The E-MOSAICS project: tracing galaxy formation and assembly with the age-metallicity distribution of globular clusters

Abstract

We present 25 cosmological zoom-in simulations of Milky Way-mass galaxies in the `MOdelling Star cluster population Assembly In Cosmological Simulations within EAGLE' (E-MOSAICS) project. E-MOSAICS couples a detailed physical model for the formation, evolution, and disruption of star clusters to the EAGLE galaxy formation simulations. This enables following the co-formation and co-evolution of galaxies and their star cluster populations, thus realising the long-standing promise of using globular clusters (GCs) as tracers of galaxy formation and assembly. The simulations show that the age-metallicity distributions of GC populations exhibit strong galaxy-to-galaxy variations, resulting from differences in their evolutionary histories. We develop a formalism for systematically constraining the assembly histories of galaxies using GC age-metallicity distributions. These distributions are characterised through 13 metrics that we correlate with 30 quantities describing galaxy formation and assembly (e.g. halo properties, formation/assembly redshifts, stellar mass assembly time-scales, galaxy merger statistics), resulting in 20 statistically (highly) significant correlations. The GC age-metallicity distribution is a sensitive probe of the mass growth, metal enrichment, and minor merger history of the host galaxy. No such relation is found between GCs and major mergers, which play a sub-dominant role in GC formation for Milky Way-mass galaxies. Finally, we show how the GC age-metallicity distribution enables the reconstruction of the host galaxy's merger tree, allowing us to identify all progenitors with masses $M_{\ast }\gtrsim 10^8$ M${}_{\odot }$ for redshifts $1\le z\le 2.5$. These results demonstrate that cosmological simulations of the co-formation and co-evolution of GCs and their host galaxies successfully unlock the potential of GCs as quantitative tracers of galaxy formation and assembly.

44 pages (including appendices), 13 figures, 14 tables; accepted by MNRAS (April 2, 2019). Figures 3, 8, 10, and 11 show the main results of the paper

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Cited by in corpus (14)

• Star clusters near and far; tracing star formation across cosmic time
• Star cluster formation in the most extreme environments: Insights from the HiPEEC survey
• Formation histories of stars, clusters and globular clusters in the E-MOSAICS simulations
• An EAGLE's View of Ex-situ Galaxy Growth
• The Origin of the Stellar Mass Distribution and Multiplicity
• Where did the globular clusters of the Milky Way form? Insights from the E-MOSAICS simulations
• The [α/Fe]-[Fe/H] relation in the E-MOSAICS simulations: its connection to the birth place of globular clusters and the fraction of globular cluster field stars in the bulge
• The mass fraction of halo stars contributed by the disruption of globular clusters in the E-MOSAICS simulations
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• Spectral properties and detectability of supermassive stars in protoglobular clusters at high redshift
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• A Gemini/GMOS study of the bright elliptical galaxy NGC 3613 and its globular cluster system
• Globular Cluster Systems and X-Ray Atmospheres in Galaxies
• The Predicted Properties of Helium-Enriched Globular Cluster Progenitors at High Redshift