Tidally limited star clusters are started on nearly circular orbits in the dark matter sub-halos present at high redshift and evolved with an n-body code augmented with gravitational interactions in the clusters .
The tidally removed stars and the remaining high redshift clusters from a redshift 8 start are more concentrated than the dark matter , as expected .
However , the subset of stars from the 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 .
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 .
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 cluster orbits , which leads to the average half mass radius decreasing with increased redshift of formation .
Starting clusters at greater than redshift 4 leads to cluster half mass radii approximately as seen in the Milky Way , with lower redshifts leading to clusters that are too large .
If extremely metal poor globular clusters were preferentially formed in high redshift , low mass , dwarf galaxies , then the clusters should be spread nearly uniformly over the dark halo , along with their tidally removed stars .