• DOI:10.1093/mnras/stt2175
• Corpus ID: 119257675

The dependence of the galaxy mass-metallicity relation on environment and the implied metallicity of the IGM

@article{Peng2013TheDO,
  title={The dependence of the galaxy mass-metallicity relation on environment and the implied metallicity of the IGM},
  author={Yingjie Peng and Roberto Maiolino},
  journal={Monthly Notices of the Royal Astronomical Society},
  year={2013},
  volume={438},
  pages={262-270}
}

• Yingjie Peng, R. Maiolino
• Published 7 November 2013
• Physics
• Monthly Notices of the Royal Astronomical Society

We explore the dependence of the galaxy mass-metallicity relation on environment in SDSS, in terms of both over-density and central/satellite dichotomy. We find that at a given stellar mass, there is a strong dependence of metallicity on over-density for star-forming satellites. Instead, for star-forming centrals no correlation is found. Star-forming satellites at different stellar masses form a tight sequence in the average overdensity - metallicity plane, which covers the entire observed range of metallicities and stellar masses. This remarkable result appears to imply that there exists a universal evolutionary path for all star-forming satellites, regardless of their stellar masses. The strong correlation between over-density and metallicity for star-forming satellites indicates that the gas inflow of satellite galaxies is progressively metal-enriched in denser regions. We interpret our results by employing the gas regulator model and find that the metallicity of the enriched inflow of star-forming satellite galaxies strongly increases with increasing over-density, largely independently of stellar mass. If the metallicity of the inflow of star-forming satellites can represent the metallicity of the IGM, then the implied metallicity of the IGM rises from ~ 0.01 solar metallicity in void-like environments to ~ 0.3 solar metallicity in cluster-like environments, in broad agreement with observations. We show that the observed metallicity difference between star-forming centrals and star-forming satellites becoming smaller towards high stellar masses can be simply explained by the mass-independent enriched inflow, without the need to involve any mass-dependent environmental effect on metallicity. Since satellite galaxies account for at least half of the galaxy population, our findings prompt for a revision of many galaxy evolutionary models, which generally assume pristine gas inflows.