Publication details for Prof Carlos FrenkOkamoto, T., Nagashima, M., Lacey, C. G. & Frenk, C. S. (2017). The metal enrichment of passive galaxies in cosmological simulations of galaxy formation. Monthly Notices of the Royal Astronomical Society 464(4): 4866-4874.
- Publication type: Journal Article
- ISSN/ISBN: 0035-8711, 1365-2966
- DOI: 10.1093/mnras/stw2729
- Further publication details on publisher web site
- Durham Research Online (DRO) - may include full text
Author(s) from Durham
Massive early-type galaxies have higher metallicities and higher ratios of α 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 α/Fe and the velocity dispersion of galaxies, σ. The quenching occurs earlier for more massive galaxies. Consequently, these galaxies complete their star formation before α/Fe is diluted by the contribution from Type Ia supernovae. For galaxies more massive than ∼1011 M⊙, whose α/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 [α/Fe]–σ relation and the mass–metallicity relation is, thus, difficult in the current framework of galaxy formation.