Star formation and chemical enrichment in protoclusters
Keita Fukushima, Kentaro Nagamine, Ikkoh Shimizu
Abstract
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 ($\gt 10^{14.4}\, h^{-1}$ M⊙) reaches $\gt 10^4\, \mathrm{M}_\odot \mathrm{yr}^{-1}$ at z = 3, equivalent to the observed PCs. The SFR in the Core region accounts for about 30 per cent of the total star formation in the PC at z ≳ 1, 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 stellar masses $10^{10}\, \le \, (\mathrm{M}_\star /{{\rm M}_{\odot }})\, \le \, 10^{11}$, 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] versus [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) versus 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.