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

J. M. Diederik Kruijssen, Joel L. Pfeffer, Robert A. Crain, Nate Bastian

Research output: Contribution to journalArticlepeer-review

97 Citations (Scopus)


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 realizing 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 characterized 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_*≳ 10^8 M_☉ for redshifts 1 ≤ z ≤ 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....
Original languageEnglish
Pages (from-to)3134-3179
Number of pages46
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - Jul 2019
Externally publishedYes


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