The metal enrichment of passive galaxies in cosmological simulations of galaxy formation

Abstract

Massive early-type galaxies have higher metallicities and higher ratios of $\alpha$ elements to iron than their less massive counterparts. Reproducing these correlations has long been a problem for hierarchical galaxy formation theory, both in semi-analytic models and cosmological hydrodynamic simulations. We show that a simulation in which gas cooling in massive dark haloes is quenched by radio-mode active galactic nuclei (AGNs) feedback naturally reproduces the observed trend between $\alpha$/Fe and the velocity dispersion of galaxies, $\sigma$. The quenching occurs earlier for more massive galaxies. Consequently, these galaxies complete their star formation before $\alpha$/Fe is diluted by the contribution from type Ia supernovae. For galaxies more massive than $\sim 10^{11}{M}_{\odot }$ whose $\alpha$/Fe correlates positively with stellar mass, we find an inversely correlated mass-metallicity relation. This is a common problem in simulations in which star formation in massive galaxies is quenched either by quasar- or radio-mode AGN feedback. The early suppression of gas cooling in progenitors of massive galaxies prevents them from recapturing enriched gas ejected as winds. Simultaneously reproducing the [$\alpha$/Fe]-$\sigma$ relation and the mass-metallicity relation is, thus, difficult in the current framework of galaxy formation.

10 pages, 5 figures, accepted for publication in MNRAS, added references

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Cited by in corpus (11)

• L-GALAXIES 2020: Spatially resolved cold gas phases, star formation and chemical enrichment in galactic discs
• L-GALAXIES 2020: The evolution of radial metallicity profiles and global metallicities in disc galaxies
• Astraeus V: The emergence and evolution of metallicity scaling relations during the Epoch of Reionization
• Mass-Metallicity and Star Formation Rate in Galaxies: a complex relation tuned to stellar age
• Resolved Multi-element Stellar Chemical Abundances in the Brightest Quiescent Galaxy at z $\sim$ 2
• AGN feedback and the origin of the $\alpha$ enhancement in early type galaxies - insights from the GAEA model
• The star formation history and the nature of the mass-metallicity relation of passive galaxies at 1.0<z<1.4 from VANDELS
• SDSS-IV MaNGA: The [$\alpha$/Fe] of Early-Type Galaxies
• Cloud-cloud collisions triggering star formation in galaxy simulations
• The star formation timescale of elliptical galaxies -- Fitting [Mg/Fe] and total metallicity simultaneously
• Downsizing revised: Star formation timescales for elliptical galaxies with an environment-dependent IMF and number of SNIa