Star Formation and Chemical Enrichment in Protoclusters

TL;DR

This study uses cosmological simulations to analyze star formation and chemical enrichment in protoclusters, revealing the significance of outer regions, galaxy mass influences, and rapid early chemical evolution.

Contribution

It provides new insights into the spatial and mass-dependent star formation and chemical enrichment processes in protoclusters at high redshift.

Findings

Total SFR in protoclusters exceeds 10^4 M_sun/yr at z=3

Outer regions contribute about 30% to total star formation

Chemical enrichment proceeds faster at high redshift in dense environments

Abstract

We examine star formation and chemical enrichment in protoclusters (PCs) using cosmological zoom-in hydrodynamic simulations. We find that the total star formation rate (SFR) in all PC ($>10^{14.4}\,h^{-1}$M$_\odot$) reaches $>10^4\,\mathrm{M}_\odot \mathrm{yr}^{-1}$ at $z=3$, equivalent to the observed PCs. The SFR in the Core region accounts for about $30\%$ of the total star formation in the PC at $z\gtrsim1$, suggesting the importance of the outer regions to reveal the evolution of galaxy clusters. We find that the total SFR of PC is dominated by galaxies with $10^{10}\,\le\,(\mathrm{M}_\star/M_\odot)\,\le\,10^{11}$, while more massive galaxies dominate the SFR in the Core. For the chemical abundance evolution, we find that the higher-density region has a higher metallicity and faster evolution. We show that the [O/Fe] vs. [Fe/H] relation turns down in the Core at $z=3.4$ due to the enrichment of Fe by Type Ia supernovae. We find no environmental effects for the mass--metallicity relations (MZR) or $\log$(N/O) vs. $12+\log$(O/H) for galaxies. We find that the chemical enrichment in galaxy clusters proceeds faster in the high redshift Universe ($z>1$). Our work will benefit future tomographic observations, particularly using PCs as unique probes of accelerated structure formation and evolution in high-density regions of the universe.