Oral Presentation
Environmental dependence of chemical evolution in protoclusters and the transition of the mass assembly phase
Presenter: Kota Adachi (Tohoku University)
Chemical evolution of galaxies is regulated by not only past star formation activities but also gas inflow from surrounding large-scale structures and outflow from galaxies back to the halos driven by AGN or SNe. Such gaseous processes may well depend on the surrounding environments, especially in clusters, because of inefficient gas accretion and enhanced gas stripping. Past simulation imply that the vigorous mass assembly and transition of gas accretion phase occurs at cosmic noon. However, the details of how the gas flows actually work are still under debate, and it is also hard to observationally quantify them.
In this presentation, we report on our Keck/MOSFIRE spectroscopy of Ha emitters in XCS2215 cluster (z=1.5). The measurements of gas-phase metallicity and chemical evolution modeling reveal that they have higher metallicities and weaker outflow rates compared to field counterparts at similar redshift. The metallicity enhancement observed in this hot-mode cluster is likely caused by the lack of metallicity dilution due to inefficient gas accretion, along with the confinement of metal-enriched outflow due to the high pressure of ICM, leading to further chemical enrichment via recycling the gas.
Compared with other clusters around z=2, XCS2215 galaxies are more enriched especially in low-mass regime, implying the downsizing scenario. We will also present metallicities measured with JWST/NIRSpec for galaxies in other overdensities at z ~ 3.4, including large-scale filament called Cosmic Vine. These results allow us to investigate metallicities across different environments and redshifts and to explore the transition of mass assembly phase.
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