities.
یکشنبه 21 دی 1399، ساعت 19:00
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