Formation of proto-globular cluster candidates in cosmological simulations of dwarf galaxies at z > 4

Omid Sameie, Michael Boylan-Kolchin, Philip F. Hopkins, Andrew Wetzel, Xiangcheng Ma, James S. Bullock, Kareem El-Badry, Eliot Quataert, Jenna Samuel, Anna T.P. Schauer, Daniel R. Weisz

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


We perform cosmological hydrodynamical simulations to study the formation of proto-globular cluster candidates in progenitors of present-day dwarf galaxies (Mvir ≈ 1010 M at z = 0) as part of the ‘Feedback in Realistic Environment’ (FIRE) project. Compact (r1/2 < 30 pc), relatively massive (0.5 × 105 ≲ M*/M ≲ 5 × 105), self-bound stellar clusters form at 11 ≳ z ≳ 5 in progenitors with Mvir ≈ 109 M. Cluster formation is triggered when at least 107 M of dense, turbulent gas reaches Σgas ≈ 104 M pc−2 as a result of the compressive effects of supernova feedback or from cloud–cloud collisions. The clusters can survive for 2 − 3 Gyr; absent numerical effects, they could possibly survive substantially longer, perhaps to z = 0. The longest lived clusters are those that form at significant distance – several hundreds of pc – from their host galaxy. We therefore predict that globular clusters forming in progenitors of present-day dwarf galaxies will be offset from any pre-existing stars within their host dark matter haloes as opposed to deeply embedded within a well-defined galaxy. Properties of the nascent clusters are consistent with observations of some of the faintest and most compact high-redshift sources in Hubble Space Telescope lensing fields and are at the edge of what will be detectable as point sources in deep imaging of non-lensed fields with JWST. By contrast, the star clusters’ host galaxies will remain undetectable.

Original languageEnglish (US)
Pages (from-to)1800-1813
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Jun 1 2023

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • galaxies: evolution
  • galaxies: formation
  • galaxies: high-redshift
  • galaxies: star clusters: general
  • methods: numerical


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