Dynamical Simulations of the First Globular Clusters

Abstract

A Milky Way-like halo is simulated with tidally limited star clusters inserted in the dark matter halos present at high redshift. An n-body code augmented with velocity relaxation in the star clusters evolves the system. The stripped stars and remnant clusters that began in the lower mass sub-halos have a distribution somewhat more extended than the dark matter halo, with a mean galactic radius of about 60 kpc inside 150 kpc, whereas the distribution of all stripped stars and clusters is more centrally concentrated than the dark matter. The clusters from low mass sub-halos, those with a peak circular velocity of 12 − 18 km s −1 , also produce most of the population's thin stellar streams. Together these suggest a search strategy for extremely metal poor cluster stars and their remnants. The dependence of the stellar population distribution on sub-halo mass is not seen in simulations that start clusters at lower redshift. The half mass radii of the clusters are set by the tidal fields of the initial sub-halo, "dwarf galaxy" location, which causes the average half mass radius to decrease with increasing redshift of formation. Starting clusters at greater than redshift 4 leads to cluster half mass radii approximately as seen in the Milky Way.

Hidden in the Haystack: Low-luminosity globular clusters towards the Milky Way bulge

“…From the observational point of view, it seems established that the properties of GCs observed today in the Galaxy are different from those that they had when they formed at ★ Based on observations collected at the European Southern Observatory under ESO programmes 0103.D-0386(A), 105.20MY.001, 179. B-2002, and 198.B-2004. high redshift (Renzini 2017;Carlberg 2020). A similar hypothesis is needed to explain the observations of multiple stellar populations in massive GCs, whereby the first generation of stars must have been much more massive than currently observed, to enrich the second generation (see, e.g.…”

“…Their contribution to the MW assembly has been widely explored in numerical simulations (Kruijssen 2019;Kruijssen et al 2019;Carlberg 2020), presenting the proto-GCs properties and suggesting that most of their stellar content is now lost in the inner Galaxy (Baumgardt et al 2019). From the observational point of view, it seems established that the properties of GCs observed today in the Galaxy are different from those that they had when they formed at ★ Based on observations collected at the European Southern Observatory under ESO programmes 0103.D-0386(A), 105.20MY.001, 179.…”

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

“…Recent progress in modeling the formation of GCs has also been substantial, with a variety of approaches providing frameworks for understanding the formation of GCs both within their host galaxies and in the broader context of galaxy formation theory. Ongoing work on this front includes (1) simulations -at very high resolution but without a full cosmological context -of cluster formation within galaxies or molecular cloud complexes (He et al 2019;Li et al 2019;Lahén et al 2020;Lee et al 2021;Lahén et al 2021;Li et al 2021;Hislop et al 2022); (2) numerical or semi-numerical models of GC formation (which track GCs in cosmological context without directly resolving their formation; e.g., Katz & Ricotti 2014;Ricotti et al 2016;Li et al 2017;Renaud et al 2017;Pfeffer et al 2018;Creasey et al 2019;El-Badry et al 2019;Carlberg 2020;Halbesma et al 2020;Phipps et al 2020;Reina-Campos et al 2022);…”