Formation of proto-globular cluster candidates in cosmological simulations of dwarf galaxies at z > 4. Issue 2 (13th April 2023)

• Record Type: Journal Article
• Authors: Sameie, Omid; Boylan-Kolchin, Michael; Hopkins, Philip F; Wetzel, Andrew; Ma, Xiangcheng; Bullock, James S; El-Badry, Kareem; Quataert, Eliot; Samuel, Jenna; Schauer, Anna T P; Weisz, Daniel R
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 522:Issue 2(2023)
• Page Start: 1800
• Page End: 1813
• Publication Date: 2023-04-13
• Subjects: methods: numerical -- galaxies: evolution -- galaxies: formation -- galaxies: high-redshift -- galaxies: star clusters: general; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stad1071
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We perform cosmological hydrodynamical simulations to study the formation of proto-globular cluster candidates in progenitors of present-day dwarf galaxies $(M_{\rm vir} \approx 10^{10}\, {\rm M}_\odot$ at z = 0) as part of the 'Feedback in Realistic Environment' (FIRE) project. Compact ( r 1/2 < 30 pc), relatively massive (0.5 × 10 5 ≲ M ⋆ /M⊙ ≲ 5 × 10 5 ), self-bound stellar clusters form at 11 ≳ z ≳ 5 in progenitors with $M_{\rm vir} \approx 10^9\, \mathrm{M}_{\odot }$ . Cluster formation is triggered when at least $10^7\, \mathrm{M}_{\odot }$ of dense, turbulent gas reaches $\Sigma _{\rm gas} \approx 10^4\, {\rm M}_\odot \, {\rm pc}^{-2}$ as a result of the compressive effects of supernova feedback or from cloud–cloud collisions. The clusters can survive for $2-3\, {\rm Gyr}$ ; 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.